November 2010 (#180):

• News Bytes, by Deividson Luiz Okopnik and Howard Dyckoff
• Away Mission - ApacheCon, QCon, ZendCon and LISA, by Howard Dyckoff
• Enemy Action, by Henry Grebler
• House, Lies and Sysadmin, by Henry Grebler
• Installing/Configuring/Caching Django on your Linux server, by Anderson Silva and Steve 'Ashcrow' Milner
• Ten Tips to Harden Your Website, by Sander Temme
• HelpDex, by Shane Collinge
• Ecol, by Javier Malonda
• XKCD, by Randall Munroe
• Doomed to Obscurity, by Pete Trbovich

News Bytes

By Deividson Luiz Okopnik and Howard Dyckoff

Contents: News in General Conferences and Events Distro News Software and Product News

Selected and Edited by Deividson Okopnik

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. Deividson can also be reached via twitter.

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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.

Away Mission - ApacheCon, QCon, ZendCon and LISA

By Howard Dyckoff

Away Mission - ApacheCon, QCon, ZendCon and LISA

This November has a surfeit of superior conferences, most actually running in the first week. The conferences listed in the title all start on Nov 1st which might force you to make some hard choices.

I'll be putting notes on ApacheCon after ZendCon and QCon, but not out of a preference; instead, it's simply in order of shortest commentary to longest. These are all great events and we could even include the Linux Kernel Summit, which is also the first week of November, but we haven't attended one before.

LISA

Unlike the conferences reviewed below, LISA - the Large Installation System Administrator conference organized by USENIX - is during the second week of November and has few conflicts with other events. This is an event with a long history, dating back to the '80s and predating the Internet boom. Indeed, this is the 24th LISA conference. The focus nowadays is on the backends for companies like Google, Yahoo, and Facebook.

I haven't attended a LISA conference since I was a sysadmin, before the beginning of the millennium, but I fondly remember having an opportunity to talk with other sysadmins who were working on the bleeding edge of data center operations. This is the first LISA actually in the San Francisco area, even though USENIX is headquartered in Berkeley. Most West Coast LISA events have been held in San Diego.

Presentations at LISA cover a variety of topics, e.g. IPv6 and ZFS, and training includes Linux Security, Virtualization, and cfEngine among others. Topics covered by the invited presenters include:

• "10,000,000,000 Files Available Anywhere: NFS at Dreamworks," by Sean Kamath and Mike Cutler, PDI/Dreamworks
• "Operations at Twitter: Scaling Beyond 100 Million Users," by John Adams, Twitter

You can find online proceedings from LISA going back to 1993 here.

ZendCon 2010

The 6th Annual Zend/PHP Conference will bring together PHP developers and IT staff from around the world to discuss PHP best practices. This year it will be held at the Santa Clara Convention Center which has lots of free parking and is convenient to Silicon Valley and the San Jose airport. It starts on November 1st and - unfortunately - conflicts with QCon in San Francisco and ApacheCon in Atlanta.

This used to be a vest-pocket conference at the Hyatt near the San Francisco airport and was much more accessible from that city. There was a charm in its smallness and its tight focus and it brought the PHP faithful together with the Zend user community.

This year, ZendCon will host technical sessions in 9 tracks plus have in-depth tutorials and an enlarged Exhibit Hall (with IBM, Oracle and Microsoft as major sponsors). A variety of tracks - SQL, NoSQL, architecture, lifecycle, and server operations - are available. This is an opportunity to learn PHP best practices in many areas.

There will also be an unconference running the 2nd and 3rd days of ZendCon, featuring both 50 minute sessions and 20 minute lightning talks. There is also a CloudCamp unconference on the evening of the tutorial day where early adopters of Cloud Computing technologies exchange ideas. And the 3 days of regular conferencing, without tutorials, is only a modest $1100 before it starts. Not a bad deal either way.

If you want to look for the slides from ZendCon 2009, they can be found here; to listen to the audio recordings being released as a podcast, take a look here.

QCon 2010

QCon is a personal favorite of mine because of its breadth and its European roots. The mix of advanced Agile discussions with Java and Ruby programming and new database technology is intoxicating. Its also a place to see and hear something not repeated at other US conferences.

This year, tracks include Parallel Programming, the Cloud, Architectures You Never Heard Of, Java, REST, Agile process, and NoSQL. Check out the tracks and descriptions here.

Last year, the Agile track (and the tutorials) included several sessions on Kanban as form of 'Lean' and 'Agile' development methodology. Kanban is derived from the signaling used to control railroad traffic and uses token-passing to optimize queues and flows. The idea is to do the right amount of work to feed the next step in the process. An example of a Kanban work flow can be seen in the anime feature "Spirited Away" by Hayao Miyazaki, where a ghostly bath house regulates the use of hot water by passing out use tokens. That way the capacity of the system is never exceeded.

To get info on last year's event, including videos of Martin Fowler and Kent Beck speaking, visit this link.

ApacheCon 2010

I was pleasantly surprised to find this 'Con so close to home since it is held in Boston half the time. The Oakland Convention Center is an underutilized gem in the redeveloped Oakland downtown, very close to the regional Bay Area Rapid Transit station and many fine eateries in Oakland's burgeoning new cuisine district. And the weather is warmer than in San Francisco.

ApacheCon spanned an entire week in 2009. The training period started the week with 2 days of half day classes. This was paralleled by 2 days of Bar Camp - the Unconference that is `included in ApacheCon' - as well as a Hackathon, which in this case was a kind of code camp for project submitters.

This was the first year that the Bar Camp and Hackathon paralleled the training days. Since these two programs were 'free' as in beer, it afforded a chance for many local developers to get involved; it also drew several folk who had never been to ApacheCon. It was also the 10th anniversary of the Apache Software Foundation and there was a celebration during the conference.

Sessions were 50 min long and spanned 4 consecutive tracks. The track content varied over the 3 days of ApacheCon and included many prominent Apache projects. Some presentations were a bit dry and concerned with the details and philosophy of ongoing projects. Some were report cards on the progress of joint efforts with industry and academia.

I attended sessions on Tomcat and Geronimo as well as Axis and other Apache projects. These were very detailed and informative.

The Lightning Talks are short sessions held the last night of the conference. This ApacheCon variant is up to 5 minutes, on anything you want. The limited rules state "No Slides and No Bullets" (as there would be in presentations.) They provide the beer and wine. And they encourage recitals - its supposed to be fun... And they were.

The closing keynote was by Brian Behlendorf, titled "How Open Source Developers Can (Still!) Save The World". Behlendorf was the primary developer of the Apache Web server and a founding member of the Apache Group and is currently a Director of CollabNet, the major sponsor of Subversion and a company he co-founded with O'Reilly & Associates.

He spoke about the important contribution developers can make to non-profits and noted that he is on the board of Bentech, which provides the Martus encryption tools to the human rights and social justice sector to assist in the collection, safeguarding, organization, and dissemination of information about human rights violations. Martus Server Software accepts encrypted bulletins, securely backs them up and replicates them to multiple locations, safeguarding the information from loss. The software was used in the Bosnia war crimes trials.

Among other non-profit development projects, Behlendorf mentioned PloneGov.org which produces modules for Plone to implement common services (like a city meeting template). The aim is to make government more transparent and more efficient.

Behlendorf also mentioned Sahana, a part of Sri Lankan Apache Community that was started after 2004 Tsunami to help relocated survivors. This effort has now resulted in a disaster relief management package used in 20 cities. The UN is starting to use it as this was a space neglected by commercial software corporations.

His summary points: we geeks have skills that are worth more than just dollars and hours to non-profit organizations. So find a project and help out, even non-code contributions can matter.

This year's ApacheCon will be held in Atlanta starting on November 1st. Sessions will feature tracks on Cassandra/NoSQL, Content Technologies, (Java) Enterprise Development, Geronimo, Felix/OSGi, Hadoop + Cloud Computing, Tomcat, Tuscany, Commons, Lucene, Mahout + Search, Business & Community. Free events include a 2-day BarCamp and the evening MeetUps. For more info, visit http://na.apachecon.com/c/acna2010/.

Lunches were boxed on most conference days, but the last day had hot pizza and pasta with great desserts so it was worth lasting out the conference. Also, all the vendor swag was piled on a table for the taking on the last afternoon - so with ApacheCon, patience is a virtue.

The wiki for ApacheCon has some links for presentation slides, but not after the European ApacheCon that preceded the North America ApacheCon in 2009. See here.

SalesForce, DreamForce

If you are interested in Cloud Computing, consider the user conference for SalesForce.com, the annual DreamForce event in San Francisco. It was a November event in 2009 but will happen on December 6-9 this year. There are usually a few open source vendors at the DreamForce expo.

[ The Away Mission Column will be on holiday leave next month. ]

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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.

Enemy Action

By Henry Grebler

	"Once is happenstance. Twice is coincidence. Three times is
	enemy action." 
			- Ian Fleming (spoken by Auric Goldfinger)

Once

Sometimes I buy tickets on the Internet. About a month ago, I bought tickets to the footy. There are several options, but I choose to get the tickets emailed to me as a PDF. I have no idea what research the ticketing agencies do, but they obviously do not include me in the profile of their typical user.

I planned to go with a friend, Jeremy, who supports the opposition team. Jeremy is in paid employment, whereas I am currently "between engagements". He intended to ride his bicycle to the stadium; I would take the train. I agreed to meet Jeremy inside the stadium.

But I've still got to get him his ticket.

Sometimes the tickets come as separate PDF files, but this time they were both in a single PDF. I struggled mindlessly for some time and eventually sent Jeremy a 6.5 MB .ppm! Fortunately, it gzipped very nicely and the email was less than 350 KB.

Twice

Recently, I bought more tickets for some future footy game. Again, they came as a single PDF. This time it was Mark and Matt to whom I wanted to send tickets.

I went to my help directory to see what I had done the previous time. Nothing. As disciplined as I try to be, I remain disappointingly human.

Never mind. I've had lots of time living with myself. I now know there are two of me. I've learnt to put up with the hopeless deficiencies of the Bad Henry. After all, what can you do?

So, I worked out (again!) how to split out pages from a PDF. Between the first and second time, I'd been on a ten-day trip to Adelaide. Before I leave home on long trips I shut down my computer. And my brain.

My solution this time involved PostScript files. I wrote it up (Good Henry was in charge). Then, for completeness (Good Henry can be quite anal), I reconstructed what I probably did the first time and wrote that up also.

Three times

Today it happened again. Last night I booked tickets for the theatre. (You see? There's more to me than just football.) When I looked at the tickets, I found a single PDF containing 4 tickets: two for me and my wife, two for Peter and his wife, Barbara.

And finally I hit the roof. I'd tried Adobe Acrobat, xpdf, and evince. They all have the same problem: they insist on honouring the stupid restrictions included in the PDF, things like "no copying".

	Encrypted:      yes (print:yes copy:no change:no addNotes:no)

Think about it. How stupid is this? If I have x.pdf, no matter what some cretin includes in the file, nothing can stop me from going:

	cp x.pdf x2.pdf

So what has been achieved by the restriction? The words of the song about the benefits of war come to mind: absolutely nothing! And I am tempted to say it again: absolutely nothing.

[ These days, there are so many ways to remove/bypass/eliminate/ignore that so-called "protection" - e.g., ensode.net's online "unlocker" - that it is indeed meaningless. -- Ben ]

So let's say I send Jeremy or Mark or Matt a copy of the entire PDF. What I'm concerned about is that they may inadvertently print the wrong ticket. Sure, in the email, I tell each person which ticket is his. But... since each ticket has a barcode, perhaps the stadium checks and complains about a second attempt to present the same ticket. Embarrassment all round.

Notice that I'm not trying to do anything illegal or underhanded. I'm not trying to violate some cretin's digital rights. I'm not trying to harm anyone. I'm trying to get a ticket to my friend; a ticket that I bought legitimately; one that I'm not only entitled, but required, to print out. I guess they want me to fax it to him. But isn't that also making a copy? Do they expect me to drive across town to get him his ticket?

It seems to me amazing that I'm the only one who wants this capability. Every time I've looked on my computer (apropos) or anywhere else (Internet), I've never found a convenient mechanism. I now have a mechanism (see next section), but this is really a plea for help. Can anyone suggest something a little more elegant than what I've come up with?

2-Cent Tip

Here is the best method I could come up with for extracting one page, or several contiguous pages, from a PDF into a separate PDF:

	gs -dSAFER -sDEVICE=pdfwrite -dNOPAUSE -dBATCH \
		-dFirstPage=3 -dLastPage=4 \
		-sOutputFile=PeterAndBarbara.pdf Tickets.pdf

Basically this command says to extract pages 3 and 4 from Tickets.pdf and put them into PeterAndBarbara.pdf. The first line consists mainly of window dressing.

If you want to extract each page as a separate PDF file (not a bad idea), here's a script:

#! /bin/sh
#       pdfsplit.sh - extract each page of a PDF into a separate file

        myname=`basename $0`

#----------------------------------------------------------------------#
Usage () {
        cat <<EOF
Usage: $myname file

where   file    is the PDF to split

Output goes to /tmp/page_n.pdf
EOF
        exit
}

#----------------------------------------------------------------------#
Die () {
        echo $myname: $*
        exit
}

#----------------------------------------------------------------------#
        [ $# -eq 1 ] || Usage

        pages=`pdfinfo $1 | grep Pages | awk '{print $2}'`
        [ "$pages" = '' ] && Die "No pages found. Perhaps $1 is not a pdf."
        [ "$pages" -eq 1 ] && Die "Only 1 page in $1. Nothing to do."

        jj=1
        while [ $jj -le $pages ]
        do
                gs -dSAFER -sDEVICE=pdfwrite -dNOPAUSE -dBATCH \
                        -dFirstPage=$jj -dLastPage=$jj \
                        -sOutputFile=/tmp/page_$jj.pdf $1
                jj=`expr $jj + 1`
        done

Notes

You can look at gs(1) for a limited amount of help. For more useful help, do this:

	gs -h

and look at the second last line. Mine says:

	For more information, see /usr/share/ghostscript/8.15/doc/Use.htm.

I've probably broken my system, because it is actually in /usr/share/doc/ghostscript-8.15/Use.htm. Another system refers correctly to /usr/local/share/ghostscript/8.64/doc/Use.htm.

You can use your usual browser or you can use:

	lynx /usr/share/doc/ghostscript-8.15/Use.htm

See also pdfinfo(1). Here's an example of its output:

pdfinfo Tickets.pdf
Producer:       Acrobat Distiller 7.0.5 (Windows)
CreationDate:   Tue Mar 16 04:21:58 2010
ModDate:        Tue Mar 16 04:21:58 2010
Tagged:         no
Pages:          4
Encrypted:      yes (print:yes copy:yes change:no addNotes:no)
Page size:      595 x 842 pts (A4)
File size:      1290313 bytes
Optimized:      no
PDF version:    1.4

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House, Lies and Sysadmin

By Henry Grebler

In the TV show House, the eponymous protagonist often repeats the idea that patients lie.

"I don't ask why patients lie, I just assume they all do."

If you're in support, you could do worse than transpose that dictum to your users. Of course, I'm using "lie" very loosely. Often the user does not set out to deceive; and yet, sometimes, I can't escape the feeling that they could not have done a better job of deception had they tried.

Take a case that occurred recently. A user wrote to me. I'll call him Gordon.

	Hi Henry,

	I'm embarrassed to say that I seem to have lost (presumably
	deleted) my record of email for the AQERA association while
	re-organizing email folders earlier this year.

	The folder was called Assoc/AQERA, and I deleted it around May
	18 of this year. Would it be possible to recover the folder
	from a time point shortly before that date?

	Thanks a lot
	Gordon

This was written in early September. That's Gordon's first bit of bad luck. We keep online indexes for 3 months. Do the math. A couple of weeks earlier, and I might have got back his emails with little trouble - and this article would never have been born.

	Hi Gordon,

	The difficult we do today. The impossible takes a little
	longer.

	Your request falls into the second category.


	Cheers,
	Henry

Some customers have unrealistic expectations. Gordon is remarkably understanding:

	Err, does that mean not possible, or that it will take a
	while?

	I understand it might not be not recoverable, and it's my own
	fault anyway, but I need to know.

Who knows what might have happened under normal circumstances? In this case, there were some unusual elements. I'd started work at this organisation May 10. Less than 2 weeks later, our mail server had crashed. When we rebooted, one of the disk drives showed inconsistencies which an fsck was not able to resolve (long story). We had to go back to tapes and recover to a different disk on a different machine and then serve the mail back to the first machine over NFS.

The disk drive which had experienced the inconsistencies was still attached to the mail server. I would often mount it read-only to check something or other. In this case, I checked to see if the emails he wanted were on that drive. They weren't. The folder wasn't there.

There were other folders in the Assoc/AQERA family (Assoc/AQERA-2010, Assoc/AQERA-20009, etc). But no Assoc/AQERA.

There was something else that was fishy. I can't remember the exact date of the mail server crash. Let's say it was May 24. When we recovered from backup, we would have taken the last full backup from the first week in May. In other words, we would have restored his account back to how it was before May 18. Without meaning to, we would have "undeleted" the deleted folder his email claimed.

For many reasons, after the email system was restored, users did not get access to their historical emails until early June.

So something he's telling me is misleading. Either he deleted the folder before the beginning of May or after the middle of June. Or, perhaps, it never existed. If I had online indexes going back far enough, I could answer all questions in a few minutes. Without them, I'm up for really long tape reads. My job is not about determining where the truth lies, it's about recovering the emails.

I wrote to Gordon, explaining all this and added:

	So, before I embark on a huge waste of time for both of us, I
	suggest we have a little chat about exactly when you think you
	deleted the folder, and exactly what its name is.

I suppose we had the discussion. A day or two later he wrote again:

	Here's another thought, that I hope will save work rather than making 
	more.

	I didn't notice that I was missing any mail until about 1
	September. At that time I went to my mailbox
	Assoc/AQERA-admin, which should have in principle contained
	hundreds of emails, but actually contained only one.

	If there any recent backup in which Assoc/AQERA-admin contains
	more than one or two emails, then those are the emails I'm
	after.

And that was all I needed!

Stupidly, I followed the suggestion in his last paragraph - and drew a blank. But then I went back to the failed disk and searched for Assoc/AQERA-admin (rather than the elusive Assoc/AQERA).

	I have found a place with the above directory which contains
	843 emails dating back to 2003. I have restored it to your
	mailbox as Assoc/AQERA-admin-May21 (in your notation).

	I hope this helps.

And this is how I know my customers love me:

	Fantastic!!

	That's everything I was after. Recovering this mail will make
	my job as AQERA president much easier over the next year.

	Many thanks
	Gordon

It's why I put up with the "lies" and inadvertent misdirections. I have an overwhelming need to be appreciated. At heart, I'm still at school craving any sign of the teacher's approval. It may have made me a superb student. But what does it say for my self-esteem? Who's the more together human being? Me? Or my son, whom I tried to shame into doing better? He didn't care tuppence for his teacher's approval. Or mine. And yet, here he is, doing third-year Mechatronics Engineering at uni.

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Installing/Configuring/Caching Django on your Linux server

By Anderson Silva and Steve 'Ashcrow' Milner

In today's world, web development is all about turnaround. Businesses want to maximize production outcome while minimizing development and production time. Small, lean development teams are increasingly becoming the norm in large development departments. Enter Django: a popular Python web framework that invokes the RWAD (rapid web application development) and DRY (don't repeat yourself) principles with clean, pragmatic design.

This article is not about teaching you how to program in Python, nor how to use the Django framework. It's about showing how to promote your Django applications onto an existing Apache or Lighttpd environment.

We will conclude with a simple way that you can improve the performance of your Django application by using caching to speed up access time. This article also assumes that you are running Fedora as your web application server, but all the packages mentioned in this article are also available in many OS's including under the Extra Packages for Enterprise Linux repository, which means these instructions should also be valid under Red Hat Enterprise Linux or CentOS servers.

What you need

You must have Django installed:

$ yum install Django

If you want to serve Django apps under Apache you will need mod_wsgi:

$ yum install httpd mod_wsgi

If you want to serve Django apps under Lighttpd:

$ yum install lighttpd lighttpd-fastcgi python-flup

Installing memcached to 'speed up' Django apps:

$ yum install memcached python-memcached

Starting a new Django project

1. Create a development workspace.

$ mkdir -p $LOCATION_TO_YOUR_DEV_AREA 
$ cd $LOCATION_TO_YOUR_DEV_AREA

2. Start a new base Django project. This creates the boiler plate project structure.

$ django-admin startproject my_app

3. Start the Django development web server on port 8080 (or whatever other port you'd like).

Note: The development web server is just for testing and verification. Do not use it as a production application server!

$ python manage.py runserver 8080

4. Run your Django project under Apache with mod_wsgi by enabling mod_wsgi. Note that to do this you will need to have your project in an SELinux friendly location (don't use home directories!) as well as readable by apache. On Fedora mod_wsgi is auto added upon install via /etc/httpd/conf.d/wsgi.conf. Upon restarting of apache, the module will be loaded.

5. Create virtual hosts by creating a new file at /etc/httpd/conf.d/myapp.conf.

WSGIScriptAlias / /path/to/myapp/apache/django.wsgi

DocumentRoot /var/www/html/
ServerName your_domain_name
ErrorLog logs/my_app-error.log
CustomLog logs/my_app-access_log common

import os
import sys

import django.core.handlers.wsgi

# Append our project path to the system library path
sys.path.append('/path/to/')

# Sets the settins module so Django will work properly
os.environ['DJANGO_SETTINGS_MODULE'] = 'myapp.settings'

# sets application (the default wsgi app) to the Django handler
application = django.core.handlers.wsgi.WSGIHandler()

Running your Django project under Lighthttpd with fastcgi

The first thing you must do is start up your FastCGI server.

./manage.py runfcgi method=prefork socket=/var/www/myapp.sock pidfile=django_myapp.pid

Then modify your lighttpd.conf file to use the FastCGI server.

server.document-root = "/var/www/django/"
fastcgi.server = (
    "/my_app.fcgi" => (
        "main" => (
            # Use host / port instead of socket for TCP fastcgi
            # "host" => "127.0.0.1",
            # "port" => 3033,
            "socket" => "/var/www/my_app.sock",
            "check-local" => "disable",
        )
    ),
)
alias.url = (
    "/media/" => "/var/www/django/media/",
)
url.rewrite-once = (
    "^(/media.*)$" => "$1",
    "^/favicon\.ico$" => "/media/favicon.ico",
    "^(/.*)$" => "/my_app.fcgi$1",
)

Setting up caching in Django

Django has many different caching backends, including database, memory, filesystem, and the ever popular memcached. According to http://www.danga.com/memcached/, memcached is "a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load." It's used by high traffic sites such as Slashdot and Wikipedia. This makes it a prime candidate for caching in your cool new web app.

First, install memcached.

$ yum install memcached

Next, install the python bindings for memcached.

$ yum install python-memcached

Next, verify that memcached is running using the memcached's init script.

$ /etc/init.d/memcached status 
memcached (pid 6771) is running...

If it's not running, you can manually start it.

$ /sbin/service memcached start

If you want to make sure it will automatically start every time after a reboot:

$ /sbin/chkconfig --level 35 memcached on

Now that you have verified that memcached is running, you will want to tell your Django application to use memcached as it's caching backend. You can do this by adding a CACHE_BACKEND entry to your settings.py file.

CACHE_BACKEND = 'memcached://127.0.0.1:11211/'

The format is "backend://host:port/" or "backend:///path" depending on the backend chosen. Since we are using memcached, we have the option to run multiple daemons on different servers and share the cache across multiple machines. If you want to do this all you must do is add in the servers:port combinations in the CACHE_BACKEND and separate them by semicolons. In this example we share the cache across three different memcached servers:

CACHE_BACKEND = 'memcached://127.0.0.1:11211;192.168.0.10:11211;192.168.0.11/'

For more information on the different types of caching that can be performed in the Django framework, please refer to their official documentation.

Finally, whenever you are ready to get your applications into production, you can always write your own Django service script, so your application can start up at boot time.

The original article was published on June 5th, 2008 by Red Hat Magazine, and revised for the 2010 November Issue of Linux Gazette.

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Ten Tips to Harden Your Website

By Sander Temme

Sander will be presenting “Hardening Enterprise Apache Installations Against Attacks” and is Apache HTTP Server Track Chair at ApacheCon, the ASF’s official conference, training, and expo, taking place 1-5 November 2010 in Atlanta, Georgia.

Introduction

Websites are under continuous attack. Defacement, malware insertion and data theft are but a few of motivators for the attackers, and anyone who runs an Internet-facing website should be prepared to defend themselves.

Website owners have many tools at their disposal with which to thwart online attackers; entire books have been written about this field. Here are ten tips that will quickly improve the security of your website.

1. Harden your Operating System

The default installation of your server operating system likely comes with a number of features you would not use. Turn off operating system services that are not used by your web application. Be especially wary of running anything that exposes a network listener (a network listener is a system task that listens on a given network port for incoming client connections). Uninstall software packages you do not use, or opt not to install them in the first place: the smaller your software installation, the smaller the attack surface. Use the extra security features offered by your operating system like SELinux or BSD securelevel. For instance, default SELinux configuration on Red Hat Enterprise Linux strikes a good balance where server programs that listen on the network are locked down tightly (which makes sense), but regular system maintenance utilities have the run of the system (because locking them down would be very complex to configure and maintain).

2. Use Software and Operating System that You can Maintain

The idea that one vendor’s operating system is inherently more secure than any others is largely a myth. You do not achieve increased security just by picking an operating system and then forgetting about it. Every operating system environment is subject to vulnerabilities, which get fixed and patched over time. Run your website on an operating system that you and your organization are comfortable maintaining and patching: a well maintained, up-to-date Windows server may well be more secure than a stale, unmaintained Linux installation. Your task is to maintain and defend your website, not to engage in a religious war of one operating system versus another.

3. Slim Down your Server Software

When first installed, the default configuration of server software is often intended to be a feature showcase, rather than an Internet facing deployment. Turn off unused Apache modules. Slim down your server configuration file: only include configuration directives for functionality that you actually use. Remove sample code, default accounts and manual pages: install those on your development system. Turn off all error reporting to the browser. A lean server configuration is easier to manage, and presents attackers with less opportunity.

4. Access your Management Interface over SSL

Many website environments and Content Management Systems are managed through an interface that is part of the website itself. Consider running this part of your site over SSL to protect login credentials and other sensitive data. An SSL-enabled website is protected by a cryptographic key and certificate that identify the server. You do not need to buy an expensive certificate to do this: generate your own certificate and add it to the trusted certificate store of your browser: as website manager, you are the only one who needs to trust your own certificate. Content Management Systems like Wordpress allow you to enable SSL on the management interface with a few configuration settings. Encrypting management connections with SSL is an effective way to protect your all-important login credentials.

5. White-list Allowed Actions, Blacklist Attacks

As site manager, you should know which legitimate HTTP operations users can perform on your site. Ideally, you should treat any other action as hostile, and deny it. Unfortunately, this is not always feasible or politically achievable: you may have inherited an environment in which all the valid URL and operation combinations are simply unknown, and aggressive restrictions may interfere with business operations. On the Apache web server, you can use a Web Application Firewall like ModSecurity by Ivan Ristic to allow and disallow access to particular URLs and actions. Other web server software packages provide similar features. If you are unable to white-list allowed actions, you should be able to blacklist attacks as you see them happen.

6. Use a Firewall

After a web application is compromised, the attackers will often attempt to have the application download additional malware. Or, installed malware may connect to a command-and-control server hosted elsewhere. Generally, a web application should only respond to incoming requests, and not be allowed to make outgoing TCP connections. This makes server maintenance a little more cumbersome, but it is a small price to pay for stopping attackers’ operations.

7. Keep your Software Up-to-date

Vulnerabilities are discovered on a regular basis in every operating system and on all application platforms. Fortunately, once discovered, they are usually fixed reasonably swiftly. Be sure to keep your system and software up-to-date and install all vendor patches.

8. Peruse your Logs

Your web server will log every request it handles, and will note any errors that occur. An attempt to attack your web server will likely leave a rash of error messages in your server logs, and you should monitor those logs on a regular basis to see how you are being attacked. Log monitoring can also reveal URLs and operations that initiate attacks and should be blacklisted.

9. Prevent Writing to Document Root

Your website might serve two types of content: content that you put there, and content that someone else puts there unbeknownst to you. The Internet-facing network listener that provides access to your application is its lifeline: without it your application would not be usable. However, it is also an attack vector. Through specially crafted HTTP requests, attackers will probe vulnerabilities in your application and configuration. They will try to upload content or scripts to your website: if they can get a PHP script uploaded and call it through the web server, it runs with the same privileges as the web server program and can likely be used to wreak havoc.

Content Management Systems like Joomla! and Wordpress allow site managers to upload and update plug-ins, and in some cases, to configure the server-side software through a web browser. This makes these packages really easy to use, but the drawback is that the web server program must be able to write to the server directories that contain the software. This capability is easily abused by intruders. Never allow the web server program to write to directories within the URL space of the site, where uploaded content can be served and possibly called as interpreted scripts. Instead, upload your software and plug-ins through an out-of-band mechanism like SSH or SFTP.

10. Use One Time Passwords

Abuse of login credentials is often a more successful attack method than exploitation of software vulnerabilities. Active Internet users often have dozens of User IDs and passwords on dozens of different websites. Expecting users to follow the recommendations concerning password strength and change frequency is unrealistic.

However, if there is one site for which you use strong passwords that you change on a regular basis, make it your own website management interface.

An even better way to protect login credentials is through use of One Time Passwords. This method lets you calculate a new password for every time you log into your site management interface, based on a challenge sent by the site and a PIN that only you know. Programs to calculate One Time Passwords are available for all operating systems, including smart phones, so you can carry your OTP generator with you and separate it from the network interaction with your website. Since an OTP can never be used twice, this technique makes your website management interface immune to keystroke loggers and network sniffers: even if your login information is sniffed or captured, the attackers cannot re-use it.

Conclusion: Use “The CLUB™”

The CLUB™ is a lock that you put on the steering wheel of your car as you park it. It is inexpensive and clearly visible to anyone who might consider breaking into your car and stealing it. In addition, it will encourage miscreants to skip your car and move on to a car that does not have a visible security device. Making your own car a less attractive target is a highly effective security control technique.

There is a clear analogy to the CLUB™ for defending your website: with a few relatively simple measures like the ones described above, you can thwart the scripts that automatically scan the web for vulnerable sites, and have their owners focus their attention on the many, many websites that lack basic protection.

Of course basic protective measures do not absolve you entirely: your website is likely up 24/7 and unlike car thieves, who operate in a public place, web attackers have all the time in the world to quietly pick away at the locks on your website until they find a weakness they can exploit. As a webmaster, you need to plug all the holes, but the villains need to find only one leak. Therefore, your continued vigilance is required and the tips discussed above should give you a good start.

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HelpDex

By Shane Collinge

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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.

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By Javier Malonda

The Ecol comic strip is written for escomposlinux.org (ECOL), the web site that supports es.comp.os.linux, the Spanish USENET newsgroup for Linux. The strips are drawn in Spanish and then translated to English by the author.

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Doomed to Obscurity

By Pete Trbovich

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