May 2006 (#126):

• The Mailbag, by Kat Tanaka Okopnik
• News Bytes, by Howard Dyckoff
• Preventing DDoS attacks, by Blessen Cherian and Ben Okopnik
• Away Mission -- SDWest 2006, by Howard Dyckoff
• From Assembler to COBOL with the Aid of Open Source, by Edgar Howell
• Plotting time series data with Gnuplot, by Ron Peterson
• Digging More Secure Tunnels with IPsec, by René Pfeiffer
• Column: IT's Enough To Drive You Crazy, by Pete Savage
• HelpDex, by Shane Collinge
• The Linux Launderette

The Mailbag

By Kat Tanaka Okopnik

---

UPDATES from previous HELP WANTED: Article Ideas
Submit comments about articles, or articles themselves (after reading our guidelines) to The Editors of Linux Gazette, and technical answers and tips about Linux to The Answer Gang.

---

• Running Apache and AOLServer Together
• tput cwin question

---

Running Apache and AOLServer Together

[Original question published as LG 122] help wanted #1]

[Evan] -

Modern AOL software for Microsoft Windows uses standard protocols (PPP, PPPoE) to establish link-layer connectivity. It then establishes a TCPIP connection to authenticate the user. This protocol is proprietary. Before authentication, a user's network traffic cannot reach the internet.

To use AOL's ISP service on Linux, one must reverse engineer the authentication protocol. I am not certain anyone has done that.

[Francis] -

Hi there,

If I understand things correctly, the intention is that

client --> s1.example.com:80 --> received by apache --> content generated by apache --> content returned to client by apache

client --> s2.example.com:80 --> received by apache --> apache becomes a client to s3.example.com:8080, which generates and returns content to apache --> content returned to client by apache

I'm assuming above that the client should never know about or connect directly to s3.example.com:8080 -- if that isn't the case, it becomes much easier.

Apache can do this.

In this case, s3.example.com happens to be the same as s2.example.com, but that's unimportant.

In order for it to work, apache needs to know when it should serve something itself, and when it should act as a proxy server for s3. To be a proxy, you'll want mod_proxy and mod_proxy_http. The mod_proxy "ProxyPass" directive, or the mod_rewrite RewriteRule [P] flag will be needed.

Another thing likely to be needed is for the content produced by the origin server to be modified to be sensible from the eventual client's perspective -- things like links, locations (e.g. for redirects), and cookies are the main candidates. The best plan is to make sure the origin server knows how it is being proxied, and to configure it to produce content appropriate for the "real" client, rather than for the apache client it talks to directly.

If that isn't done, you'll need extra features on the apache side to try to catch any place the original details might leak. The "ProxyPassReverse" directive is the first step; it can modify Location, Content-Location, or URI headers from the origin server. You may also need "ProxyPassReverseCookieDomain" and/or "ProxyPassReverseCookiePath" if the cookie-generating part of the origin server wasn't configured as desired. You may also also need something like the third-party mod_proxy_html to rewrite links (src and href attributes) in the returned html, which may also require other modules or libraries to do it right.

Some or fewer of those directives may not be available, depending on the version of apache being used. That appears to be a secret.

Really, if you control the origin server, and will only be accessing it through the front proxy, configure it so that everything it generates is as if it were the world-facing server. With that, none of the content-transforming directives will be needed.

The most general and, I would claim, easiest way to configure this is by name-based virtual hosting.

(I know the OP said virtual hosting wasn't an option in this case, but I'll try to be complete for the rest of the world.)

Logging and directories and the like which are set in the main config are inherited by the virtual hosts, unless overridden there.

The first virtual host is the default one, used when the client-supplied Host: header doesn't match any ServerName or ServerAlias in any VirtualHost sections. Either make it a "please pick a configured site or use a better client" area, or more likely, make it the main one. It's sensible to set ServerName at least

  NameVirtualHost [ip]
  <VirtualHost [ip]>
  ServerName s1.example.com
  </VirtualHost>

  <VirtualHost [ip]>
  ServerName s2.example.com
  # url hierarchy on this server --> remote server
  ProxyPass / http://s3.example.com:8080/
</VirtualHost>

But since VirtualHost'ing is out, we need some other way of determining which urls should be proxied and which should be handled directly.

The next most sensible way is to re-implement the relevant bits of virtual hosting using mod_rewrite, conditional on the Host header sent by the client.

  RewriteEngine on
  RewriteCond %{HTTP_HOST} ^s2\.example\.com$ [NC]
  RewriteRule /(.*) http://s3.example.com:8080/$1 [P]

The other ways I can think of are all quite silly, and involve "RewriteCond %{HTTP_HOST}" or its moral equivalent in a server-side script to correctly handle http://s2.example.com/ anyway, so I won't go in to them.

What else might matter...the content transforming, obviously, if you don't configure the origin server to make it unnecessary. Oh, and all of the clients the origin server sees will be from the apache server's address -- quite possibly localhost, in this setup. So that server may want to play logging or other games to produce pretty output. to produce pretty output.

---

tput cwin question

[Mike's question was originally published in Mailbag LG 123.]

Fri Feb 10 13:13:35 2006
Mike Wright (mike.wright from mail.com)

Hi, I have been trying to figure out exactly what the "cwin" option to the tput command really means.

[Ben] - According to 'man 5 terminfo', it defines a window. According to real-life experience with a variety of xterms, it doesn't do much.

I find that this is generally the case with anything other than a few commands that most xterms have in common. This isn't an area of *nix that has seen much development lately (i.e., the last decade or more) because TclTk and the like have made that kind of text layout, etc., a lot easier _and_ less terminal-dependent than the kind of thing you're trying to do.

What I'm hoping that it will let me do is to create another window in the current terminal using a section of the screen to output listings from different commands that will be executed from numbered menu options. And if the output is several screens then it can be presented a few lines at a time to the user with the option to page down through the many screens of output while not disturbing the menu options at the top of the screen nor the status bars at the bottom of the screen.

I think that you're asking far more of xterms than they can provide. It would be nice if it worked that way, but - as far as I'm aware - it does not.

Why not use several xterms (without decorations) arranged next to each other? I use two tiny xterm windows with a very small font to show my connection status and my mail status in the lower right corner of my screen, something like this:

  xterm -geometry 40x10-0-0 -name ppp -fn 6x9 -e pppd call cell-hs &
  xterm -geometry 40x2-0-100 -name MailTail -e [long command line] &

I also have the above xterm names defined in my ~/.icewm/winoptions file (however, unless you're using "icewm" as I do, these should probably go in your ~/.Xresources file):

  MailTail.dTitleBar: 0
  MailTail.dClose: 0
  MailTail.dMinimize: 0
  MailTail.dMaximize: 0
  MailTail.ignoreTaskBar: 1
  MailTail.ignoreWinList: 1
  MailTail.ignoreQuickSwitch: 1
  ppp.dTitleBar: 0
  ppp.dClose: 0
  ppp.dMinimize: 0
  ppp.dMaximize: 0
  ppp.ignoreTaskBar: 1
  ppp.ignoreWinList: 1
  ppp.ignoreQuickSwitch: 1  

Obviously, you can stack these however you want to. I find that this is a lot more system-independent than trying to play around with terminfo capabilities.

---

GENERAL MAIL

---

• Bind Error
• Webcams
• drvspace under LINUX
• SMS sending S/W

---

Bind Error

Fri Feb 3 03:44:51 PST 2006
Roberto (roberto.bacenetti at lombardiacom.it)

I get an "Address already in use" when trying a bind in the following situation:

a board with an ethernet and a ppp connection:
when the board starts only the ethernet interface is on, and the program successfully binds to the specified port, and is able to accept connections; at some point the partner disconnects and a GPRS PPP connection is established, the old bind is already there and the program can accept a connection, when however the connection is closed any bind will fail, even after a long time has elapsed.

[[[Neil]]] - Reading this again, it sounds as though you are trying to bind to the same port, while the original program is running. If you have bound a socket it will stay bound, even if it has accepted a connection, which has subsequently closed.

I haven't got my reference books handy, but IIRC, you bind() and listen() on one socket, then accept() creates a second socket. The far end disconnecting closes the second socket. If you want to bind to the the original port again, you have to close the first socket also.

i wrote a test program which binds a socket to a specific interface and port:
well with PPP on bind always fails.

[[[Neil]]] - Is PPP relevant here? Do you get the same failure with only the ethernet connection?

Can somone explain this ?

[Neil] - Do answers 2.7and 4.5 in the Unix Socket FAQ answer your question?
http://www.faqs.org/faqs/unix-faq/socket/

[[Roberto]] - It' not a matter of time delay, the error is persistent and I'm using SO_REUSE_ADDR

[[[[Neil]]] - netstat -tulp should tell you which program is already listening on that socket.

thanks

Roberto

---

Webcams

Sun Feb 5 06:16:43 PST 2006
Mike Orr (sluggoster at gmail.com)

What was that program to view webcams on Linux? My friend in the UK (the one mentioned in the iRiver thread) wants to videoconference. He's been bugging me to get a webcam for months but I kept telling him it's such a pain on Linux. Of course he doesn't understand this. "Just plug the camera in and put the CD in the drive, and it installs itself." Yes, on Windows.

I found a webcam HOWTO on linux.com http://www.linux.com/howtos/Webcam-HOWTO/index.shtml and it says some hundred models are supported, but it looks like installing the hardware is only the first part of the problem. Everyone I know who uses webcams transmits them through Yahoo Messenger. There's no like "Internet camera protocol" so you can just attach the camera to a daemon listening on a socket, and view somebody else's camera the same way? The HOWTO mentions camE and Xawtv ('webcam' component), which uploads frames to a website. That's the Linux way to project your webcam to the world? But it seems like it's only good for getting the latest still on a webpage, not for watching a movie. And how do you integrate sound with this?

[Vinayak] - Ayttm has had Webcam support for quite a while now AFAIK. I think the other IM such as everybuddy which use libyahoo2 have webcam support as well.

[Jimmy] - GnomeMeeting (http://www.gnomemeeting.org/) is probably the best known video conferencing app for Linux. There's also a fork of Gaim that has voice and video support (http://gaim-vv.sourceforge.net/).

---

drvspace under LINUX

Thu Feb 9 14:17:15 PST 2006
Jim Doutt (jdoutt-at-whoi-dot-edu)

I am backing up an old DOS disk. It had several 'pseudo' drives (K:, L:) implemented under 'drvspace', which created a file for each drive and treated the contents of the file as a disk.

Using an ISA to USB adapter, I plugged the drive into my Fedora core 3 system and created a image of the whole partition .

  dd if=/def/sda1 of=bkup.img

I then did a loopback mount of that image file 'bkup.img'.

  mount -o loop=/dev/loop3 TI_Travelmate_sda1_windows_20060206.img zz

Great...I can see the DOS files in that image. I also see the files drvspace.000, and drvspace.001 which correspond to my K: and L: drives.

I would like to see the files inside these drvspace files. I have read over dmsdos, but as far as I can tell it was never ported to the 2.6 kernel. I did find a reference to doing a loopback mount using ',cvf_type' mount -o loop=/dev/loop2,cvf_type=dblspace dblspace.001 ../q2 I tried this, and no errors were reported with the mount. However the files and directories had funny names (e.g. ?????.??? etc. ) so the mount was not done properly

Is there a way to do this under LINUX?

[Rick] - I think your only direct access under Linux to those files will be to use the real Microsoft drvspace.bin driver under the "dosemu" emulator. This apparently works well enough, and is detailed here:

http://trillian.randomstuff.org.uk/~stephen/linux/msfilesys.shtml

Over the longer term, you are strongly advised to extract those files from compressed storage, if you care about them. Not only is DriveSpace (and DoubleSpace) pretty unreliable -- and antique -- but also it's just way too darned much trouble to deal with this stuff on an ongoing basis, in my opinion. Good luck!

---

SMS sending S/W

Tue Feb 28 03:57:15 PST 2006
J. Bakshi (j.bakshi at 1net.gr)

Hi list,

there are some sites which can send SMS to mobile. Generally these sites send SMS based on online operation. there are some microsoft based S/W (limited period trial version) too which allow you to compose your messages offline and then send it after connecting with the net; just like SMTP :-) [though I have not tried anything as my box is debian] BUT is there any such Linux based tool allowing offline SMS composing and sending all after getting net connection ??

[Thomas] -

  [n6tadam at workstation ~]$ apt-cache search --names-only sms
  sms-pl - Send SMs via Polish GSM operators
  smsclient - A program for sending short messages (SM / SMS)
  smssend - Utility to send SMS messages to GSM mobile phones
  smstools - SMS Server Tools for GSM modems

[[jbakshi]] - Thanks a lot Thomas.

[Jimmy] - You've been asking questions here for a while, so this won't come as a surprise: you need to provide more information :)

Short answer: yes, there is software for Linux that will allow you to compose and send SMS messages:
http://tuxmobil.org/phones_linux_sms.html

Long answer: In fact, there are three main ways of doing this: via a web interface, mobile phone, and any GSM capable modem. (There are other ways; ICQ for Windows, for example, once had a way of sending SMS via ICQ, but AFAICT that has been discontinued). Heck, you can even run your own SMS (and WAP) gateway on Linux: http://www.kannel.org/ or http://smscgw.ccamp.de/

Web interfaces: I mentioned that you needed to provide more information - which website do you want to use, or, failing that, which network(s) do you want to send to? These programs are basically screen scrapers, and need to be aware of the layout of the site you want to use. smssend http://zekiller.skytech.org/smssend_menu.html), for example, can use several operator's websites, as can the Perl module WWW::SMS (http://search.cpan.org/~eim/WWW-SMS/) - they may not be configured for the network you want to use, however. SMTP2SMS seems
to be configured for Indian providers, so maybe that's what you want? https://sourceforge.net/projects/smtp2sms/

If you want to send messages using your mobile:

• Gnokii: http://www.gnokii.org/ (supports Nokia specific features, though most basic features can be used with any GSM-capable mobile)
• Gammu: http://www.gammu.net/ (Fork of Gnokii, supports some things Gnokii doesn't)
• KMobileTools: http://kmobiletools.berlios.de/
• Gnome Phone Manager: http://usefulinc.com/software/phonemgr/

Using a GSM modem: I can't find the software I used to use, but GSMlib (http://www.pxh.de/fs/gsmlib/) provided the functionality it used.

KXicq2 (http://www.kxicq.org/), an ICQ client for KDE, has support for sending SMS - I'm pretty sure Kopete and Gaim have plugins to do the same. There's even a project that allows a mobile to be mounted as a file system (http://www.gammu.net/projects/snofs.php) that is planning support for sending SMS this way.

HTH

---

2 CENT TIPS

---

• A 2 Cent Tip for Using an Iriver IFP-890 MP3 Player on Linux
• Simple 2-pence tip: Vim :paste / :nopaste
• Comparing all files in a directory

---

A 2 Cent Tip for Using an Iriver IFP-890 MP3 Player on Linux

Sat Feb 4 19:40:47 PST 2006
Chris Gianakopoulos (cgianakop at 1stconnect.com)

Hi Gang,

Here is my latest 2 cent tip for the year (I hope I have more coming).

I've been stuggling on how to get my iRiver mp3 player to interpoerate with my Linux system. The purpose of this posting is to share my results. I have an IFP-800 series player, and it has been updated with firmware so that it appears as a USB storage type of device. Specifically my model is an IFP-890 player.

My Linux distribution is SuSE 8.2, and here are the steps that I performed.

0. Make sure that USB is enabled for hotplug stuff on your system.

1. Update your iRiver mp3 player with their UMS software. The website is here.

You should see a link titled,

iFP-890(cn)_V185ums.zip (1.4 MBytes)

Go ahead and download this file, and reflash the player using the software provided with your mp3 player.

2. As root, create two files to be stored in /etc/hotplug/usb. The two files are called ifpdev and ifp.usermap. The first file will be executed when you plug your mp3 player into your USB port, and the second file describes the required parameters such as vendor id and model. The two files appear below.

  ** Begin ifpdev **************************************


  #!/bin/sh
  # /etc/hotplug/usb/ifpdev
  chgrp usb $DEVICE
  chmod g+rw $DEVICE


  End ifpdev ****************************************

  ** Begin ifp.usermap *********************************


  ifpdev 0x0003 0x4102 0x1108 0x0000 0x0000 0x00 0x00 0x00 0x00 0x00 0x00 0x00000000


  ** End ifp.usermap **********************************

3. As root, add an entry in /etc/fstab. The entry appears below.

  ** Begin fstab entry  *********************************


  /dev/sda             /media/usbDrive      auto       rw,noauto,user,exec 
  
  ** End fstab entry **********************************
   

4. As root, create a directory:

mkdir /media/usbDrive

Now that you've performed all the setup stuff, you just plug your mp3 player into your USB port, and you should hear some beeps indicating recognition of a device being plugged in. Type 'mount /media/usbDrive'.

Now you could access all your music (and whatever else) files :) .

Enjoy!
Chris G.

I forgot to mention in my previous post the source of the script for the hotplug thing. It is http://www.roback.cc/projects/iRiver/.

When I got my mp3 player it didn't have USB filesystem support. I found out about it in a yahoo linux chatroom. Then I beat my head against a wall for about a month after that spending some spare time getting it to interoperate with a linux system. It did pay off. :)

Chris G.

---

Simple 2-pence tip: Vim :paste / :nopaste

Wed Feb 8 13:50:39 PST 2006
Thomas Adam (thomas at edulinux.homeunix.org)

This one is so simple, it's probably always overlooked by many -- or some other alternative solutions are used. There are times (such as viewing a webpage), when one performs "cut-and-paste" from that page, into an editor. I use Vim running in an rxvt. Sometimes (depending on the CR at the ends of the line, there'll be a "stair-case" effect. In the past, I would do (in normal mode):

  ggVG=

to reformat (and reindent) the text, but even that's not always the full solution. The "preferred" way is to do this:

  :set paste

before you paste the text into vim. Then when you're done, issue:

  :set nopaste

... and carry on as normal. It's great. :)

[Kapil] -

I did have this problem (though not with "vim" but "elvis" since that's what I use) and recently found that

:set noai

before the paste and

:set ai

after the paste seems to do the trick. (For non-vi types to get a clue "ai"="autoindent"). "elvis"/"nvi" don't seem to know the "paste" variable/option.

[Ben] -

I just use ":a", then paste and hit 'Esc'. Works for me.

---

2Cent Tip: Comparing all files in a directory

Fri Feb 24 10:26:34 PST 2006
Suramya Tomar (suramya at suramya.com)

Hi Everyone,
Recently I had to compare all files in a directory with all files in another directory to see which of the files had changed and what the differences were.

To run a diff on each file would have taken forever (there were over 300 files in the directory) so I wrote the following script to compare all the files in the current directory with its counterpart in the target directory:

  #!/bin/sh
  # compare_entire_dir.sh
  #    Lets you compare all the files in the current directory with the
  # files in the specified directory.
  #
  # Suramya Tomar (suramya at suramya.com)
  # 23rd Feb 2006
  #
  # Syntax: ./compare_entire_dir.sh target_directory
  ##############################################################################
  
  for file in *;
  do
    echo "Comparing: $file" >> ../compare_results.dat;
    diff -ibw "$file" $1/$file >> ../compare_results.dat ;
  done

It worked surprisingly well for me so I thought I should share it with you all. Hope you find it useful.

Thanks,
Suramya

[Thomas] - I just use 'dirdiff', personally.

[[Peter]] Oooh, nice one, thanks! :)

I wonder if the "unison-gtk" folks ever talked to the "dirdiff" folks...

In unison, it'd be nice to be able to take a quick look-see sometimes, to figure out what actually changed in the files (the way dirdiff shows when you double-click on it).

unison works nicely across ssh, that's why I tend to use it a lot for syncing directory trees (at the time, it seemed easier to pick up and understand than rsync).

[Faber] - I just use 'diff', personally.

[Ben] - I just hit 'Ctl-x d' in Midnight Commander. But Faber's method is definitely more portable.

[[Suramya]] - Umm.. I did use diff to make the actual comparison, the script just loops through each file in the current directory and runs a diff of it against the same file name in the target directory.

[[[Ben]]] - Sure, that was very clear from your script. However, 'diff' is one of those utilities that can take either files _or_ directories as arguments.

Here's an example of how it works:

  ben at Fenrir:~$ mkdir /tmp/foo /tmp/bar
  ben at Fenrir:~$ for n in {a..z}.txt; do cp /etc/hosts /tmp/foo/$n; done
  ben at Fenrir:~$ cp /tmp/foo/{b..y}.txt /tmp/bar

  ben at Fenrir:~$ echo >> /tmp/bar/y.txt 
  ben at Fenrir:~$ echo >> /tmp/foo/b.txt 

So, I've just created a 'foo' and a 'bar' directory in '/tmp', created a list of files in 'foo' (all copies of my '/etc/hosts'), copied the list (except for two files) to 'bar', and slightly modified one file in each directory. Ready? Here we go:

  ben at Fenrir:~$ diff /tmp/foo /tmp/bar
  Only in /tmp/foo: a.txt
  diff /tmp/foo/b.txt /tmp/bar/b.txt
  34d33
  < 
  diff /tmp/foo/y.txt /tmp/bar/y.txt
  33a34
  > 
  Only in /tmp/foo: z.txt
  ben at Fenrir:~$ 

'diff' shows the results of all the differences - both in the list of files and in the files themselves. Pretty good little prog, hey? :)

[[[[Martin]]]] - Didn't know diff could do dirs as well as files... You learn summat new every day... ;)

[[[[Karl-Heinz]]]] - It even has a "-r" flag for recursive diff down the dir-tree (or would that be up as for real trees?)

[[[[Suramya]]]] - ahh.. didn't know that... Thanks for the info.

This also proves the theory that the more you share/teach the more you learn 'cause if I hadn't shared my script I wouldn't have found out that diff supports directories. :)

Thanks,
Suramya

[[[[[Ben]]]]] - I couldn't agree more. I always tell my students to ask lots of questions, even if they seem silly. Discovering the misconceptions they have is just as important as the understanding they're getting from being in class, and perhaps even a bit more than that; once they have the correct perspective, then even their wild guesses are likely to be right.

---

GAZETTE MATTERS

---

• Woomert Foonly

---

Woomert Foonly

Tue Feb 28 2006 10:33:29 -0800
Bradley Chapman (kakadu from gmail.com)

What happened to Mr. Okopnik's Perl guru Woomert Foonly? I was reading back issues of LG and was quite impressed with the stories showcasing the interesting data-munging features offered by Perl, as well as the amusing storylines; are any new stories going to be written?

[Ben] Um... well... good question, Brad. I've been waiting for inspiration to strike, but I seem to be having a long dry spell, inspiration-wise. In fact, I started a story about Woomert and Frink a while back, ran into a major plot snag (what kind of a problem can aliens from another universe have that can be solved with Perl???), and... well, there it's sat, ever since. I've tried writing some other W&F stories a couple of times, but got nowhere.

However, the occasional reminders are useful and stimulating. If another Woomert story comes out in the near future, it'll be your fault. :)

Talkback: Discuss this article with The Answer Gang

---

Kat likes to tell people she's one of the youngest people to have learned to program using punchcards on a mainframe (back in '83); but the truth is that since then, despite many hours in front of various computer screens, she's a computer user rather than a computer programmer. When away from the keyboard, her hands have been found full of knitting needles, various pens, henna, upholsterer's shears, and a pneumatic scaler.

News Bytes

By Howard Dyckoff

Contents: News in General Conferences and Events Distro News Software and Product News Magical Realism....

Please submit your News Bytes items in plain text; other formats may be rejected without reading. [You have been warned!] A one- or two-paragraph summary plus a URL has a much higher chance of being published than an entire press release. Submit items to bytes@linuxgazette.net.

---

Talkback: Discuss this article with The Answer Gang

---

Howard Dyckoff is a long term IT professional with primary experience at Fortune 100 and 200 firms. Before his IT career, he worked for Aviation Week and Space Technology magazine and before that used to edit SkyCom, a newsletter for astronomers and rocketeers. He hails from the Republic of Brooklyn [and Polytechnic Institute] and now, after several trips to Himalayan mountain tops, resides in the SF Bay Area with a large book collection and several pet rocks.

Preventing DDoS attacks

By Blessen Cherian and Ben Okopnik

Note from the Editor

	C is as sphere as Earth. It's center is everywhere and circumference is
	nowhere and hence what you see in daylight is only one percent of what you
	can see in darkness.
	 -- cited from an article submitted to LG (anonymous)

With the agreement of the original author of this article, I've listed myself as co-author here, since I essentially rewrote the article that was submitted. Normally, proofing an article and adding some HTML structure is just part of the job here at LG; however, complete reformatting of idiom, recasting of nearly every paragraph, and updating the technical information is well beyond the scope of what is normal.

I hate to reject an article that has excellent technical merit almost as much as I want to avoid publishing one that would be unintelligible to many of our readers (particularly those for whom English is not their primary language, or who have difficulty parsing it for other reasons.) However, I also feel that doing what is essentially a major rewrite of an article should not go unrecognized. Since this is the first time I've ever explicitly taken credit for doing this kind of major reconstruction - and since my own vewpoint here could be tainted by the fact that it's my work that's involved - I want to solicit comments, ideas, and suggestions from you, our readers. Anyone want to volunteer as a stand-by co-author? Got an alien idiom-conversion ray that's been in your attic for the last hundred years? Do you see some other obvious solution I've missed? Bring'em on; the 'Talkback' link at the end of this article is your friend.
-- Ben Okopnik, Editor-in-Chief

---

Introduction

In this article, I will try to explain what DDoS is, and how it can be prevented or mitigated. Many of the servers in datacenters these days are Linux-based; hence, I'm going to discuss DDoS attack prevention and mitigation for Linux servers.

DDoS happens due to lack of security awareness, application, or skill on the part of the network/server owners or adminstrators. We often hear that a particular machine is under DDoS attack, or that the NOC has unplugged a given machine due to its participation in a DDoS attack. DDoS has become one of the common issues in our world. In some ways, DDoS is like a disease which doesn't have a countering antibiotic, and requires being very careful while dealing with it. Never take it lightly. In this article, I'll try to cover the steps/measures which will help us defend our machines from a DDoS attack - at least up to a certain extent.

What Is A DDoS Attack?

Simply stated, DDoS (Distributed Denial of Service) is an advanced version of the DoS (Denial of Service) attack. Much like DoS, DDoS also tries to block important services running on a server by flooding the destination server with packets. The specialty of DDoS is that the attacks do not come from a single network or host but from a number of different hosts or networks which have been previously compromised.

DDoS, like many other attack schemes, can be considered to consist of three participants; we can refer to these as the Master, the Slave, and the Victim. The Master is the initial source of the attack - i.e., the person/machine behind all this (sounds COOL, right?) The Slave is the host or network which was previously compromised by the Master, and the Victim is the target site/server under attack. The Master informs the Slave(s) to launch an attack on the victim's site/machine; since the attack comes from multiple sources at once (note that the Master is usually not involved in this phase), it is called a Distributed (or co-ordinated) attack.

How Do They Do It?

DDoS occurs in two phases. In the first phase, the owner of the Master host compromises vulnerable machines in different networks around the world and installs DDoS tools (i.e., programs that will perform the attack once they're triggered.) This is called the Intrusion phase. In the next phase, the Master sends out the triggering information to those compromised hosts, which usually includes the IP to be attacked (conversely, that IP could have been pre-programmed into the tools, and the attack could be time-triggered - e.g., the Code Red virus DDoS against the http://whitehouse.gov servers.) This is called the Attack phase.

What Allows Them To Do It?

The success of the Intrusion phase relies on the presence of vulnerable machines on an arbitrary network. Unfortunately, there's a very large number of naive computer owners and system administrators whose machines are largely unprotected, and thus this phase will be easily accomplished by the attacker in almost all cases.

Some of the factors that make the Slaves-to-be vulnerable are:

1. Vulnerable software/applications running on a machine or network.
2. Open/unprotected network configuration.
3. Hosts configured without taking security into account.
4. Absence of monitoring or data analysis.
5. No regular audit or software upgrades being conducted.

What Should We Do If We Are Under Attack?

If your host is one of the Slaves in a DDoS, you will most likely never even be aware of it - unless you carefully examine your logs and watch for untoward network activity. If, on the other hand, you're the Victim, the results will be dramatic and obvious.

Symptoms (Victim):

1. Programs run very slowly
2. Services (e.g., HTTP) fail at a high rate
3. Large number of connection requests from different networks
4. User complaints about slow (or no) site access
5. Machine shows a high CPU load

If you discover that you're under attack, follow these steps:

• Check if your CPU load is high and you a have large number of HTTP process running
  Check the load using the 'w' or the 'uptime' commands:

  Blessen@work >w
   12:00:36 up 1 day, 20:27, 5 users, load average: 0.70, 0.70, 0.57 
  

  Count the number of HTTP processes (it helps to know what your normal count is for comparison):

  [root@blessen root]# ps -aux|grep -i HTTP|wc -l 
  23 
  

• Determine the attacking network
  In a heavily-loaded server, the number of connection may be above 100 - but during a DDoS attack, the number will go even higher. That's when we need to find out, as quickly as possible, which networks are launching these attacks. In a DDoS attack, the individual slave machine doesn't have much importance; it is the network which matters the most, since an attacker could be using any or even all of the machines on a compromised network. Consequently, the network address is of crucial importance.

  Executing the following command will show the IPs arranged in order of established connections:

  bash# netstat -lpn|grep :80|awk '{print $5}'|sort
  

  For an average host, if you have more than 30 connections from a single IP, chances are that you're under attack. In normal operation, there is very rarely any reason for that many connection requests from a single IP. Identify these networks for later reporting, perhaps by using the 'whois' command.

  If more than 5 such hosts/IPs connect from the same network, that's a very clear sign of DDoS.

• Block the attacking network
  This can be done by using 'iptables' or 'apf':

  iptables -A INPUT -s <Source IP> -j DROP 
  

  If you're running 'apf', simply add these IPs to the '/etc/apf/deny_hosts.rules' file. Continue this elimination process until the attack on the machine is reduced (and hopefully, eventually stopped altogether.) As a follow-up measure, contact the datacenter/NOC responsible for that network to inform them of the compromised systems.

  As a longer-term strategy, once the immediate attack is over (or, if you're smart, you can do it right now :), install Portsentry (see the software listed at the end of this article.)

How can we prevent or defend ourselves from these attacks?

There is no complete or perfect solution to DDoS. The logic is simple: NO software or countermeasures can stand up to attacks from, say, 100 servers at once. All that can be done is to take preventive measures, and respond quickly and effectively when the attack takes place.

As it is often said, an ounce of prevention is better than a pound of cure - and this is very true in the case of DDoS. In the introduction, I had mentioned that DDoS often happens because of vulnerable software/applications running on a machine in a particular network. Attackers use those security holes to compromise the hosts and the servers and install the DDoS tools such as 'trin00'.

To prevent or mitigate future DDoS attacks, follow these steps:

• Create and implement a good security policy
• Set up a firewall which does ingress and egress filtering at the gateway (e.g., APF from http://www.rfxnetworks.com/apf.php)
• Use host-based intrusion detection on your gateway/hosts to alert you to port scans and break-in attempts (e.g., AIDE from http://freshmeat.net/projects/aide/)

To prevent your network from being used as a slave, follow these steps:

• Conduct regular audits on each host on the network to find installed DDoS tools and vulnerable applications.
• Use tools like Rkdet, Rootkit Hunter, or chkrootkit to find if a rootkit has been installed on your system.
• Perform a general security audit on your systems on a regular basis:
  • Keep your systems up to date to minimize software vulnerabilities (kernel and software upgrades)
  • Check for rootkits
  • Check logs for evidence of port sniffing, etc.
  • Check for hidden processes by comparing the output of 'ps' and 'lsof'.
  • Use auditing tools (i.e., Nessus, SAINT, or SARA)
  • Check system binaries with, e.g., Tripwire to see if they've been changed since your last snapshot
  • Check for open email relays
  • Check for malicious cron entries
  • Check /dev /tmp /var directories for odd files (i.e., '...', wrong permissions/ownership on device files, etc.)
  • Check whether backups are maintained
  • Check for unwanted users and groups (examine /etc/passwd)
  • Check for and disable any unneeded services
  • Check for SUID, SGID, and 'nouser' files on your system with the 'find' command
  • Check the system performance (memory and CPU usage); note the average levels
• Create a DSE (Dedicated Security Expert) team for your company.
• Enforce and implement security measures on all hosts in the network. The only hosts that should be allowed on your network are ones that have been vetted by your security admin or DSE (Dedicated Security Expert). All hosts on the network should be checked on a regular basis by your DSE team.
• Collect your network and host data and analyze them to see what kind of attacks are being run against your networks.
• Implement Sysctl-based protection. Enable the following in your '/etc/sysctl.conf':

  # Enable IP spoofing protection, turn on Source Address Verification 
  net.ipv4.conf.all.rp_filter = 1 
  
  # Enable TCP SYN Cookie Protection 
  net.ipv4.tcp_syncookies = 1 
  

  Conversely, you could add this code to your '/etc/rc.local':

  for f in /proc/sys/net/ipv4/{conf/*/rp_filter,tcp_syncookies}
  do
  	echo 1 > $f
  done 
  

• Install PortSentry to block scanning hosts.
• Add 'Mod_dosevasive' to your Apache installation. This is an Apache module which performs 'evasive' action in the event of an HTTP DDoS attack or brute force attack.
• Install the 'Mod_security' module. Since DDoS often targets HTTP (port 80), it's a good idea to have a filtering system for Apache; 'Mod_security' will analyze requests before passing them to the web server.
• Set up load balancing for your services. In some ways, this is the most powerful network-based defense against DDoS.
• Create awareness of security issues.

Conclusion

DDoS attacks can be mitigated at the target machine and prevented at the slave network by implementing proper security. My advice to each and every server and network owner is to implement effective security measures; since DDoS is a network-wide problem, preventing it is going to require everyone's help.

Talkback: Discuss this article with The Answer Gang

---

My name is Blessen and I prefer people calling me Bless. I got interested in Linux when I joined the software firm, Poornam Info Vision Pvt Ltd also known as Bobcares. They gave me exposure to linux.

I am a B.Tech in Computer Science from the College of Engineering, Chengannur. I passed out in the year 2001 and got into the company that year. During my work, I was passionate with Linux security and I look forward to grow in that field.

My hobbies are browsing net, learning new technologies and helping others. In my free time I also develop open source softwares and one of them is a scaled down version of formmail. The project is called "Smart Mail" which is more secure than formmail.

---

Ben is the Editor-in-Chief for Linux Gazette and a member of The Answer Gang.

Ben was born in Moscow, Russia in 1962. He became interested in electricity at the tender age of six, promptly demonstrated it by sticking a fork into a socket and starting a fire, and has been falling down technological mineshafts ever since. He has been working with computers since the Elder Days, when they had to be built by soldering parts onto printed circuit boards and programs had to fit into 4k of memory. He would gladly pay good money to any psychologist who can cure him of the recurrent nightmares.

His subsequent experiences include creating software in nearly a dozen languages, network and database maintenance during the approach of a hurricane, and writing articles for publications ranging from sailing magazines to technological journals. After a seven-year Atlantic/Caribbean cruise under sail and passages up and down the East coast of the US, he is currently anchored in St. Augustine, Florida. He works as a technical instructor for Sun Microsystems and a private Open Source consultant/Web developer. His current set of hobbies includes flying, yoga, martial arts, motorcycles, writing, and Roman history; his Palm Pilot is crammed full of alarms, many of which contain exclamation points.

He has been working with Linux since 1997, and credits it with his complete loss of interest in waging nuclear warfare on parts of the Pacific Northwest.

Away Mission -- SDWest 2006

By Howard Dyckoff

This March conference, at the Santa Clara Convention Center, has been the flagship conference of the CMP empire. This year SDWest offered the usual solid matrix of developer tracks, but showed a growing emphasis on security in software development. There were also a significant number of sessions focusing on Agility in the development process, meaning that Agile methods are becoming mainstream.

Not only did we have Scott Ambler [an industry-recognized software process improvement (SPI) expert and contributing editor with Dr. Dobb's Journal] discussing XP, RUP, and SCRUM in an evening BOF and Agile Modeling in a halfday tutorial, but he also presented a technical session on Agile UP - Streamlining the Rational Unified Process (RUP). In fact, there were 47 sessions referencing "Agile" methods out of 235 total sessions including titles such as "Agile Estimating and Planning", and "User Stories for Agile Requirements".

Another trend was the rise of AJAX. Almost as many sessions addressed this REST approach to updating web pages as sessions focused on Web Services [including WS-Security]. This is the paradigm du jour for new web development.

One of the surprises at the conference was seeing the last run by the now-defunct Software Development magazine. The whole operation -- articles, archives, conferences, etc -- are now under the Dr Dobbs logo. So future conferences will be "Dr. Dobbs' SD Expo" conferences, and the URL "http://www.sdexpo.com" is redirected to the Dr. Dobbs site. Although this is partly a rebranding effort, some of the well-known staff personalities were not visible. I would speculate that some other publications in the CMP stable may also do the consolidation dance this year. [as a note of historical interest, "Software Development" used to be called "Computer Language"]

This year, Microsoft's Visual Studio swept the awards. The VS product manager, Rick LaPlante, went up a record 4 times for the Jolt awards. This included Jolt's Best Product Award along with several others, including the prestigious long-term Accomplishment Award. They also had one of the last keynotes to present the new features of the award-winning VS Team System product.

The VSTS demo showed integrated unit test refactoring, code coverage checking, and result tracking. Everything goes into a data warehouse for team access, and reports are available in Word and Excel formats. Also, VSTS has wizards for building stress and performance tests which show bottlenecks via automatic instrumentation. The final part of the demo showed linking TEAMprise in a Linux environment to the VSTS repository -- impressive, and maybe something that would catch your boss's eye, but the TEAMprise folks started as developers of VS addins. TEAMprise is not primarily a Linux vendor.

For balance, Rails 1.0 won the Jolt award for Web Development Tools.

See the full listing of SDWest award winners here: http://www.ddj.com/pubs/sdmag/jolts/

Mechanical Turk

The best keynote also had the most intriguing title -- Artificial Artificial-Intelligence and the Web. This was partly an introduction to Amazon's experiment with with making public Web Services [and flexing its software muscles], introduced by Amazon's WS evangelists Philipe Babrera and Jeff Barr.

To tease our interest, the presenters retold the arcane history of the 19th Century enigma, the Mechanical Turk. This was purported to be a mechanical chess player seated at a chess board that could play winning games. In actuality, a very small chess master controlled the mechanism from the trunk beneath the board that supposedly housed the machinery. Because a human was in the mix, this was a form of "Artificial Artificial-Intelligence" and Amazon has borrowed the name for its new Web Service that links computers and humans.

The big idea is to use human interaction to understand input questions and their context, aided by web automation.

Clients can ask for services at http://mturk.amazon.com [which is really an asynch parallel network of human processors].

The task are farmed out to HITs -- Human Intelligence Tasks. The Web Service organizes the tasks, allows human agents to volunteer for the tasks, collects and forwards the results to the requesters. And all of this is organized by micropayments of a penny or a dime or even a dollar a HIT.

On a practical level, Amazon had millions of photos of business addresses, many similar and some just mislabeled. So they used the Mturk community to verify and clean out inventory. They made small payments for each verifed or corrected image and spent only a fraction of what the effort would have cost by an outside agency. In effect they harnessed the intelligence and knowledge of a large community of web users. Of course, some members of the audience were concerned that this might create a legion of web wage serfs, working at or below legal minimum wage.

A new company has organized itself around this service, http://askforcents.com. Currently they are offering free requests as they workout the service details and business model.

AJAX and REST

Christian Gross, Chair of SD Web Services Track, gave a back-to-back double session on "Developing With AJAX and REST Patterns" to a full house. [ AJAX represents the next generation of dynamic web development, Gross said. ]

REST is a development technique for Web Services using HTTP and, very often, XML. REST has ruffled feathers in the Web Services world because of its 'simpler is better' development strategy. For example, Ajax-Rest Components are agnostic and do not require a file ending like .html, .aspx, or .jsp.

Besides examples of mash-ups and instantly updating sections of web pages, Gross compared AJAX to technologies such as SOAP, and CORBA/DCOM/IIOP. Examples and a short overview are available from: http://www.devspace.com:8088/. Also see Christian's blog at devspace: http://www.devspace.com/index.php?paged=2.

For his Ajax Patterns Framework, try this link: http://www.devspace.com/~cgross/sources/snapshot/ajaxframework.zip.

And for a really detailed overview on AJAX, visit: http://www.telerik.com/default.aspx?pageid=2692.

Another gem of SDWest06 was the 2-day tutorial from C++ Experts Bjarne Stroustrup and Herb Sutter. This required a special VIP or C++ Tutorial Pass for attendance. It began with a 25th-anniversary keynote placing C++ in historical and future context. Among other topics were new ISO C++ Libraries, C++(0x) and the Concur Project, and Exception Safety. A full description is available here: http://www.sdexpo.com/2006/west/tutorial.htm.

An added "Grab Bag" technical track included sessions such as "Essential Virtual Computing Tips and Tricks" for VMWare and Virtual Server and "Open Source ROI" which offered real world case studies. [Here is a link to the Open Source Maturity Model that was discussed: http://www.navicasoft.com/pages/osmm.htm ]

The Roundup....

Costs --- over $2000 for a full conference and tutorial pass, although organizations can avail themselves of the "fourth person attends FREE" discount for a net 25% savings. In comparison, pricing for EclipseCon and the MySQL User Conference is under $1500. Of course, this is still less than the $2,495.00 Early Bird discount for conference and tutorials at JavaOne.

The Expo was small again, but featured a good mix of build tools, code testers and software houses. There were raffles for Sirius satellite radios, American Express checks, free software, and trainings. But by far the most interesting was Macabe's instant lottery. They offered a check for $100,000 [!!!] if some one punched in the correct 6 numbers on a key pad. That would be easy if you had 999,999 chances, or knew the previous entries, but no one did.

This year again SDWest conferencees got large black tote bags and again had sandwiches each day in boxed lunches. On these points, EclipseCon was clearly superior with a logoed backpack and full sitdown meals. Of course, EclipseCon was much more narrowly defined - but that is also an advantage; it was all Eclipse, all the time.

The best reason to come to the next SD Conference is the stellar cast of developers and trainers who run the rich and detailed technical sessions. And the broad scope and platform agnosticism is also refreshing. You can't eat those things in many other conferences...

Talkback: Discuss this article with The Answer Gang

---

Howard Dyckoff is a long term IT professional with primary experience at Fortune 100 and 200 firms. Before his IT career, he worked for Aviation Week and Space Technology magazine and before that used to edit SkyCom, a newsletter for astronomers and rocketeers. He hails from the Republic of Brooklyn [and Polytechnic Institute] and now, after several trips to Himalayan mountain tops, resides in the SF Bay Area with a large book collection and several pet rocks.

From Assembler to COBOL with the Aid of Open Source

By Edgar Howell

Introduction

Recently I had occasion to help convert an Assembler program into COBOL. The Assembler part of it was familiar to me from the old days of IBM Assembler 360/370/390, which was source-compatible with that used by Siemens, Amdahl, and others at one time or another on so-called "big-iron". For other than systems work, Assembler is gradually falling out of favor, not without justification, based on some of what I have seen over the last decade or so. Within this environment, COBOL is still a reasonable and viable alternative.

The Problem

The program in question was well over 6000 lines of code -- 8000 with macro expansions -- and easily would have taken several weeks to convert completely by hand. Only then could compilation and testing start. A nightmare.

Fortunately, for many years one of the participants in the project has been working on tools to improve the quality of Assembler code as well as to convert it to PL/1 or COBOL. But it is in the nature of Assembler that such a tool can never be finished. Many of the Assembler programs I've seen in the past remind me of a demolition derby: getting there is all that counts, it doesn't matter how you do it!

I was given a copy of the Assembler program in which each line had a unique line number, as well as a copy of the COBOL program produced by software which had references to the line number of Assembler code that caused generation of that particular line of COBOL code. And "all" I had to do was review the generated code and adapt it as needed. Hmmmm...

Manual Work

Had it only been necessary to make minor changes here and there, likely the task would have been quickly finished. But there were numerous places where something needed to be adjusted, often the same problem, just a variation on a theme, and another place where another change meant another chance of making a mistake.

To be sure, the vast majority of the software-generated code was in excellent condition - but this isn't horseshoes. Even though the customer will have to make final adjustments based on his operating environment, it just wouldn't do to turn the final product over with too many problems.

As it turned out, the biggest problem was that the software faithfully produced COBOL code that replicated the Assembler code very closely. Where the original code was clean, so was the COBOL.

Assembler vs COBOL

Here is a small example of the problem. The following Assembler code, which defines storage to manipulate the date (century, year, month day) -

    H1CYMD   DS    0CL8
    H1CYM    DS    0CL6
    H1CYY    DS    0CL4
    H1C      DS    CL2
    H1YY     DS    CL2
    H1MM     DS    CL2
    H1DD     DS    CL2

resulted in the following COBOL:

    01  H1CYMD PIC X(8). 
    01  filler6607 REDEFINES H1CYMD. 
            10 H1CYM PIC X(6). 
            10 filler6608 REDEFINES H1CYM. 
                    20 H1CYY PIC X(4). 
                20 filler6609 REDEFINES H1CYY. 
                            30 H1C PIC X(2). 
                            30 H1YY PIC X(2). 
                            30 filler6611-0 REDEFINES H1YY. 
                                35 H1YY-char PIC X(6). 
                            30 filler6611 REDEFINES H1YY. 
                                35 H1YY-2-char PIC X(4). 
                20 H1MM PIC X(2). 
            10 H1DD PIC X(2). 

Aside from the fact that this COBOL is pig-ugly, it isn't even syntactically correct!

However, this is not due to the software but the Assembler code itself: in the symbol table H1YY has a length of 2 because of its explicit declaration with that length, but the REDEFINES H1YY-char has a syntactically invalid length of 6 because that is the explicit length used with it at one point in the Assembler program. That's not syntactically incorrect in Assembler, but it is up to the programmer to know whether that length is reasonable to use. Originally, it was - but not in COBOL.

But there is no way I could have a chance of finding every situation like that by hand. Now what?!

Open Source to the Rescue

The Norns have been very kind to me of late. A while back I had discovered a COBOL complier for Linux but hadn't had the time to investigate it. The problem with it was that since it wasn't part of any distribution I had, I couldn't just grab an RPM and plop it onto one of the machines and expect it to function.

It was now time to make time.

Installing Open COBOL under SuSE 10.0

As usual, nothing ever goes smoothly the first time - and installing this package was no exception. In the following, I have omitted the false starts, other than to demonstrate what to do if that should happen to you. Basically, by not doing my homework up front, I gained a certain level of experience at that. Do pay attention to prerequisites when a package you are interested in is kind enough to let you know in advance.

The documentation that came with Open COBOL listed the following packages as required:

   libgmp      decimal arithmetic
   libtool     dynamic CALL statements

The following were optional:

   libdb       indexed file I/O and SORT/MERGE
   libncurses  SCREEN SECTION

Using YaST, I installed four of the following packages (listed as required for development) that were available but not yet installed:

   autoconf
   automake
   libtool     present
   gettext     present
   bison
   flex

Installation then went as follows (indentation indicates a different GUI window and CTRL-D exits root status):

mkdir /tmp/COBOL
cp /media/usb01/COB/open-cobol-0.32.tar.gz /tmp/COBOL/
cd /tmp/COBOL
tar xzf open-cobol-0.32.tar.gz
cd open-cobol-0.32
./configure

This failed because one of the required packages had not yet been installed. No biggie, I just opened another window and installed GMP.

      mkdir /tmp/GMP
      cp /media/usb01/COB/gmp-4.1.4.tar.gz /tmp/GMP/
      cd /tmp/GMP
      tar xzf gmp-4.1.4.tar.gz
      cd gmp-4.1.4
      ./configure

This also failed since I hadn't anticipated doing any "development" in this partition. So I fired up YaST and installed gcc as well as glib2-devel and glib2-doc (instead of glib-* since glib2 was already installed).

      ./configure
      make  

This took a tremendous amount of time to write endless messages to the screen. Well, that is what you will think if you have never run 'make' before.

      su
      make install

At this point you will need to note for later (export) the messages regarding /usr/local/lib or whatever.

      make clean
      CTRL-D  <end root status>
./configure

The following messages at the end are merely informative ("no" due to absence of optional packages):

            Use gettext for international messages: yes
            Use Berkeley DB for file I/O:           no
            Use fcntl for file locking:             yes
            Use ncurses for screen I/O:             no

make
su
make install
make clean
CTRL-D  <end root status>

Initial Tests

The only thing left to do was to see if it had been worth all the effort.

cd <directory_with_test_programs>
export LD_LIBRARY_PATH=/usr/local/lib
cobc hello.cob
./hello
Hello World!

After that I spent a bit of time playing around with what the compiler can handle. Here you can see a bit of code using decimal arithmetic -- which blew me away! But, then, that is what the GMP package is all about.

That worked so well that I decided to dig out an almost 20-year-old test program from a COBOL package that worked under MS-DOS. Minimal compiler error messages. And after I made comments of a couple of lines of code, the program compiled. And executed! Like access to the date and time in the machine, output to the screen, input from the keyboard. And I didn't have to change anything!

The Acid Test

OK, so it's time to see if this thing can help me with my real-world problem. I fed it the program I had been working on and among the error messages were:

/tmp/temp.cob:2081: size of 'filler6611-0' larger than size of 'H1YY'
/tmp/temp.cob:2083: size of 'filler6611' larger than size of 'H1YY'

I'm a believer!

Conclusion

While I may never have need to do any program development with this COBOL compiler, in a very brief period of time it has made a big impression on me. It seems to produce good code, although divide by zero didn't give the response I expected. Still, the ability to deal with decimal arithmetic is very impressive.

It seems to be very good at discovering syntactic errors in source code. I spent considerable time finding and fixing minor syntax problems that I never ever would have found just by reading the code. Exactly what I had hoped for.

And it ought to be perfect for anyone wanting to learn COBOL at home without the time pressure or expense of a formal class somewhere.

Due to dependencies, installing Open Source programs can turn into a bit of a pain, particularly if the discrepancies between your system and the requirements of the package are too great. But within reason this can be overcome, as you saw above. And in all likelihood, the accompanying documentation will let you know what is needed.

It can certainly be worth your taking the time to try out that package of interest.

Talkback: Discuss this article with The Answer Gang

---

Edgar is a consultant in the Cologne/Bonn area in Germany. His day job involves helping a customer with payroll, maintaining ancient IBM Assembler programs, some occasional COBOL, and otherwise using QMF, PL/1 and DB/2 under MVS.

(Note: mail that does not contain "linuxgazette" in the subject will be rejected.)

Plotting time series data with Gnuplot

By Ron Peterson

Introduction

Good systems administrators log stuff. Lots of stuff. A lot of the information we collect consists of time series data: a set of numerical values assocated with a sequence of discrete time values.

There are any number of tools to help the diligent sysadmin monitor this data visually as it is collected. A good many of them are built using Tobias Oetiker's excellent RRDTool. Some noteworthy examples include Cacti, Cricket, and Smokeping. There are many others.

That's all well and good as long as you know what you want to monitor. However, sometimes you'd just like to do some quick ad hoc visualization. As you might surmise, most Linux systems provide a myriad of visualization tools (Grace and GRI come to mind). In this article, I'll introduce you to Gnuplot, focusing specifically on how to plot time series data.

Prepare some data

Gnuplot without data is like gravy without potatoes. So before we get to the gravy, let's make some potatoes. Let's say for the sake of argument, or at least for the purpose of giving the rest of the article something to talk about, I include the following line in my system's crontab file:

*/1 * * * * root /bin/cat /proc/loadavg 2>&1 | /usr/bin/logger -p local3.info -t CRON-LOADAVG

If you're like me, and have configured your system's syslog.conf as follows:

local3.*  /var/log/cron.log

...then you will find all local3 facility messages in their own special file. Because we're telling 'logger' to tag all of our load average data, it will be easy to extract this information from the rest of our logfile clutter. A simple 'grep CRON-LOADAVG /var/log/cron.log > load.dat.1' should do nicely. This will give us a file that looks like so:

Mar 19 00:30:02 ahost CRON-LOADAVG: 0.40 0.78 1.19 11/296 3690
Mar 19 00:31:01 ahost CRON-LOADAVG: 3.54 1.55 1.41 4/311 3997
Mar 19 00:32:01 ahost CRON-LOADAVG: 2.68 1.59 1.43 2/278 4142
...

Now let's extract just the data we want:

cat load.dat.1 | tr -s ' ' ' ' | cut -d' ' -f1,2,3,6 > load.dat.2

The translate command 'tr' squishes multiple spaces into a single space, so that we can expect more consistent behaviour from the 'cut' command. In this case, the translate command 'tr' is superfluous, but I think it's a good habit nonetheless. With any luck, our data now looks something like:

Mar 19 00:30:02 0.40
Mar 19 00:31:01 3.54
Mar 19 00:32:01 2.68
...

That's almost perfect. Unfortunately, our gnuplot example will expect two space delimited columns of input, so we need to replace the spaces delimiting our timestamp components with some other character, like a hyphen.

perl -pe 's/(.*?)\s(.*?)\s(.*)/$1-$2-$3/;' load.dat.2 > load.dat.3

This isn't a Perl article, so I won't bore you with the details of what this command is doing. In the interest of pedagogy though, I think it's helpful to illustrate how sausages are sometimes made; even if it does make me look like a butcher. Our data now looks like:

Mar-19-00:30:02 0.40
Mar-19-00:31:01 3.54
Mar-19-00:32:01 2.68
...

Plot it

Now it's time for the gravy. First I'll give you a taste, and then I'll explain the recipe. Create a file with the following contents, excluding the line numbers. Call it 'plot-load.conf'. Edit the date range on line six to include the extents of your data.

1  set terminal png size 1200,800
2  set xdata time
3  set timefmt "%b-%d-%H:%M:%S"
4  set output "load.png"
5  # time range must be in same format as data file
6  set xrange ["Mar-25-00:00:00":"Mar-26-00:00:00"]
7  set yrange [0:50]
8  set grid
9  set xlabel "Date\\nTime"
10 set ylabel "Load"
11 set title "Load Averages"
12 set key left box
13 plot "load.dat.3" using 1:2 index 0 title "ahost" with lines

If you run the following command, you should end up with a file called 'load.png'. Use your favorite image viewer to take a look. Hopefully nothing too alarming shows up.

cat plot-load.conf | gnuplot

The first line of our gnuplot command file says to create a PNG file, and gives its dimensions. PNG is only one of a myriad possible output formats. The second line says our X axis represents time data. The third line uses standard date format specification (see 'man date') to indicate what our data file's timestamp data looks like. We must use the same format in line six, where we indicate our graph's start time and end time. You can omit this, but I find it's useful to anchor the endpoints, particularly when plotting multiple data sources in a single graph. Line seven sets the plot limits of our Y axis.

Line 13 deserves a little bit of extra attention. The name of our data source comes first. The 'using 1:2' bit means to extract data from columns one and two of our data source. The 'index 0' bit means to use the first data set in the file. Data sets are delimited by pairs of blank records. Our file was simple. It only comprised col1 and col2 of data set zero in the following pseudo data file.

# data set zero
col1 col2 col3 col4
col1 col2 col3 col4
col1 col2 col3 col4


# data set one
col1 col2 col3 col4
col1 col2 col3 col4
col1 col2 col3 col4
col1 col2 col3 col4


# data set two
col1 col2 col3 col4
col1 col2 col3 col4
col1 col2 col3 col4

Asuuming we had multiple data sets in a single file (perhaps we want to compare load averages from multiple hosts), one way we could combine this data into a single graph would be to expand our line 13 as follows:

plot "load.dat.3" using 1:2 index 0 title "ahost" with lines, \
plot "load.dat.3" using 1:2 index 1 title "bhost" with lines, \
plot "load.dat.3" using 1:2 index 2 title "chost" with lines

Conclusion

Potatoes are nice, but as Trotsky once noted, they are "the classic symbol of poverty". Knowing how to quickly whip up some time series plots is useful, but Gnuplot is capable of far more than I've even hinted at in this article. Hopefully I've managed to whet your appetite to learn even more.

Best.

Talkback: Discuss this article with The Answer Gang

---

Ron Peterson is a Network & Systems Manager at Mount Holyoke College in the happy hills of western Massachusetts. He enjoys lecturing his three small children about the maleficent influence of proprietary media codecs while they watch Homestar Runner cartoons together.

Digging More Secure Tunnels with IPsec

By René Pfeiffer

Introduction

In my last article about IPsec we learned about the building blocks of IPsec in the Linux kernel. We took a look at the tools needed to build encrypted and secured data paths between two hosts. Now we'll use this knowledge and move a step further on.

IPsec is often used to connect two or more different networks by using tunnels. If you have a complex setup, then exchanging keys manually and keeping track of them can get very challenging. IPsec offers a way of handling keys automatically. Let's take a look how this works.

Entering the Tunnels

We already know how to encrypt all data between two hosts. We created the keys and put them into the setkey.conf file, where we also configured our security policy that tells the kernel to use IPsec between the IP addresses of our hosts. When using IPsec for remote access purposes, it is far more useful to reach a whole network of hosts than only one IP address. You can do this by using IPsec's tunnel mode. Let's assume that we have two networks named A and B. Both are "behind" two gateways named after the nearest connected network. The classical way to connect both networks is to install a route on both gateways. This means that every packet between network A and B travels unencrypted through the direct connection.

We want to use IPsec instead. This means that both gateways still need to see each other, and we still have the direct connection. In addition to that, we get a "second" way our packets can travel. We call this connection a virtual connection or tunnel. Only the tunnel holds our packets travelling between network A and B. They are encapsulated into ESP or AH packets. The direct connection holds the corresponding IPsec packets (i.e. the AH and ESP packets itself). You have to keep this in mind when creating configurations. Compared to the two single host scenario we have more addresses involved. We need the gateway and the network we want to connect to. If you know this information, then you can begin to create an appropriate entry for the gateways' Security Policy Databases (SPD).

#!/usr/sbin/setkey -f
#
# SPD for gateway A (172.16.72.1)
#
spdadd 192.168.1.0/24 10.42.23.0/24 any -P out ipsec
       esp/tunnel/172.16.72.1-172.16.72.254/require
       ah/tunnel/172.16.72.1-172.16.72.254/require;

spdadd 10.42.23.0/24 192.168.1.0/24 any -P in ipsec
       esp/tunnel/172.16.72.254-172.16.72.1/require
       ah/tunnel/172.16.72.254-172.16.72.1/require;

Let's start with the first spdadd line. It tells the kernel the following: if you see a outbound packet going from our network 192.168.1.0/24 to the network 10.42.23.0/24, then use IPsec encapsulation and transport the encapsulated data from our external address 172.16.72.1 to the machine with the address 172.16.72.254. The keyword require tells the kernel that IPsec encapsulation is mandatory. The second line defines how to handle the return traffic. Rephrased it says: if you see an IPsec encapsulated inbound packet coming from the network 10.42.23.0/24 and going to our network 192.168.1.0/24 and this packet is coming from the gateway 172.16.72.254 to our external address, then undo the IPsec encapsulation. These are the policies we need for our tunnel. It sounds complicated, but if you take the diagram and trace the packet flow, you will see that it is just a description of what the kernel should do. We now need the keys. We'll reuse the ones from the last article.

# AH SAD entries with 160 bit keys
add 172.16.72.254 172.16.72.1 ah 0x200 -A hmac-sha1 0x46915c30ed7e2465b42861b6ab19f2772813020c;
add 172.16.72.1 172.16.72.254 ah 0x300 -A hmac-sha1 0xc4dac594f8228e0b94a54758f7fbf2fdf4e37f3e;

# ESP SAD entries with 192 bit keys
add 172.16.72.254 172.16.72.1 esp 0x201 -E rijndael-cbc 0xa3993b3dfc41ef0a1aa8d168a8bf2c27e48249ac17b61e09;
add 172.16.72.1 172.16.72.254 esp 0x301 -E rijndael-cbc 0x8f6498928ba354bd45cfad147f54c67b3b742896b3bafc02;

Again this tells the kernel which keys to use when to go from one gateway to another. You have one line for outbound traffic and one for inbound traffic. Now go ahead and create the configuration on both gateways. You can create one setkey.conf and mirror source and destination for the other gateway since packet flows are symmetrically reversed. Enter the command

setkey -f /path/to/setkey.conf

on both gateways and try pinging, telnetting or tracerouting to the network "on the other side".

One word about the example setup: I set the gateways' IP addresses so that they're near each other in IP space; this is something you need to do when routing with directly-connected gateways. When using IPsec tunnels, the gateways don't have to be physically connected, and you can create IPsec tunnels between any hosts and networks that "see" each other on layer 3 (IP in our case).

Routing and the Kernel Policy

Maybe you have noticed that we didn't set any routes to the networks we connected. We don't need to. We told the kernel already what to do with the packets. The Security Policy Database takes care of the packets' path. This behaviour has some implications you have to consider. First, whenever using IPsec tunnels your networks can be "contaminated" by packets with an origin IP outside your network. This is actually what you usually want, but it is very important to consider it in order to implement good access control. If a server in network B only expects and allows connections to be from 10.42.23.0/24, then clients in network A cannot access these services. This can be either good or bad. In any case you have to be aware (and possibly take care) of that. This leads to the second consideration - security. When building one or lots of VPN tunnels, you have to be careful where your endpoints are and what networks they can see.

Automatic Keying and X.509 Certificates

Digging multiple tunnels, dealing with many IPsec clients and keeping track of the keys is a big problem. Consider a gateway that expects IPsec connections from 10 other systems. Then the setkey.conf gets a bit crowded and no one will want to maintain long hexadecimal numbers. In addition to that, pre-shared keys are best used with fixed IP addresses. If you obtain IP addresses dynamically, then you have to think of something else.

Fortunately there is a solution for this problem. The Internet Security Association and Key Management Protocol (ISAKMP) is part of IPsec. It was designed "for establishing Security Associations (SA) and cryptographic keys in an Internet environment", to quote the RFC. It can help us with exchanging keys and creating security policies for the Linux kernel. Key exchange and creation of an IPsec connection are broken up into different phases.

• Phase 1 is a setup phase, also called main mode. The two partners work out how to exchange information securely. They negotiate the encryption method, the hash algorithm, the authentication methods, and a way to securely exchange encryption keys for the next phase. The result of phase 1 is a "security association" that tells both partners how to communicate securely.
• Phase 2 includes the creation of the security policies for the AH and ESP protocols. That's what we already did manually.

During phase 1 the two IPsec partners also check whether they have the right keys to talk to each other. The real data transmission starts after phase 2 is completed.

In order to use ISAKMP you have to configure the racoon daemon. It is also part of the ipsec-tools package. Its configuration file is typically found at /etc/racoon/racoon.conf. We will recreate the tunnel above with racoon in order to get to know the most important configuration directives.

While we are at it, we will swap the pre-shared keys for X.509 certificates. This makes life easier when maintaining multiple keys or issuing VPN access to clients. The certificates are used in the same familiar way as SSL certificates on the World Wide Web, a combination also known as HTTPS (encrypted HTTP). Instead of creating long strings, you simply create a self-signed SSL certificate. Your IPsec gateway(s) check these certificates against the public key of your own Certificate Authority (CA). Every certificate signed by your own CA opens a IPsec tunnel, just like a key would. You can now give these certified keys to every host that is allowed to talk IPsec to you. While this sounds more complicated, it really gets easier when dealing with a lot of IPsec clients.

Automatic Keying in Action

Let's rebuild the last example with racoon. It starts like this:

# racoon.conf file for gateway A
#
path certificate "/etc/racoon/certs";
path pre_shared_key "/etc/racoon/psk.txt";
log notify;
listen {
	isakmp 172.16.72.1 [500];
};

The first directive tells racoon where to look for certificates and certified keys. In our case, this is the directory /etc/racoon/certs. Then we tell the daemon where to look for a collection of pre-shared keys (PSKs). You can use PSKs as well, you don't need to use certificates. The file /etc/racoon/psk.txt holds a list of unique identifiers (such as hostnames or IP addresses) and their corresponding keys.

The next line sets the log level. The log level can be either notify, debug or debug2. Increase the log level if you want to see how racoon creates the IPsec connection. All logging goes to syslog. The listen directive tells racoon where to listen for ISAKMP requests. By default it listens on all devices and on port 500/UDP (the default port for ISAKMP). So far, so good. Now we define the path to gateway B.

remote 172.16.72.254 {
	exchange_mode main;
	generate_policy off;
	passive off;
	certificate_type x509 "gateway.a.example.net.cert" "gateway.a.example.net.key";
	ca_type x509 "ca-cert.pem";
	my_identifier asn1dn;
	peers_identifier asn1dn;
	verify_identifier on;
	proposal {
		encryption_algorithm 3des;
		hash_algorithm sha1;
		authentication_method rsasig;
		dh_group modp1024;
	}
}

Let's walk through the options and see what they mean.

• exchange_mode main - defines the key exchange mode. main is a good choice since it is considered more secure.
• generate_policy off and passive off - when using automatic keying one gateway acts as initiator of the IPsec link. The other gateway remains passive and answers the requests of its peer. By using these two directives we define gateway A to be the initiator of the link. Gateway B need the options generate_policy on and passive on to answer.
• certificate_type and ca_type - indicate the type of certificates we use. We use X.509 certificates and racoon needs to know our key, our certificate and the public certificate of our CA. Even though we're using IP addresses for our gateway definitions, make sure that you use hostnames in the certificates and keys. This is good practice.
• my_identifier and peers_identifier - indicate which identifier should be used to identify hosts or IPsec endpoints. You can use either IP addresses, fully-qualified domain name, ASN.1 distinguished names (ASN.1 DNs) or self-defined IDs. We use ASN.1 DNs since our certificates contain them anyway.
• verify_identifier on - means that we wish to verify our peer's identifier by checking the certificate with our CA.
• proposal - this section holds all information for the phase 1. You can define encryption and hash algorithm, authentication method and Diffie-Hellman exponentiations for secure key exchange. The authentication method is rsasig when using certificates, use pre_shared_key for pre-shared keys.

The man page of racoon.conf has a full list of options and parameters. My example boils down to the bare bones. Keep in mind that we need the configuration above for phase 1 of our connection. We still need to define the security policy for phase 2. This is done in a separate block.

sainfo address 192.168.1.0/24 any address 10.42.23.0/24 any {
        pfs_group modp1024;
        encryption_algorithm aes;
        authentication_algorithm hmac_sha1;
        lifetime time 28800 sec;
        compression_algorithm deflate;
}

The first line announces that the policy is valid for all packets originating in the 192.168.1.0/24 network and going to the 10.42.23.0/24 network.

• pfs_group modp1024 - is used as a parameter for the Diffie-Hellman algorithm.
• encryption_algorithm aes - selects the AES encryption algorithm. You can specify more than one algorithm. One will be chosen during phase 2.
• authentication_algorithm hmac_sha1 - select the authentication algorithm. Again you can specify more than one.
• lifetime time 28800 sec - tells racoon how often this security policy needs to be renegotiated.
• compression_algorithm deflate - selects a compression algorithm. Currently there is only one implemented.

We don't need to define the return path policy since our peer already encapsulates inbound packets with IPsec. That is the whole racoon.conf configuration. You need to have another on gateway B. Make sure that the IP address in the remote section corresponds to the correct peer and that the networks in the sainfo section are reversed. As soon as you have everything in place you can test the setup. Start the racoon daemon on both gateways. On most systems you can do this by issueing the command:

/etc/init.d/racoon start

Check the logs. Most probably not much will happen. The IPsec connection will be initiated by the gateway with the option passive off enabled. Use a client on this gateway's network and create some traffic to the network you wish to connect to via the tunnel. After the first packets are sent, the racoon daemon will start ISAKMP and negotiate through phase 1 and 2. If everything goes well, you can send your first ping packets through the tunnel. The tunnel may needs some seconds to come up. You will get messages such as "resource temporarily unavailable" if the tunnel is not yet ready.

Mobile Tunnels for Roadwarriors

IPsec tunnels are frequently used to connect mobile clients "on the road". They connect to a central gateway, sometimes called a VPN or an IPsec server, and create a secure tunnel. You can use our racoon.conf files with some modifications. Your IPsec server needs to be in passive mode since it's waiting for incoming connections. The connections can originate from anywhere, so your peer will be anonymous.

remote anonymous {
	exchange_mode main;
	generate_policy on;
	passive on;
	certificate_type x509 "vpnserf.example.net.cert" "vpnserf.example.net.key";
	ca_type x509 "ca-cert.pem";
	my_identifier asn1dn;
	peers_identifier asn1dn;
	verify_identifier on;
	proposal {
		encryption_algorithm 3des;
		hash_algorithm sha1;
		authentication_method rsasig;
		dh_group modp1024;
	}
}

The rest of the options can stay the same except for generate_policy and passive. Both need to be enabled. generate_policy tells racoon to create new policies for new connections; this makes sense because our peer varies. The same considerations need to be applied to the security policy in phase 2.

sainfo anonymous {
        pfs_group modp1024;
        encryption_algorithm aes;
        authentication_algorithm hmac_sha1;
        lifetime time 1 hour;
        compression_algorithm deflate;
}

It is a good idea to reduce the lifetime for mobile peers. Again, the parameter anonymous lets racoon accept varying policies. The configuration of the mobile client has to specify the IPsec server's address and the security policy to our internal networks.

Next time we will take a look at filtering IPsec traffic and protecting exposed IPsec servers. Happy digging!

Further Reading

• IPsec HOWTO
• Internet Security Association and Key Management Protocol (ISAKMP)
• IPSec Key Exchange (IKE)
• Certificate Authority (definition)
• Creating a self-signed SSL certificate
• TinyCA

Talkback: Discuss this article with The Answer Gang

---

René was born in the year of Atari's founding and the release of the game Pong. Since his early youth he started taking things apart to see how they work. He couldn't even pass construction sites without looking for electrical wires that might seem interesting. The interest in computing began when his grandfather bought him a 4-bit microcontroller with 256 byte RAM and a 4096 byte operating system, forcing him to learn assembler before any other language.

After finishing school he went to university in order to study physics. He then collected experiences with a C64, a C128, two Amigas, DEC's Ultrix, OpenVMS and finally GNU/Linux on a PC in 1997. He is using Linux since this day and still likes to take things apart und put them together again. Freedom of tinkering brought him close to the Free Software movement, where he puts some effort into the right to understand how things work. He is also involved with civil liberty groups focusing on digital rights.

Since 1999 he is offering his skills as a freelancer. His main activities include system/network administration, scripting and consulting. In 2001 he started to give lectures on computer security at the Technikum Wien. Apart from staring into computer monitors, inspecting hardware and talking to network equipment he is fond of scuba diving, writing, or photographing with his digital camera. He would like to have a go at storytelling and roleplaying again as soon as he finds some more spare time on his backup devices.

Column: IT's Enough To Drive You Crazy

By Pete Savage

Pete has the good fortune to be employed - which includes the bad fortune of having to wrestle with an outdated operating system on a regular basis. In order to stay sane - although some, including perhaps Pete himself, would argue the term strenuously - he a) uses Linux on his own time, and b) rants about his trials and tribulations here in the Linux Gazette, where we're happy to help a fellow Linux user escape the less-sublime facets of his non-Linux reality. (Face it: most of us would drink heavily or kick defenseless puppies. Pete's coping skills rock.)
-- Ben

---

So we come to the second article in the now-serialised, "IT's Enough To Drive You Crazy". I pondered on whether the previous article was a one-off, or whether it was something that would be happening on a regular basis. The optimist inside me cried "One-off, one-off"; the realist, however, took to hiding in a tiny corner of my mind, right after scrawling a hand-written note that said, "You will never escape." Well, give that man a pie - he was actually right. After a short consultation with my editor, he decided that it would probably be beneficial to my psychological state to vent my anger in a quiet and constructive way, such as writing an account of everything that happened. "Like a diary?" I chirped. Exactly. I dug out my Transformers note book, complete with 'Skool is Cool' stickers (remember those?), and prepared to write. I hoped it would take me several days before I would have to write in it. I was wrong.

I was caught early on Monday by a colleague who wanted to print something. On inquiring what was wrong with his printer, I was told that it was broken. On any normal day, this would probably mean that the OS in question would have forgotten what printer was attached, and would probably refuse to acknowledge that any kind of printing device was attached to the computer at all. It gets to the point where sometimes you want to take the advice of some of the computer comedians and plug a webcam into the computer to actually demonstrate how ridiculously stupid it is being. Owing to the fact that I didn't have a webcam, as well as the the imminent danger of my colleague's head exploding, I opted for a more surefire approach: I unplugged the printer from one USB port and plugged it into a different one. The next thing that happened both confused and infuriated me, though it wasn't something that was new to me: the printer was detected and installed as "Canon i9100 (2)". 'But I already have a "Canon i9100"!', I screamed, 'Why can't we use the same one?' There were six USB ports on this machine. I resisted the temptation to try each individual USB port, and put it down to the fact that the machine obviously had disowned USB. Maybe it was fed up with all of those USB 2.0 devices that could perform faster.

To cut a long story short, the printer still didn't print; my colleague's head actually exploded, which almost negated the need for printing the document; the printer ran off whimpering into the corner; and I lost all faith in this OS's ability to handle USB. My decapitated colleague handed me a USB stick. "It's stored on 'ere, can you print t'off that instead?" Does a chicken have wings? I assured him that it would all be fine and that I would have his documents ready on time. Not that it's my job to print them, but I'm a nice guy, right?

Tuesday started worse. I entered my office and sat down at my desk. As part of my morning ritual, I let out a large sigh, which I always seem to do at 7:39 in the morning. I took the USB stick I had been given yesterday, and leaned over to gently insert it into my machine. I ignored the spaghetti-like mess which appeared to be leaking out of all electrical appliances in the office and congregating around my computer. Then, the sort of premonition I described the last time occurred again (I suppose I really must find a name for it - how about a MOIDAF? That is, a Moment Of Impending Doom And Frustration.) I sat back up, took a sip of water and waited for the familiar, "You are obviously too damn lazy to open the drive up yourself, so let me do it for you" prompt to appear. It never did. I took out the USB stick and tried again. Vague memories of the previous day entered my mind and I was forced, against all better judgment, to try another USB port. Still nothing. My machine still sat in a state of some confusion at the object which had just been inserted into it. It seemed to be treating it like some kind of annoying pest, and ignoring it.

I eventually figured out what was wrong. It was simple, really: my computer had suffered a bout of selective amnesia and simply forgot it had a USB device attached at all. How useful. Apparently this kind of thing is not uncommon. If I had been given some kind of explanation for this, I may, and I repeat may, have forgiven it just this once. After a trip to the control panel, the USB port was found again - surprisingly - and all was well. The unanswered question from this experience, however, is "what drove my computer to disown its USB ports in the first place?" I had no logs to check, no way to see what drivers were loaded into the system - and hence, no way to find out what the hell had caused this medical disorder. I do hope it isn't catching. Had I been using my Linux box, I would have a plethora of logs, events, and such. I could have even run an 'lsmod' command to find out what drivers were loaded, followed by the possibility of a 'modprode' command to reload the USB driver. I'm fed up with people inventing excuses for operating systems.

"It's a Thursday. It never works well on a Thursday."
"Everyone else's seems to do the same thing, I thought it was normal for it to do that."
"I think I scared it when I talked about Linux in front of it yesterday."
"It likes to hog all system resources, that's just it's thing."

Why should we as users have to create excuses for an operating system that should be designed with us in mind? [1]

Sorry, you must forgive my pedantic babbling. Some would say it comes with the territory, others would say I'm just a grouch. I like to think I'm somewhere in between. Now, where was I? Ah, yes. Wednesday. It strikes me as odd that this particular problem could have evaded all pursuit as long as it has, through the entire operating system history. I'm not pointing any fingers with this one, primarily because I don't have enough fingers or toes to be able to.

In the company I work for, certain departments collaborate heavily on particular projects, which I must say is excellent and I actively encourage. The problem arose from the requirement to transfer a very large structure of data from one server to another. "A simple copy and paste," I hear you cry, "or a complicated mirror?" This time I opted to just stick with the tried and tested drag-and-drop approach: click on folder with lots of stuff in it. Drag it over folder which has not so much stuff in it. Drop folder. Pray. The copying started and I sat back with a smug feeling of satisfaction, it was 3:30 after all. My satisfaction was short lived (was that really going to be such a surprise?) At 3:32, the copying stopped. Not because it was finished, or because it wanted to take a short coffee break; not because I had told it to, or because it was hungry. No. It stopped because there was a problem. I have a vision of you faithful readers all sitting round me like kids listening to a story at primary school, leaning forward in anticipation. Why did it stop? There was a problem. And this problem was not described well or accurately, no. It was described by one word which throws fear into an IT professionals heart: 'ERROR'.

Turns out it couldn't copy one of the files, aww, bless. So instead of keeping this information safe and carrying on with the rest of the copy routine, it decided to do the sensible thing: cry like a baby and throw the copy operation out of it's pram. I had to spend the next 15 to 30 minutes copying small portions of the tree across till I encountered the error again, then traversing the directory tree and repeating the procedure. It turned out one of the files had a name that was too long. For goodness sake! If you are going to create a file system that people are actually going to use, that's right... real people, not just geeks, why not build in protective routines to prevent this from happening? It's like building a bridge that's only connected to the ground at one end, watching cars go over the other end to their doom and saying, "well, if they will try and go right to the end, what do you expect?" Users are going to try to create files with stupid names like "Letter I wrote to the gas board when they cut my gas off because they said I forgot to pay it, but I thought I had (third time).doc"

<rant>
Users don't sit there and remember the maximum number of characters a file name, including its full path, can have. They don't count characters as they type them or obey conventions by not using spaces and full stops in file names. Users are there to use a computer, I do not believe they should be expected to do their own input validation. After all, that's what a computer is for - isn't it?
</rant>

Don't you just love going into a High Street computer hardware store and quizzing the sales teams? It's fascinating watching them skitter up to people and inquire if they need assistance. If the customer responds in a way that indicates anything other than "I'm just looking, thanks", they lean over towards them with that kind of inquisitive expression normally worn by small rodents. They contort their faces and look confused until they hear one of the buzz words that had been batted around in the training camp. Then they lean back and smile, confident in the knowledge that they have a whole paragraph with which to blind the unsuspecting 68 year old woman buying a joystick for her grandson.

"Oh, you want to buy this one," he'll say. "It's ya basic 3 axis controller with 512 quantization steps in linear movement, complemented with linear throttle control, eight buttons, HAT controller and connects to any standard MPU-401 or USB port if you buy the optional converter. Does your grandson have an MPU-401 port or is it one of the newer USB ports?"
Dear Old Lady: "Well, I just don't know. He got one of these computer somethings for his birthday. He can watch films on it, does that help?"
Salesman: "Hmmm, well if I were you, I'd buy the converter as well. You don't want him to be disappointed, DO YOU? Do you want to purchase our exclusive joystick cleaning cloth as well?"

On this particular day, a Thursday as it happens, I decided to wander into one of these High Street stores. I was looking at a rather strangely shaped case when one of our little friends popped his quivering nose into my face.

"S'a good machine that one. Got the latest Intel Pentium processor with HT technology in it. I've got one at home." I looked at him, with a rather impressed look on my face, trying to hold back the laughter. [2]

"Oh really?" I replied, just begging for more information. "So what does HT stand for?"

His face immediately changed to that of someone try to remove a particularly chewy toffee from their teeth, whilst keeping their mouth shut.

"Hy... Hy... HYPO-THRIDDING!!!" The words suddenly leapt from his mouth. I almost swallowed my chewing gum.

"Hypo-Thridding, eh? So what does this do, compared to one which doesn't have," (I had to say it again) "Hypo-Thridding?" I waited.

"Well it's... just... better, really." He replied.

"Better how?" I asked. I could tell he was near breaking point.

"Well... it's... more expensive, so it has to be better!" was the reply.

"Right... so the fact that, HYPER THREADING, that's HYPER-THREADING, can in certain circumstances increase the performance of the processor by providing usually idle execution units with useful work was just something Intel put in as a bonus, was it?" My little rodent friend scurried away.

Oh, what a week. This was the last day, "only eight hours till the weekend!" I thought. I was wrong. I was called up late in the evening to fix a friend's PC which had a dodgy HDD. He'd purchased a new one and wanted some assistance fitting it and recovering his system. The data was all backed up and I was presented with a fairly easy task - you might think. The HDD was installed without a hitch. I was handed the recovery CD and duly inserted it into the CD drive like the happy little camper I was. Almost the weekend - YAY! I clicked the big recover button, and assured the utility that I was actually aware that doing so would remove all the data from my HDD.

"Sorry, the system doesn't match the original."

My visions of an easy half hour catching up on some reading were shattered. Normally, that's where the journey would end for most non-Linuxian users - but I had a few tricks up my sleeve. I knew the old HDD still functioned but seemed to go haywire every now and then, so I restored the OS back to the old HDD, booted up faithful Knoppix, split the new larger HDD into two partitions using 'fdisk', and used 'dd' to copy the data from the old one back to the new one. Once that had finished, which took several hours owing to the fact that 'dd' copies every bit of data from one drive to the other whether it's being used or not, I simply shut down the machine, removed the old HDD and my flexible friend Knoppix, and booted the PC back up again.

I can hear some of you saying, "but the problem was fixed, Pete. What are you complaining about this time?" I'm complaining about the injustice done to the average non-geek computer user. What do they do when they can't upgrade their computer? Return to vendor to buy new PC. When the HDD breaks and it's no longer under warranty? Return to vendor to buy new PC. I suddenly visualised the massive corporate troubleshooting flow diagram - the flow diagram to end all flow diagrams. It was a highly conceptual diagram, for to print it would have leveled half of the African rain forest. On it was detailed every single problem a user could ever encounter, all of which were gracefully solved. The flow paths wound their way towards the bottom of the flow chart. Which ended in a single instruction. "A single instruction that would solve all problems?" I hear you cry. Yes, I reply.

"Return to vendor to buy a new PC."

---

[1] At this point, I would like to ask if anyone has a good reason why we should be creating these excuses, or if you yourself have a favorite excuse, pass it along to me. You won't win anything, or be given a prize for the best excuse, as chosen by our panel of dysfunctional judges, but you can go away with the feeling that you have helped make the world a better place.

[2] They've always got one at home, ever noticed that? It doesn't matter what product it is, plasma television, kettle, latest games console, portable bread maker, you can go into the shop safe with the knowledge that every salesperson there will have one at home, or have a close relative who's just got one for their birthday. I must be in the wrong job.

Talkback: Discuss this article with The Answer Gang

---

Pete has been programming since the age of 10 on an old Atari 800 XE. Though he took an Acoustical Engineering degree from the world-renowned ISVR in Southampton UK, the call of programming brought him back and he has been working as a Web developer ever since. He uses both Linux and Windows platforms. He still lives in the UK, and is currently living happily with his wife.

HelpDex

By Shane Collinge

These images are scaled down to minimize horizontal scrolling.

Flash problems?

All HelpDex cartoons are at Shane's web site, www.shanecollinge.com.

Talkback: Discuss this article with The Answer Gang

---

Part computer programmer, part cartoonist, part Mars Bar. At night, he runs around in his brightly-coloured underwear fighting criminals. During the day... well, he just runs around in his brightly-coloured underwear. He eats when he's hungry and sleeps when he's sleepy.

The Linux Launderette

---

Contents:

./configure humour

Stupidity

Debian changes its position on the GFDL

Delaveaux

Weather

Interesting mail on the wine-devel list

---

./configure humour

Mon, 13 Mar 2006

From Thomas Adam

The link below was posted into #fvwm by a German speaking person -- my German is like my Russian in that respect: non-existant. Nevertheless I picked out through the bits I understood -- quite amusing. If anyone knows of some others, let us all know.

http://www.linuxforen.de/forums/showthread.php?t=48669&highlight=linux+liebe

---

Stupidity

Wed, 26 Apr 2006

From Jimmy O'Regan

Not even off-topic to this list, but this follows on to, and outdoes, the stupidity I mentioned here: http://linuxgazette.net/124/misc/nottag/dhs.html#trains

See attached stupidity.html

---

Debian changes its position on the GFDL

Tue, 14 Mar 2006

From Jimmy O'Regan

http://trends.newsforge.com/article.pl?sid=06/03/13/1615216&from=rss

They still reject anything that has Invariant Sections, but that's only to be expected.

---

Delaveaux

Mon, 17 Apr 2006

From Marcin Niewalda

Witam [ Translation below ]

[Jimmy] Witamy

Myślę, że to pomyłka: pan napisał do listy adresowego magazynu internetu.

[Jimmy] magazynu internetowego

[Jimmy] Dlatego, że nasz magazyn jest napisany w angielskim,

[Jimmy] napisany po angielsku

[Jimmy] przetłumaczyłem e-mail Pana. Adres, którego Pan szukał, jest Delaveaux@heagmedianet.de ale myślę, że ten pan mowi tylko po angielsku i po niemiecku; a nie wiem, czy ten adres jest nadal aktualny.

[Jimmy] Forgot to translate what I was writing: I think there has been a mistake: you have written to the mailing list of an internet magazine. As our magazine is written in English, I have translated your e-mail. The address you were looking for is [...], but I think that person only speaks English and German, and I don't know if that address is still current.

I'm glad I sprang for the extra thick dictionary

[Ah... see, what happened here is, in issue 64 someone named Roman Delaveaux sent a 2c tip: http://linuxgazette.net/issue64/lg_tips64.html]

Poszukuje genealogicznych informacji o rodzine Delaveaux

[Jimmy] [Searching for genealogical information about the Delaveaux family?]

- Pański mail znalazłem w internecie -

[Jimmy] [I found sir's mail on the internet]

[Jimmy] Hmm. There was probably a typo in the first sentence, which would make the above "While searching for genealogical information about the Delaveaux family, I found your e-mail address on the internet".

czy byłby Pan zainteresowaniem kontaktem ze mną w tej sprawie?.

[Jimmy] [Would sir be interested in contacting me about this matter?]

Nadmieniam że dostałem właśnie informację o niszczejącym grobowcu żony Augusta Delaveaux w Osobnicy.

[Jimmy] [In addition, I have just received information about the spoiling of the tomb of the wife August Delaveaux in particular.]

[Jimmy] of the wife of. It's not every day I get to make errors in two languages in one e-mail

I liked seeing that, as I had been wondering how to 'stack' things in the genitive case, and have only tried to use it once[1]: Beata had told me that her brother's fiancée was visiting, so I said "Musisz pokazywać narzeczoni twojego brata wszystko warto zobaczyć w Thurles'ie, n.p. dworzec kolejowy, ulica do Dublina..." (You must show your brother's fiancée everything worth seeing in Thurles, e.g. the train station, the road to Dublin...)

[1] And it wasn't even the genitive, it was the dative, but for feminine nouns, the dative is the same as the locative, which (aside from a set of exceptions, of course) is the same as the genitive.

And that's one of the easier aspects of Polish grammar :/

Marcin Niewalda

ps. moja praprababcia była z domu De Laveaux

[Jimmy] [ps. My great-great-grandmother was De Leveaux]

ps2. drzewo rodziny Delaveaux przygotowane przeze mnie znajduje się pod adresem http://www.genealogia.okiem.pl/laveaux.htm

[Jimmy] [A Delaveaux family tree prepared by me can be found at this address]

---

Weather

Wed, 19 Apr 2006

From vince werber

Ok... here I go...

The weather IS changing... Why?... the Sun is getting hotter and the sun being a 'star' normally gets hotter as it burns out... Basic physics... Therefore... global warming is real but we have little to do with it...

[Ben] Not Linux, but - destroying the ozone layer, which blocks a large percentage of the damaging UV from the Sun, permits those wavelengths to penetrate our atmosphere. More energy coupled into the system = greater heat. Basic physics, and we have lots and lots to do with it.

Also, that little star we're discussing is about 5 billion years old, and is projected to live to a ripe old 10 billion. Claiming that the weather change over the past couple of years is relevant to the age of the Sun doesn't make a whole lot of sense.

Depressing aren't I??? (I hope anyway...)

[Ben] [grin] Nope. Too many optimists here.

I have often said there are two kinds of mystics, the optimystics and the pessimystics. Now, pessimystics seem to be more in touch with "reality," but optimystics are happier and live longer for some reason. The pessimystics have been crying, "The sky is falling, the sky is falling!" The optimystics say, "No. It just looks that way because we are ascending." -- Swami Beyondananda (Steve Bhaerman)

As for 'the great lizzards'... (Dinosaurs)

[Ben] Are they related to the Great Wizzard?

The stories of my people (Cherokee) claim that we moved south about 15,000 years ago because of an 'ice-age'... such was the ways of 'Turtle Island' (North America) in those times...

[Ben] [blink] The Cherokees claim to have records going back that far? That would be a fascinating new discovery, given that, in general, the reach of recorded (in the roughest sense) human history is considered to be ~13,000 years, at which point (as far as I know) we had not yet spread to the Americas. Africa, however, is indeed supposed to have experienced an "aridity event" lasting from 20,000 to 11,000BC (cooler, drier climate with less rainforest and greater desert spread.)

As for G-d... read and understand what Einstein was saying... Do you think the newly formed Nation of Israel would have even considered a 'non-believer' as their first leader?

[Ben] Um, yeah, actually. Israel was never a theocracy - and Einstein had clearly, repeatedly, and publicly stated his absence of belief in a "personal God".

http://www.infidels.org/library/historical/albert_einstein

[Ben] Modern Israel, I should have said. Not that anyone from a couple of thousand years ago was asking Einstein anything, but still worth clarifying.

[Rick] In fact, the founding fathers of that state in 1948 were overwhelmingly secular people (which is still true of its citizenry to this day), to the point where one of the few religious attendees, Moshe Shapira, tried and failed to get a reference to God into the Declaration of Independence draft, which was vetoed by the majority Labour Party attendees.

Eventually, as a sop to make everyone happy, the concluding sentence was amended to read "With trust in the rock of Israel ["tzur Yisrael" in the original Hebrew text]...."

Shapira was thus free to interpret it as a reference to "the Rock of Israel" (i.e., God), while nearly everyone else could read it as a poetic reference to the territory in question, and historical roots.

Why do I use Slackware? To avoid all of the above and all of those Microsoft 'undocumented features' (bugs)... <heh>

Have a good day and a better tomorrow!

BTW Theory's are just that... theory's... based in air... not provable... Keep the 'truth' and pass me the 'facts'...

[Ben] Erm... I think you've confused the popular and the actual meanings of "theory", Vince. As used by scientists, it means "a well-substantiated explanation of some aspect of the natural world", not "wild guess". However, scientists - in contrast to priests - are willing to learn new and better explanations for natural phenomena, and thus change their theories. This is what intelligent human beings do; this is how our state of knowledge continues to improve.

---

Interesting mail on the wine-devel list

Mon, 13 Mar 2006

From Jimmy O'Regan

http://www.winehq.org/pipermail/wine-devel/2006-March/045546.html

In short, a Microsoft employee mailed a Wine developer asking for help with a function (presumably under the assumption that the Wine developer had written MS's version). Normally, that'd be enough to make me start watching the skies for signs of porcine bombing raids, but the reason the MS guy wrote was to not recommend a customer upgrade to the latest version of Windows!

Talkback: Discuss this article with The Answer Gang

Published in Issue 126 of Linux Gazette, May 2006