Posts Tagged ‘lenny’

Check and Restart Apache if it is malfunctioning (not returning HTML content) shell script

Monday, March 19th, 2012

Check and Restart Apache Webserver on Malfunction, Apache feather logo

One of the company Debian Lenny 5.0 Webservers, where I'm working as sys admin sometimes stops to properly server HTTP requests.
Whenever this oddity happens, the Apache server seems to be running okay but it is not failing to return requested content

I can see the webserver listens on port 80 and establishing connections to remote hosts – the apache processes show normally as I can see in netstat …:

apache:~# netstat -enp 80
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 xxx.xxx.xxx.xx:80 46.253.9.36:5665 SYN_RECV 0 0 -
tcp 0 0 xxx.xxx.xxx.xx:80 78.157.26.24:5933 SYN_RECV 0 0 -
...

Also the apache forked child processes show normally in process list:

apache:~# ps axuwwf|grep -i apache
root 46748 0.0 0.0 112300 872 pts/1 S+ 18:07 0:00 \_ grep -i apache
root 42530 0.0 0.1 217392 6636 ? Ss Mar14 0:39 /usr/sbin/apache2 -k start
www-data 42535 0.0 0.0 147876 1488 ? S Mar14 0:01 \_ /usr/sbin/apache2 -k start
root 28747 0.0 0.1 218180 4792 ? Sl Mar14 0:00 \_ /usr/sbin/apache2 -k start
www-data 31787 0.0 0.1 219156 5832 ? S Mar14 0:00 | \_ /usr/sbin/apache2 -k start

In spite of that, in any client browser to any of the Apache (Virtual hosts) websites, there is no HTML content returned…
This weird problem continues until the Apache webserver is retarted.
Once webserver is restarted everything is back to normal.
I use Apache Check Apache shell script set on few remote hosts to regularly check with nmap if port 80 (www) of my server is open and responding, anyways this script just checks if the open and reachable and thus using it was unable to detect Apache wasn't able to return back HTML content.
To work around the malfunctions I wrote tiny script – retart_apache_if_empty_content_is_returned.sh

The scripts idea is very simple;
A request is made a remote defined host with lynx text browser, then the output of lines is counted, if the output returned by lynx -dump http://someurl.com is less than the number returned whether normally invoked, then the script triggers an apache init script restart.

I've set the script to periodically run in a cron job, every 5 minutes each hour.
# check if apache returns empty content with lynx and if yes restart and log it
*/5 * * * * /usr/sbin/restart_apache_if_empty_content.sh >/dev/null 2>&1

This is not perfect as sometimes still, there will be few minutes downtime, but at least the downside will not be few hours until I am informed ssh to the server and restart Apache manually

A quick way to download and set from cron execution my script every 5 minutes use:

apache:~# cd /usr/sbin
apache:/usr/sbin# wget -q http://www.pc-freak.net/bscscr/restart_apache_if_empty_content.sh
apache:/usr/sbin# chmod +x restart_apache_if_empty_content.sh
apache:/usr/sbin# crontab -l > /tmp/file; echo '*/5 * * * *' /usr/sbin/restart_apache_if_empty_content.sh 2>&1 >/dev/null

 

How to install nginx webserver from source on Debian Linux / Install Latest Nginx on Debian

Wednesday, March 23rd, 2011

Nginx install server logo
If you're running a large website consisting of a mixture of php scripts, images and html. You probably have noticed that using just one Apache server to serve all the content is not that efficient

Each Apache child (I assume you're using Apache mpm prefork consumes approximately (20MB), this means that each client connection would consume 20 mb of your server memory.
This as you can imagine is truly a suicide in terms of memory. Each request for a picture, css or simple html file would ask Apache to fork another process and will consume (20mb of extra memory form your server mem capacity)!.

Taking in consideration all this notes and the need for some efficiency here, the administrator should normally think about dividing the processing of the so called static content from the dynamic content served on the server.

Apache is really a nice webserver software but with all the loaded modules to serve dynamic content, for instance php, cgi, python etc., it's becoming not the best solution for handling a (css, javascript, html, flv, avi, mov etc. files).

Even a plain Apache server installation without (libphp, mod_rewrite mod deflate etc.) is still not dealing efficiently enough with the aforementioned static files content

Here comes the question if Apache is not that quick and efficient in serving static files, what then? The answer is caching webserver! By caching the regular static content files, your website visitors will benefit by experiencing shorter webserver responce files in downloading static contents and therefore will generally hasten your website and improve the end user's experience.

There are plenty of caching servers out there, some are a proprietary software and some are free software.

However the three most popular servers out there for static file content serving are:

  • Squid,
  • Varnish
  • Nginx

In this article as you should have already found out by the article title I'll discuss Nginx

You might ask why exactly Nginx and not some of the other twos, well simply cause Squid is too complicated to configure and on the other hand does provide lower performance than Nginx. On the other hand Varnish is also a good solution for static file webserver, but I believe it is not tested enough. However I should mention that my experience with testing varnish on my own home router is quite good by so far.

If you're further interested into varhisn cache I would suggest you checkout www.varhisn-cache.org .

Now as I have said a few words about squid and varhisn let's proceed to the essence of the article and say few words about nginx

Here is a quote describing nginx in a short and good manner directly extracted from nginx.com

nginx [engine x] is a HTTP and reverse proxy server, as well as a mail proxy server written by Igor Sysoev. It has been running for more than five years on many heavily loaded Russian sites including Rambler (RamblerMedia.com). According to Netcraft nginx served or proxied 4.70% busiest sites in April 2010. Here are some of success stories: FastMail.FM, WordPress.com.

By default nginx is available ready to be installed in Debian via apt-get, however sadly enough the version available for install is pretty much outdated as of time of writting the nginx debian version in lenny's deb package repositories is 0.6.32-3+lenny3

This version was release about 2 years ago and is currently completely outdated, therefore I found it is not a good idea to use this old and probably slower release of nginx and I jumped further to install my nginx from source:
Nginx source installation actually is very simple on Linux platforms.

1. As a first step in order to be able to succeed with the install from source make sure your system you have installed the packages:

debian:~# apt-get install libpcre3 libpcre3-dev libpcrecpp0 libssl-dev zlib1g-dev build-essential

2. Secondly download latest nginx source code tarball

Check out on http://nginx.com/download the latest stable release of nginx and further issue the commands below:

debian:~# cd /usr/local/src
debian:/usr/local/src# wget http://nginx.org/download/nginx-0.9.6.tar.gz

3.Unarchive nginx source code

debian:/usr/local/src#tar -zxvvf nginx-0.9.6.tar.gz
...

The nginx server requirements for me wasn't any special so I proceeded and used the nginx ./configure script which is found in nginx-0.9.6

4. Compline nginx server

debian:/usr/local/src# cd nginx-0.9.6
debian:/usr/local/src/nginx-0.9.6# ./configure && make && make install
+ Linux 2.6.26-2-amd64 x86_64
checking for C compiler ... found
+ using GNU C compiler
+ gcc version: 4.3.2 (Debian 4.3.2-1.1)
checking for gcc -pipe switch ... found
...
...

The last lines printed by the nginx configure script are actually the major interesting ones for administration purposes the default complation options in my case were:

Configuration summary
+ using system PCRE library
+ OpenSSL library is not used
+ md5: using system crypto library
+ sha1 library is not used
+ using system zlib library

nginx path prefix: "/usr/local/nginx"
nginx binary file: "/usr/local/nginx/sbin/nginx"
nginx configuration prefix: "/usr/local/nginx/conf"
nginx configuration file: "/usr/local/nginx/conf/nginx.conf"
nginx pid file: "/usr/local/nginx/logs/nginx.pid"
nginx error log file: "/usr/local/nginx/logs/error.log"
nginx http access log file: "/usr/local/nginx/logs/access.log"
nginx http client request body temporary files: "client_body_temp"
nginx http proxy temporary files: "proxy_temp"
nginx http fastcgi temporary files: "fastcgi_temp"
nginx http uwsgi temporary files: "uwsgi_temp"
nginx http scgi temporary files: "scgi_temp"

If you want to setup nginx server to support ssl (https) and for instance install nginx to a different server path you can use some ./configure configuration options, for instance:

./configure –sbin-path=/usr/local/sbin –with-http_ssl_module

Now before you can start the nginx server, you should also set up the nginx init script;

5. Download and set a ready to use script with cmd:

debian:~# cd /etc/init.d
debian:/etc/init.d# wget http://www.pc-freak.net/files/nginx-init-script
debian:/etc/init.d# mv nginx-init-script nginx
debian:/etc/init.d# chmod +x nginx

6. Configure Nginx

Nginx is a really easy and simple server, just like the Russians, Simple but good!
By the way it's interesting to mention nginx has been coded by a Russian, so it's robust and hard as a rock as all the other Russian creations 🙂
Nginx configuration files in a default install as the one in my case are to be found in /usr/local/nginx/conf

In the nginx/conf directory you're about to find the following list of files which concern nginx server configurations:

deiban:/usr/local/nginx:~# ls -1
fastcgi.conf
fastcgi.conf.default
fastcgi_params
fastcgi_params.default
koi-utf
koi-win
mime.types
mime.types.default
nginx.conf
nginx.conf.default
scgi_params
scgi_params.default
uwsgi_params
uwsgi_params.default
win-utf

The .default files are just a copy of the ones without the .default extension and contain the default respective file directives.

In my case I'm not using fastcgi to serve perl or php scripts via nginx so I don't need to configure the fastcgi.conf and fastcgi_params files, the scgi_params and uwsgi_params conf files are actually files which contain nginx configuration directives concerning the use of nginx to process SSI (Server Side Include) scripts and therefore I skip configuring the SSI conf files.
koi-utf and koi-win are two files which usually you don't need to configure and aims the nginx server to support the UTF-8 character encoding and the mime.types conf is a file which has a number of mime types the nginx server will know how to handle.

Therefore after all being said the only file which needs to configured is nginx.conf

7. Edit /usr/local/nginx/conf/nginx.conf

debian:/usr/local/nginx:# vim /usr/local/nginx/conf/nginx.conf

Therein you will find the following default configuration:

#gzip on;

server {
listen 80;
server_name localhost;

#charset koi8-r;

#access_log logs/host.access.log main;

location / {
root html;
index index.html index.htm;
}
#error_page 404 /404.html;

# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}

In the default configuration above you need to modify only the above block of code as follows:

server {
listen 80;
server_name yoursitedomain.com;

#charset koi8-r;

#access_log logs/access.log main;

location / {
root /var/www/yoursitedomain.com/html;
index index.html index.htm;
}

Change the yoursitedomain.com and /var/www/yoursitedomain.com/html with your directory and website destinations.

8. Start nginx server with nginx init script

debian:/usr/local/nginx:# /etc/init.d/nginx start
Starting nginx:

This should bring up the nginx server, if something is miss configured you will notice also some error messages, as you can see in my case in above init script output, thanksfully there are no error messages.
Note that you can also start nginx directly via invoking /usr/local/nginx/sbin/nginx binary

To check if the nginx server has properly started from the command line type:

debian:/usr/local/nginx:~# ps ax|grep -i nginx|grep -v grep
9424 ? Ss 0:00 nginx: master process /usr/local/nginx/sbin/nginx
9425 ? S 0:00 nginx: worker process

Another way to check if the web browser is ready to serve your website file conten,t you can directly access your website by pointing your browser to with http://yoursitedomain.com/, you should get your either your custom index.html file or the default nginx greeting Welcome to nginx

9. Add nginx server to start up during system boot up

debian:/usr/local/nginx:# /usr/sbin/update-rc.d -f nginx defaults

That's all now you have up and running nginx and your static file serving will require you much less system resources, than with Apache.
Hope this article was helpful to somebody, feedback on it is very welcome!

Problems during installation of OpenX on Debian Lenny Linux and their solutions

Tuesday, June 22nd, 2010

If you’re installing openx on a Debian Linux, you will most probably be forced to note/change few things before the openx installation launches correctly:

Here are a list of things to check and assure are properly configured before you procceed1. If you use the disable_functions, it’s recommended to comment it out during the openx installation:
#disable_functions =exec,passthru,shell_exec,system,
proc_open,popen,curl_exec,curl_multi_exec,parse_ini_file,show_source

2. Increase memory_limit to at least 128MB this is a minimum requirement for openx to run properly:
Edit your /etc/php5/apache2/php.ini and set memory_limit to:
memory_limit = 192M

3. Set the date.timezone in your /etc/php.ini

You need to properly set the date.timezone function in Apache’s php.ini othewise the OpenX installation will refuse to continue with a warning:

timezoneOpenX has detected that your PHP installation is returning ‘System/Localtime’ as the timezone of your server. This is because of a patch to PHP applied by some Linux distributions. Unfortunately, this is not a valid PHP timezone. Please edit your php.ini file and set the ‘date.timezone’ property to the correct value for your server.

It took me a while until I found the proper way to set the date.timezone php variable, below is a correct way to set the date.timezone in php.ini:

echo 'date.timezone = Europe/London' >> /etc/php5/apache2/php.ini

Note that many people has provided a misinformation concerning the setup of date.timezone on php version 5.2 or 5.3.
Many posts online claim that the date.timezone should be set with date.timezone = “Europe/London” having the quotation marks is variable syntax error so if you enter it that way in your php.ini the date.timezone variable won’t be set correctly.
Some people on the net has also suggested that date.timezone variable format is in the form date.timezone = “US/Central” which I suspect is again erroneous.

Actually the Openx system requirements has a nice explanation on how to properly set the date.timezone in order to fix any emerging issues with the OpenX install, so I suggest you take 5 minutes time and read thoroughly before you start with the OpenX installation.

Howto install GeoTrust RapidSSL certificate on Debian Lenny / Squeeze / Wheezy Linux

Thursday, March 25th, 2010

I faced the task of generating official Validated SSL Certificates by in mydaily duties as a System Administrator at cadiaholding.com . Though generating self-signedSSL certificate is comparatively easy task. It was a pain in the ass setting Apache version 2.2.9-10+lenny6to correctly serve pages through https:// protocol over openssl version 0.9.8g-15+lenny6.I’ll try to go through the whole process of Generating the certificate in order to help some other Debianusers out there to face less setbacks in such a simple task as installing a Trusted SSL Certificate issued(bought) by RapidSSL. Even though this article will mostly deal with SSL certificate issued by RapidSSL,it should be not a problem to apply this methodogy with Verisign or some of the other Geotrust issuedSecure Socket Layer certificates.

In generating the Validated certficate I used enom which is a domain name,ssl certificates, email and hosting company whole-saler.
Fron emon’s website after logging in and using the web interface, there are two major things required to fill inin order to issue your Trusted SSL certificate.

1. Fill in in a form a CSR file, this is usually generated on the Linux server using the openssl.
To issue the CSR file required by Enom use the following commands:

a. First we generate an DES3 RSA encrypted key which we will use next to generate the opeensl CSR file required by ENOM.
debian:~# /usr/bin/openssl genrsa -des3 -out www.domain.com.key 2048
Enter pass phrase for www.domain.com.key:

You’ll be required to fill in a pass-phrase that will be later be required to fill in before Apache servers starts or restarts,so make sure you fill something you either remember or you keep the password stored in a file.
You have to change also the www.domain.com.key in accordance with your domain name.
Now as we already have a proper generated DES3 RSA key afterwards it’s necessery to generate the CSR file with the openssl command line frontend.
So here is how:

debian:~# /usr/bin/openssl req -new -key /home/hipo/www.domain.com.key -out /home/hipo/www.domain.com.csr

Again in the above example change all the paths and file names as you wish.
It’s necessery that the end user fill in a number of questions related to the Certificate Signing Request.
Herein I’ll list what kind of prompts will emerge after executing the above command:

Enter pass phrase for /home/hipo/www.domain.com.key:
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (eg, YOUR name) []:
Email Address []:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Note that you’ll hav eto fill in the pass phrase previously entered during the generation of the www.domain.com.key file.
In case if you’d like to read more thoroughly on the subject of howto create a Certificate Signing Request or (CSR) as we called it on multiple times, you can read About Certificate Signing Request (CSR) Generation Instructions – Apache SSL more in depth here

2. Hopefully following the above instructions you’ll now have a file named www.domain.csrJust open the www.domain.scr and copy paste it’s content to the ENOM website CSR * webform.

3. Further on select your Webserver type on Enom’s website:In our case we have to select Apache + ApacheSSL

4. What follows next is filling in your company contact information This is also required for proper certificate generation, you have to think twice before you fill in this data, take a note this can’t be changed later on without issuing a brand SSL new certificate.

Apart from the 3 major above requirements to fill in Enom there are some few more radio buttons to use to make some selections according to your personal preferences, however I won’t take time to dig in that and I’ll leave this to you.
After all the above is fulfilled you’ll have to submit your certificate details and choose an email address to which you will receive in a minute a RapidSSL Certificate Request Confirmation

Following a link from the email, will show you some basic information about the certificate about to be generated. That’s your final chance to cancel the issued Trusted Certificated.
If you’re absolutely sure the information about to enter the certificate is correct then you’ll have to follow a link and approve the certificate.

You’ll be informed that you’ll receive your certificate either through Certifier website (e.g. Enom’s website) or via another email.
I thought it’s more probable I receive it via email but anyways I was wrong. More thank 4 hours has passed since the certificate was issued and is available via Enom’s interface but I haven’t received nothing on my mail.
Therefore my friendly advice is to check about your brand new shiny Trusted Certificate on Emom’s website. I had mine ready in about 10 minutes after the CSR was issued.

Assuming that you’ve succesfully obtained the SSL Trusted certificate from RapidSSL what follows is setting up the certificate.
Initially I tried using documentation from RapidSSL website called Installing your SSL Certificate / Web Server Certificate / Secure Server Certificate from RapidSSL.com
I tried to configure one of my Virtualhost as shown in their example inserting in my /etc/apache/sites-available/www.domain.com file, few directives within the VirtualHost something like the shown below

SSLEngine on
# domain.com.crt cointains the Trusted SSL certificate generated and obtained by you from RapidSSL
SSLCertificateFile /etc/apache2/ssl/www.domain.com.crt
# www.domain.com.key contains the file used to generate the CSR file as described earlier in this post
SSLCertificateKeyFile /etc/apache2/ssl/www.domain.com.key

It is also possible insetad of using the SSLCertificateFile and SSLCertificateKeyFile directvies directives in Apache config to use:

 

Another alternative is to use

SSLCertificateFile /etc/ssl/certs/your-domain-name.crt
SSLCertificateKeyFile /etc/ssl/certs/your-domain-name.key
SSLCACertificateFile /etc/ssl/certs/gd_bundle.crt

The key file is the one generated earlier on the server and handed to the SSL regisrar, the files:

your-domain-name.crt and gd_bundle.crt files are provided by RapidSSL or from whatever SSL registrater the SSL was purchased.

After trying the above configuration and restarting apache with:

/etc/init.d/apache2 restart

Apache failed to start, it might be helpful to somebody out there the error I had in my apache error.log:
The error.log red the following:

[warn] RSA server certificate is a CA certificate (BasicConstraints: CA == TRUE !?)

After some 30 minutes or an hour of Googling on the error I came to the conclusion that the error is caused, becauseApache is supposed to work with .PEM files instead of the classical .CRT and .KEY files asnormally approached in most of the other Unix operating systems.

It took me a bit more of reading on the internet to find out that actually the .pem files so widely adopted in Debian simply contain both the www.domain.com.key file and the www.domain.com.crt key simply pasted one after another, this I also observed from the default Apache self-signed certificate that I believe comes with debian /etc/apache2/ssl/apache.pem .
So I copied both the content of my www.domain.com.key and www.domain.com.crt and store it in one file:
/etc/apache2/ssl/www.domain.com.pem

Also the following configuration:
SSLEngine on
SSLCertificateFile /etc/apache2/ssl/www.domain.com.pem

had to go in your
/etc/apache2/sites-enabled/www.domain.com

Last thing that’s left is to restart your Apache;

/etc/init.d/apache2 restart

Apache will prompt you for your certificate password entered by you during the www.domain.com.key generation. Type your password and with a bit of luck and hopefully with God’s help you’ll be having a Trusted Certificate on your webserver.

Last step is to check if the certificate is okay accessing your domain https://www.domain.com.

Well this is the end of the article, hope you enjoy.If you do please leave your comments, any corrections are also welcomed 🙂

Howto install FuzzyOcr on Debian 5.0 (Lenny) / FuzzyOCR install tutorial on Debian Linux

Friday, March 5th, 2010

FuzzyOcr Logo
Recently, I had a task to install FuzzyOCR on Debian Lenny in order to reduce the amount of the “image spam” delivered to the end users.Since there is no official install tutorial for debian users I decided to create this one with the hope it might be useful for others.
Here are few lines that explain what is FuzzyOCR;

FuzzyOcr is a plugin for SpamAssassin which is aimed at unsolicited bulk mail (also known as “Spam”) containing images as the main content carrier. Using different methods, it analyzes the content and properties of images to distinguish between normal mails (Ham) and spam mails.

Now I won’t get into details anymore and I’ll get you to the concrete packages and configurations I’ve done in order to have the software up and running.

1. Install required debian packages

debian-server# apt-get install netpbm gocr giftext giflib-tools libungif-bin
libpng3 libungif4g gifsicle ocrad
libstring-approx-perl libmldbm-perl libmldbm-sync-perl
liblog-agent-perl libpng12-dev libtiff4-dev libsvga1-dev libx11-dev

2. Download latest version of FuzzyOCR


debian-server# wget http://users.own-hero.net/~decoder/fuzzyocr/fuzzyocr-3.6.0.tar.gz

3. Copy some FuzzyOCR configuration and installation files in /etc/mail/spamassassin/

debian-server# cp -rpf FuzzyOcr.scansets /etc/mail/spamassassin/
debian-server# cp -rpf FuzzyOcr.preps /etc/mail/spamassassin/
debian-server# cp -rpf FuzzyOcr.pm /etc/mail/spamassassin/
debian-server# cp -rpf FuzzyOcr/ /etc/mail/spamassassin/
debian-server# cp -rpf FuzzyOcr.cf /etc/mail/spamassassin

4. Create some log files and files in order to use FuzzyOCR with a hashing database.

debian-server# touch /var/log/qmail/FuzzyOcr.log
debian-server# chown vpopmail:vchkpw /var/log/qmail/FuzzyOcr.log
debian-server# touch /etc/mail/spamassassin/FuzzyOcr.db
debian-server# chown vpopmail:vchkpw /etc/mail/spamassassin/FuzzyOcr.db
debian-server# touch /etc/mail/spamassassin/FuzzyOcr.safe.db
debian-server# chown vpopmail:vchkpw /etc/mail/spamassassin/FuzzyOcr.safe.db

5. Edit FuzzyOcr configuration files.

debian-server# vim /etc/mail/spamassassin/FuzzyOcr.cf

You need to put there the following directives:

focr_enable_image_hashing 2
focr_db_hash /etc/mail/spamassassin/FuzzyOcr.db
focr_db_safe /etc/mail/spamassassin/FuzzyOcr.safe.db
focr_db_max_days 15

Now there are few more things that need to be done before we have a complete install, e.g. we need to compile netpbm from source, because three of the binary executables required by FuzzyOcr are for some reason not bundled with debian lenny netpbm package. So;
So first we download and untar the latest version of netpbm:

debian-server# links "http://downloads.sourceforge.net/project/netpbm/super_stable/10.35.73/netpbm-10.35.73.tgz?use_mirror=sunet"
debian-server# tar -zxvvf netpbm-10.35.73.gz

We need to have the following “hack” in order to have the source compile properly:

debian-server# mkdir /usr/X11R6/lib
debian-server# ln -sf /usr/lib/libX11.so /usr/X11R6/lib/libX11.so

Next we compile the source of netbpm and install it:


debian-server# cd netpbm-10.35.73
debian-server# make && make install

If it happens that your build fails during the “make”, then you must use the apt-file program to determine which debian package contains the missing header files because of which the build has failed
We proceed next, with the installation of tesseract . Tesseract is 1 of the best OCR open source engine available nowadays
Therefore we now download and install it:

debian-server# wget http://tesseract-ocr.googlecode.com/files/tesseract-2.04.tar.gz
debian-server# tar -zxvvf tesseract-2.04.tar.gz
debian-server# cd tesseract-2.04
debian-server# ./configure && make && make install

In order to load FuzzyOcr in spamassassin we have to restart Spamassassin:

debian-server# /etc/init.d/spamassassin restart

Note: If you are have spamassassin running via djb daemontools restart spamassassin via the svc command:

Last thing we do is the check out if FuzzyOcr is correctly loaded and checking against image spam when new messages arrives, so here is how:

Change back to your FuzzyOcr-3.6.0/ directory:

debian-server# cd FuzzyOcr-3.6.0/
debian-server# cd samples
debian-server# spamassassin --debug FuzzyOcr < ocr-animated.eml >/dev/null

Check out the lines related to FuzzyOcr, you should have some lines in the output reporting FuzzyOcr has found a spam in the ocr-animated.eml file.
Another possible approach to test what is happening in spamassassin is to use:


debian-server# spamassassin -D

The above command will provide you with information about spamassassin in real time.
This article is pretty much in a beta stage, I’ll be glad of any feedback on it so I can advance it!
Thanks for reading!

Install Apache2 with SSL support on Debian Lenny Linux / (Quick way to generate Self Signed SSL certificate)

Thursday, February 25th, 2010

1. Install apache2 on your Debian Lenny

server# apt-get install apache2

2. Install openssl and it’s corequirements

server# apt-get install openssl ssl-cert

In case if you need php support as well on your Lenny:
server# apt-get install libapache2-mod-php5

3. Generate Self Signed SSL certificate

server# openssl req $@ -new -x509 -days 365 -nodes -out /etc/apache2/apache.pem -keyout /etc/apache2/apache.pem
You might consider changing the /etc/apache2/apache.pem to whatever you like your ssl certificate file to be called.
Now you must ensure yourself that the newly generated ssl certificate has proper permissions issue the command.

server# chmod 600 /etc/apache2/apache.pemThe default behaviour of the Apache server is to server unencrypted HTTP traffic on port 80, however in our case we need to enable SSL connections and therefore configure apache to serve and listen for traffic on port 443.

Therefore, we need to have Listen 443 in our /etc/apache2/ports.conf another thing we should do is to enable the ssl module with command:

server# a2enmod ssl

That should be it, now we have to restart the Apache webserver:

server# /etc/init.d/apache2 restart

To enable SSL on virtualhosts it’s required to change NameVirtualHost * in /etc/apache2/sites-available/default file
to:
NameVirtualHost *:80
NameVirtualHost *:443

To use SSL encryption on a specific Virtualhost, all you need to do is:
include:

SSLEngine on
SSLCertificateFile /etc/apache2/apache.pem

Installing SuPHP on Debian Lenny 5.04 with Apache 2.2.9

Thursday, February 18th, 2010

My daily duties as a sys admin today included installation and configuration of SuPHP .
SuPHP is an apache dynamic module for executing PHP scripts with the permissions of their owners. It consists basicly of twoparts Apache module (mod_suphp) and a setuid root binary (suphp). The suphp module is invoked by the mod_suphp module and instructsApache to change the user id (uid) of the process executing the PHP script.
SuPHP is not a standard Apache module so it’s not 100% tested. Therefore from security point of view it’s better not to use SuPHP.
So beware use it at your own risk! You better know what you’re doing if you’re installing this piece of soft.

The official SuPHP documentation is rather I would say archaic and it’s completely out of date. Though according to the official documentation it’s noted that suphp module won’t work with Apache 2.2.x, it actually works perfectly fine.
I’ve checked and I couldn’t find any tutorials on installing suphp on Debian Lenny therefore I decided to write this tutorial to shed some light on it.
So enough talk let’s approach to the installation and configuration of suphp;

1. Install the module itself from the debian package

debian-server# apt-get install libapache2-mod-suphp
Debian will enable the mod_suphp automatically after installation, though this kind of behaviour is pretty stupid, since it won’t disable mod_php5 which is enabled by default.

2 Therefore we need to disable mod_php5 from executing to enable suphp.

debian-server# a2dismod php5

3. Enable suphp globally for the Apache
Edit /etc/apache2/apache2.conf and put in the end of the configuration file

# Enable SuPHP
suPHP_Engine on
suPHP_AddHandler application/x-httpd-php .php

In my case I’m not using Debian’s default DocumentRoot website location for both my Apache and my VirtualHosts, therefore I need also to configure
suphp.conf

4. Edit /etc/suphp/suphp.conf and change;

;Path all scripts have to be in
docroot=/var/www/

to let’s say:
;Path all scripts have to be in
docroot=/home/

5. Restart your Apache server

debian-server# /etc/init.d/apache2 restart

Now test if mod_suphp is working on your Apache. We will test it through a tiny php script;
Paste the script to let’s say suphp.php

<? system( "id" ); ?>

Now if suphp is working you’ll see something like:
uid=1002(myuser) gid=1002(myuser) groups=1002(myuser)
instead of the default;
uid=33(www-data) gid=33(www-data) groups=32(www-data)

Now there are a few more drawbacks with SuPHP which I feel obliged to discuss.
On the first place suphp will excecute through php5-cgi and therefore the script execution
should be considered a way slower comparing to the default mod_php5.
I cannot precisely tell how much slower would be php script execution compared to mod_php5 but I
pressume at least 10 to 20% of the usual performance will be gone.
One of the possible ways to speed-up php execution in that case is to use mod_fastcgi.

Quick way to install mod_qos on Debian Lenny to protect from Slowloris

Thursday, February 18th, 2010

I’m gonna do a fast walk through on installing and enabling mod_qos on Debian, original article is available in Bulgarian on mpetrov’s blog .
So let’s go…
1. Install required development files and tools to be able to proper compile:

debian-server# apt-get install apache2-threaded-dev gcc

2. Download the mod_qos latest archive from sourceforge

debian-server# cd /usr/local/srcdebian-server# wget http://freefr.dl.sourceforge.net/project/mod-qos/mod-qos/9.7/mod_qos-9.8.tar.gz

3. Unarchive (Untar) the mod_qos archive and compile the module

debian-server# tar zxvf mod_qos-9.8.tar.gz
debian-server# cd mod_qos-9.8/apache2/
debian-server# apxs2 -i -c mod_qos.c

You can see from the compile output module is installed to; usr/lib/apache2/modules

4. Now let us create mod_qos configuration files

debian-server# cd /etc/apache2/mods-available/
debian-server# echo "LoadModule qos_module /usr/lib/apache2/modules/mod_qos.so" > qos.load

debian-server# vim /etc/apache2/mods-available/qos.conf

## QoS module Settings
<IfModule mod_qos.c>
# handles connections from up to 100000 different IPs
QS_ClientEntries 100000
# will allow only 50 connections per IP
QS_SrvMaxConnPerIP 50
# maximum number of active TCP connections is limited to 256
MaxClients 256
# disables keep-alive when 70% of the TCP connections are occupied:
QS_SrvMaxConnClose 180
# minimum request/response speed (deny slow clients blocking the server,
# ie. slowloris keeping connections open without requesting anything):
QS_SrvMinDataRate 150 1200
# and limit request header and body (carefull, that limits uploads and post requests too):
# LimitRequestFields 30
# QS_LimitRequestBody 102400
</IfModule>

5. All left is to load the mod_qos module into Apache and restart the webserver

debian-server# a2enmod qos
debian-server# /etc/init.d/apache2 restart

Congratulations, Now slowloris and many other Apache DoS techniques won’t bother you anymore!

Solution to a problem with VirtualHosts on Debian Lenny (Default Virtualhost opening by default overwritting the rest of the configured VirtualHosts)

Wednesday, February 17th, 2010

Configuring some Virtualhosts on a Debian server I administrate has led me to a really shitty problem. The problem itself consisted in that nomatter what kind of the configured VirtualHosts on the server I try to access the default one or the first one listed among Virtualhosts gets accessed. Believe me such an Apache behaviour is a real pain in the ass! I went through the VirtualHosts configurations many without finding any fault in them, everything seemed perfectly fine there. I started doubting something might prevent VirtualHosts to be served by the Webserver. Therefore to check if VirtualHosts configurations are properly loadedI used the following command:

debian-server:~# /usr/sbin/apache2ctl -S

Guess what, All was perfectly fine there as well. The command returned, my webserver configured VirtualHosts as enabled (linked) in: /etc/apache2/sites-enabled I took some time to ask in irc.freenode.net #debian channel if somebody has encountered the same weirdness, but unfortunately noobody could help there. I thinked over and over the problem and I started experimenting with various stuff in configurations until I got the problem.

The issue with non-working Virtualhosts in Debian lenny was caused by;
wrong NameVirtualHost *:80 directive
It’s really odd because enabling the directive as NameVirtualHost *:80 would report a warning just like there are more than one NameVirtualHost variable in configuration, on the other hand completely removing it won’t report any warnings during Apache start/restart but same time VirtualHosts would still be non-working.

So to fix the whole mess-up with VirtualHosts not working I had to modify in; my /etc/apache2/sites-enabled/000-default as follows;

NameVirtualHost *:80 changes toNameVirtualHost *

The rest of the Virtualhost stays the same;
This simple thing eradicated the f*cking issue which tortured me
for almost 3 hours! ghhh