Posts Tagged ‘php5’

Install and make Apache + PHP to work with PosgreSQL database server on Debian Linux and set up server Web Posgre interface Pgpadmin howto

Wednesday, June 15th, 2016

make-apache-php-work-with-postgresql-pgsql-and-install-postgresql-db-web-admin-interface

In previous article I've wrote on how to install postgresql on Debian Linux using the deb repository this was necessery to import some PostGres DBs, however this was not enough to run the posgresql php based website aimed as connection from Apache / PHP module to PostGre was failing after a bit of investigation and a check in phpinfo(); I've realized the module PHP module for postgres pgsql.so was missing, here is what I did in order to install it:
 

debian:~# apt-get install php5-pgsql phppgadmin libapache2-mod-auth-pgsql 

PHP sessions enable configuration

As it is common a common problem with PHP applications written to use PostGres is to loose sessions and by default PHP does not have configured sessions.save_path it is a very good practice to directly enable it in /etc/php5/apache2/php.ini open the file in text editor:
 

debian:~# vim /etc/php5/apache2/php.ini


Find the commented directive line:
 

;session.save_path = “/tmp”


and uncomment it, i.e.:
 

session.save_path = “/tmp”


Quit saving vim with the usual :wq!

The 3 modules provides pgsql.so for PHP and mod_auth_pgsql.so for Apache2, the 3rd packae phpgadmin provides a Web administration interface for installed PostgreSQL servers Databases, for those experienced with MySQL Database its the same as PHPMyAdmin.

 

 Here is quick configuration for use of PostgreAdmin interface:

By default PHPPGADMIN installation process configure the Apache2 server' /etc/phppgadmin/apache.conf  to use  /etc/apache2/conf.d/phppgadmin


Here is the default my server package instaleld  file content:

 

Alias /phppgadmin /usr/share/phppgadmin

<Directory /usr/share/phppgadmin>

DirectoryIndex index.php
AllowOverride None

order deny,allow
deny from all
allow from 127.0.0.0/255.0.0.0 ::1/128
# allow from all

<IfModule mod_php5.c>
  php_flag magic_quotes_gpc Off
  php_flag track_vars On
  #php_value include_path .
</IfModule>
<IfModule !mod_php5.c>
  <IfModule mod_actions.c>
    <IfModule mod_cgi.c>
      AddType application/x-httpd-php .php
      Action application/x-httpd-php /cgi-bin/php
    </IfModule>
    <IfModule mod_cgid.c>
      AddType application/x-httpd-php .php
      Action application/x-httpd-php /cgi-bin/php
    </IfModule>
  </IfModule>
</IfModule>

</Directory>

It is generally a good practice to change the default Alias location of phppgadmin, so edit the file and change it to something like:
 

Alias /phppostgresgadmin /usr/share/phppgadmin

 

  • Then phpPgAdmin is available at http://servername.com/phppostgresadmin (only from localhost, however in my case I wanted to be able to access it also from other hosts so allowed PostgresGadmin from every hosts, to do so, I've commented in above config

 

# allow from 127.0.0.0/255.0.0.0 ::1/128

 

and uncommented #allow from all line, e.g.:
 

allow from all


Also another thing here is in your VirtualHost whenever you plan to access the PHPPGADMIN is to include in config ( in my case this is the file /etc/apache2/sites-enabled/000-default before (</VirtualHost> end line) following Alias:
 

Alias /phpposgreadmin /usr/share/phppgadmin


Then to access PostGreSQL PHP Admin interface in Firefox / Chrome open URL:

 

http://your-default-domain.com/phpposgreadmin

phpPgAdmin-postgresql-php-web-interface-debian-linux-screenshot
 

 

Configure access to a remote PostgreSQL Server

With PhpPgAdmin, you can manage many PostgreSQL servers locally (on the localhost) or on remote hosts.

First, you have to make sure that the distant PostgreSQL server can handle your request, that you can connect to it. You can do this by modifying the /etc/postgresql/9.5/main/filepg_hba.conf and adding a line like:

# PhpPgAdmin server access host all db_admin xx.xx.xx.xx 255.255.255.255 md5

Then, you need to add your distant PostgreSQL server into the config file for PhpPgAdmin. This file is  /etc/phppgadmin/config.inc.php the default postgresql port is 5432, however you might have configured it already to use some different port if you're not sure about the port number the postgresql is listening check it out:

 

debian:~# grep -i port /etc/postgresql/*/main/postgresql.conf
etc/postgresql/9.5/main/postgresql.conf:port = 5433                # (change requires restart)
/etc/postgresql/9.5/main/postgresql.conf:                    # supported by the operating system:
/etc/postgresql/9.5/main/postgresql.conf:                    # supported by the operating system:
/etc/postgresql/9.5/main/postgresql.conf:# ERROR REPORTING AND LOGGING


To login to phppgadmin interface there is no root administrator user such as in PHP so you will need to priorly create some user and later use it for connection from Postgres Web interface.

To create from console new user in postgres:
 

debian:~# su – postgres
posgres@debian:~$ psql template1
posgres@debian:~$ psql -d template1 -U postgres

 

Welcome to psql 9.5, the PostgreSQL interactive terminal. Type: \copyright for distribution terms \h for help with SQL commands \? for help on internal slash commands \g or terminate with semicolon to execute query \q to quit template1=#

template1=# CREATE USER MyNewUser WITH PASSWORD 'myPassword';


To add a new database to postgres from shell:

template1=# CREATE DATABASE NewDatabase;
 

template1=# GRANT ALL PRIVILEGES ON DATABASE NewDatabase to MyNewUser;

 

template1=# q

Last command instructs it to quit if you want to get more info about possible commands do type instead of q ? for general help or for database / table commands only h
If you need to connect to NewDatabase just to test first it works in console before trying it from postgrepgadmin

 

 

 

 

 

posgres@debian:~$ psql -d NewDatabase -U MyNewUser

 

 

 

 

Howto install XCache Debian on GNU / Linux to accelerate Apache Webserver – XCache Best alternative to outdated PHP cacher EAccelerator

Thursday, February 26th, 2015

xcache_install-and-enable-best-alternative-php-cacher-to-eaccelerator-logo
I was using Eaccelerator until recently on all Apache / PHP / MySQL  (LAMP) web-servers as a caching engine (Webserver accelerator) across all Debian GNU / Linux Lenny / Squeeze / Etch servers.
However recently, I've noticed in phpinfo output on some of the Debian hosts, that eaccelerator was loaded but showed:

 Caching Enabled false

eaccelerator_caching_enabled_false-phpinfo-screenshot-apache-debian-linux.

 

Our servers are quite busy serving about 50 000 to 100 000 requests and thus not having enabled caching puts a lot of extra load on the CPU and eats a lot of memory which were usually saved by eAccelerator.
Logically I tried fixing the issues following some Stackoverflow threads recommendations such as this one but didn't work I tried playing manually spending hours trying to make eaccelerator run again and as a final mean, I even tried to upgrade eaccelerator to newer version but noticed the latest available eaccelerator version 0.9.6 was 2.5 years old (from 03.09.2012). Thus while there is no new release, just make s so just to make sure I didn't break the module with (default Debian bundled distribution package which is also installed on the servers)  re-installed eAccelerator from source 

This didn't worked either and since I was totally pissed off by the worsened systems performance (CPU load increased with to 10-30%) per server, I looked for some alternatives I can use and in the mean time I learned a bit more about history of PHP Accelerators, I learned some interesting things such as that  ionCube (PHPA) was the  first PHP Accelerator Apache like module (encoding PHP code),  created in 2001, later it become inspirational for  birth to PHP-APC (Alternative PHP Cache) Apache module. 
There is also Zend Opcache PHP accelerator (available since PHP 5.5 onwards)  but since Zend OpCache caches well PHP Zend written PHP code and servers run PHP 5.4 + sites are not using Zend PHP Framewosk  this was an option.
Further investigation lead me to MMCache which is already too obsolete (latest release is from 2013), PHPExpress – PHP Encoder which  was said to run on Windows, Linux, FreeBSD, NetBSD, Mac OS X, and Solaris) but already looks dead as there were no new releases since January 2012) and finally Lighttpd's XCache.

To give you an idea on what exactly is the difference between Apache Webserver with PHP-APC Caching or other PHP Cacher enabled and the Standard way PHP Interprets PHP scripts below is a diagram:

php-apc-cache-how-php-caching-works-with-and-without-encoding-php-code-diagram

Obviously my short research shows that from all the available PHP Cache Encoder / Accelerators only ones that seemed to be recently updated (under active development) are APC and XCache.
I've already used PHP-APC earlier on some servers and was having having some random Apache Webservers crashes and weird empty pages with some PHP pages and besides that APC is known to give lower speed in PHP caching than Eaccelerator and XCache, leaving me with the only and logical choise to use XCACHE.

Here is how Xcache developers describe their opcacher:
 

XCache is a free, open source operation code cacher, it is designed to enhance the performance of PHP scripts execution on servers. It optimizes the performance by eliminating the compilation time of PHP code by caching the compiled version of code into the memory and this way the compiled version loads the PHP script directly from the memory. This will surety accelerate the page generation time by up to 5 times faster and also optimizes and increases many other aspects of php scripts and reduce website/server load.

 


Thanksfully XCache is shipped by default with all Debians (Etch /Lenny / Squeeze / Wheezy)  Linuces so to install it just run the standard apt cmd:
 

apt-get install –yes php5-xcache


Then to enable XCache all I had to do is edit /etc/php5/apache2/php.ini and place below code
 

debian-server:~# vim /etc/php5/apache2/php.ini

 

[xcache-common]
;; install as zend extension (recommended), normally "$extension_dir/xcache.so"
;;zend_extension = /usr/lib/php5/20100525/xcache.so

 

[xcache.admin]
xcache.admin.enable_auth = On
; Configure this to use admin pages
; xcache.admin.user = "mOo"
; xcache.admin.pass = md5($your_password)
; xcache.admin.pass = ""

[xcache]
; ini only settings, all the values here is default unless explained

; select low level shm/allocator scheme implemenation
xcache.shm_scheme =        "mmap"
; to disable: xcache.size=0
; to enable : xcache.size=64M etc (any size > 0) and your system mmap allows
xcache.size  =                16M
; set to cpu count (cat /proc/cpuinfo |grep -c processor)
xcache.count =                 1
; just a hash hints, you can always store count(items) > slots
xcache.slots =                8K
; ttl of the cache item, 0=forever
xcache.ttl   =                 0
; interval of gc scanning expired items, 0=no scan, other values is in seconds
xcache.gc_interval =           0
; same as aboves but for variable cache

Note that Debian location which instructs xcache to load in Apache as a module is xcache.ini – e.g. /usr/share/php5/xcache/xcache.ini, so instead of placing above configuration right into php.ini you might prefer to place it in xcache.ini (though I personally prefer php.ini) because it is easier for me to later control how PHP behaves from single location.

To test whether XCache is enabled for Apache Webserver:

Create phpinfo.php somewhere in DocumentRoot (in my case this was /var/www/php_info.php)

debian-server:~# vim /var/www/php_info.php

 

<php?
phpinfo()
?>


When you access the php_info.php in browser you will get XCache loaded as in below screenshot:

 

xcache_loaded-in-php-apache-phpinfo-output-debian-gnu-linux-server

To Test whether Xcache is enabled also for PHP CLI (applications set to run as a crontab – cronjob) :
 

debian-server:~# php -v
PHP 5.4.37-1~dotdeb.0 (cli) (built: Feb  2 2015 05:03:00)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2014 Zend Technologies
    with XCache v3.2.0, Copyright (c) 2005-2014, by mOo
    with XCache Cacher v3.2.0, Copyright (c) 2005-2014, by mOo

 

Once it is tested as successful install you might want to enable the XCache admin (which is disabled by default), to enable XCache Admin on Debian you need to generate new password for it first like so:

 

echo -n "xcache_rulez" | md5sum
acbf5ba4a44f03058aa0ad11e0a6b645

 


Then you need to add in /etc/php5/mods-available/xcache.ini

debian-server:~# vim /etc/php5/mods-available/xcache.ini
[xcache.admin]
xcache.admin.enable_auth = On
; Configure this to use admin pages
 xcache.admin.user = "admin"
; xcache.admin.pass = md5($your_password)
 xcache.admin.pass = "change_with_above_generated_password_here"

 

To enable admin and be able to access it in a browser (if you're using as a documentroot /var/www/ and docroot supports interpretting php scripts and (has AllowOverride All) enabled to also support htaccess authentication do:
 

debian-server:~# cd /var/www/
debian-server:~# ln -sf /usr/share/xcache/htdocs/ xcache

When you access http://your-url-address.com/xcache/ you should see in browser some statistics along with all configured xcache options:

xcacher-admin-on-debian-gnu-linux-in-chrome-browser-screenshot-enable-xcacher-admin-howto

If you have time you can play with the options and get some speed minor speed improvements. The overall increase in page opening XCache should give you is between 100% – 190% !

Enjoy 🙂

How to deb upgrade PHP 5.3.3-7 / MySQL Server 5.1 to PHP 5.4.37 MySQL 5.5 Server on Debian 6.0 / 7.0 Squeeze / Wheezy GNU / Linux

Thursday, February 12th, 2015

how-to-deb-upgrade-mysql-server-5.1-to-mysql-5.5-php-5.3-to-php-5.4-5.5-upgrade-howto-on-old-stable-debian-squeeze-wheezy

I've been still running Debian Squeeze 6.0 GNU / Linux on few of the Linux / Apache / MySQL servers I'm administrating and those servers are running few Wordperss / Joomla websites which lately face severe MySQL performance issues. I tried to optimize using various mysql performance optimization scripts such as mysql-tuner.pl, Tuning-primer.sh and Percona Toolkit – a collection of advanced command-line tools for system administrators and tech / support staff to perform a variety of MySQL and system tasks that are too difficult or complex to perform manually. Though with above tools and some my.cnf tunizations I managed to achieve positive performance improvement results with above optimizations, still I didn't like how MyQSL served queries and since the SQL server is already about 5 years old (running version 5.1) and the PHP on sever is still at 5.3 branch, I was advised by my dear colleague Anatoliy to try version update as a mean to improve SQLserver performance. I took seriously the suggestion to try upgrade as a mean to resolve performance issues in this article I will explain in short what I had to do to make MySQL upgrade a success

Of course to try keep deb installed software versions as fresh as possible possible deb packagse, I'm already using Debian Back Ports (for those who hear it a first time Debian Backports is a special repository for Stable versioned Debian Desktop and Servers  – supporting stable releases of Debian Linux) which allows you to keep install packages versions less outdated (than default installable software which usually are way behind latest stable package versions with 2-5 years).

If you happen to administer Stable Debian servers and you never used BackPorts I warmly recommend it as it often includes security patches of packages part of Debian stable releases that reached End Of Support (EOS) and already too old even for security updates to be issued by respective Debian Long Term Suport (LTS) repositories.

If you're like me and still in situation to manage remotely Debian 6.0 Squeeze and its the first time you hear about BackPorts and Debian LTShttps://wiki.debian.org/LTS/ to start using those two add to your /etc/apt/sources.list below 3 lines

Open with vim editor and press shift+G to go to last line of file and then press I to enter INSERT mode, once you're done to save, press (ESC) then press : and type x! in short key combination for exit and save setting in vim is 
 

Esc + :x! 

 

debian-server:~# vim /etc/apt/sources.list
deb http://http.debian.net/debian squeeze-lts main contrib non-free
deb-src http://http.debian.net/debian squeeze-lts main contrib non-free
deb http://http.debian.net/debian-backports squeeze-backports main

If you haven't been added a security updates line in /etc/apt/sources.list make sure you add also:

 

deb http://security.debian.org/ squeeze/updates main contrib non-free
deb-src http://security.debian.org/ squeeze/updates main contrib non-free


Then to apply latest security updates and packages from LTS / Backports repository run the usual:

 

debian-server:~# apt-get update && apt-get –yes upgrade
….

If you need to search a package or install something from just added backports repository use:

 

debian-server:~# apt-cache -t squeeze-backports search "mysql-server"
auth2db – Powerful and eye-candy IDS logger, log viewer and alert generator
torrentflux – web based, feature-rich BitTorrent download manager
cacti – Frontend to rrdtool for monitoring systems and services
mysql-server-5.1 – MySQL database server binaries and system database setup
mysql-server-core-5.1 – MySQL database server binaries
mysql-server – MySQL database server (metapackage depending on the latest version)

 

To install specific packages only with all their dependencies from Backports while keeping rest of packages from Debian Stable:

 

debian-server:~# apt-get install -t squeeze-backports "package_name"

In same way you can also search or install specific packages from LTS repo:

 

debian-server:~# apt-get search -t squeeze-lts "package_name"

debian-server:~# apt-get install -t squeeze-lts "package_name"

Latest mysql available from Debian BackPorts and LTS is still quite old 5.1.73-1+deb6u1 therefore I made an extensive research online on how can I easily update MySQL 5.1 to MySQL 5.5 / 5.6 on Debian Stable Linux.
 

Luckily there were already DotDeb deb repositories for Debian LAMP (Linux / Apache  / MySQL / PHP / Nginx ) running servers prepared in order to keep the essential Webserver services up2date even long after distro official support is over. I learned about existence of this repo thanks to a Ryan Tate's post who updates his LAMP stack on TurnKey Linux which by the way is based on slightly modified official stable Debian Linux releases packages

To start using DotDeb repos add in /etc/apt/sources.list (depending whereh you're on Squeeze or Wheeze Debian):

 

deb http://packages.dotdeb.org squeeze all
deb-src http://packages.dotdeb.org squeeze all

or for Debian Wheezy add repos:

 

deb http://packages.dotdeb.org wheezy all
deb-src http://packages.dotdeb.org wheezy all

 

I was updating my DebianLatest MySQL / PHP / Apache release to Latest ones on (6.0.4) Squeeze so added above squeeze repos:

Before refreshing list of package repositories, to authenticate repos issue:

 

debian-server:~# wget -q http://www.dotdeb.org/dotdeb.gpg
debian-server:~# apt-key add dotdeb.gpg

Once again to update my packages from newly added DodDeb repository

 

debian-server:~# apt-get update

Before running the SQL upgrade to insure myself, I dumped all databases with:

 

debian-server:~# mysqldump -u root -p -A > /root/dump.sql

Finally I was brave enough to run apt-get dist-upgrade to update with latest LAMP packages

 

debian-server:~# apt-get dist-upgrade
Reading package lists… Done
Building dependency tree
Reading state information… Done
Calculating upgrade… Done
The following packages will be REMOVED:
  mysql-client-5.1 mysql-server mysql-server-5.1
The following NEW packages will be installed:
  libaio1 libmysqlclient18 mysql-client-5.5 mysql-client-core-5.5 python-chardet python-debian
The following packages will be upgraded:
  curl krb5-multidev libapache2-mod-php5 libc-bin libc-dev-bin libc6 libc6-dev libc6-i386 libcurl3 libcurl3-gnutls libcurl4-openssl-dev libevent-1.4-2
  libgssapi-krb5-2 libgssrpc4 libjasper1 libk5crypto3 libkadm5clnt-mit7 libkadm5srv-mit7 libkdb5-4 libkrb5-3 libkrb5-dev libkrb53 libkrb5support0 libmysqlclient-dev
  libxml2 libxml2-dev locales mysql-client mysql-common ntp ntpdate php-pear php5 php5-cgi php5-cli php5-common php5-curl php5-dev php5-gd php5-imagick php5-mcrypt
  php5-mysql php5-odbc php5-recode php5-sybase php5-xmlrpc php5-xsl python-reportbug reportbug unzip

50 upgraded, 6 newly installed, 3 to remove and 0 not upgraded.
Need to get 51.7 MB of archives.
After this operation, 1,926 kB of additional disk space will be used.
Do you want to continue [Y/n]? Y

As you see from above output above command updates Apache webservers / PHP and PHP related modules, however it doesn't update MySQL installed version, to update also MySQL server 5.1 to MySQL server 5.5

 

debian-server:~#  apt-get install –yes mysql-server mysql-server-5.5

You will be prompted with the usual Debian ncurses text blue interface to set a root password to mysql server, just set it the same as it used to be on old upgraded MySQL 5.1 server.

Well now see whether mysql has properly restarted with ps auxwwf

 

debian-server:~#  ps axuwwf|grep -i sql
root     22971  0.0  0.0 112360   884 pts/11   S+   15:50   0:00  |                   \_ grep -i sql
root     19436  0.0  0.0 115464  1556 pts/1    S    12:53   0:00 /bin/sh /usr/bin/mysqld_safe
mysql    19837  4.0  2.3 728192 194552 pts/1   Sl   12:53   7:12  \_ /usr/sbin/mysqld –basedir=/usr –datadir=/var/lib/mysql –plugin-dir=/usr/lib/mysql/plugin –user=mysql –pid-file=/var/run/mysqld/mysqld.pid –socket=/var/run/mysqld/mysqld.sock –port=3306
root     19838  0.0  0.0 110112   700 pts/1    S    12:53   0:00  \_ logger -t mysqld -p daemon.error

In my case it was running, however if it fails to run try to debug what is going wrong on initialization by manually executing init script /etc/init.d/mysql stop; /etc/init.d/mysql start and look for errors. You can also manually try to run mysqld_safe from console if it is not running run:

 

debian-server:~# /usr/bin/mysqld_safe &

This should give you a good hint on why it is failing to run
 

One more thing left is to check whether php modules load correctly to do so issue:

 

debian-server:~# php -v
Failed loading /usr/lib/php5/20090626/xcache.so:  /usr/lib/php5/20090626/xcache.so: cannot open shared object file: No such file or directory

Failed loading /usr/lib/php5/20090626/xdebug.so:  /usr/lib/php5/20090626/xdebug.so: cannot open shared object file: No such file or directory


You will likely get an exception (error) like above.
To solve the error, reinstall xcache and xcache-debug debs

 

debian-server:~# apt-get purge php5-xcache php5-xdebug

Now PHP + MySQL + Apache environment should be running much smootly.

debian-squeeze-wheeze-update-install-mysql-sevver5.55-620x344-howto

Upgrading the MySQL server / PHP library to MySQL server 5.6 / PHP 5.5 on Wheeze Linux is done in very much analogous ways all you have to do is change the repositories with above wheeze 7.0 ones and to follow the process as described in this article. I haven't tested update on Wheezy yet, so if you happen to try my article with wheezy reports and got a positive upgrade result please drop a comment.

How to Turn Off, Suppress PHP Notices and Warnings – PHP error handling levels via php.ini and PHP source code

Friday, April 25th, 2014

php-logo-disable-warnings-and-notices-in-php-through-htaccess-php-ini-and-php-code

PHP Notices are common to occur after PHP version upgrades or where an obsolete PHP code is moved from Old version PHP to new version. This is common error in web software using Frameworks which have been abandoned by developers.

Having PHP Notices to appear on a webpage is pretty ugly and give a lot of information which might be used by malicious crackers to try to break your site thus it is always a good idea to disable PHP Notices. There are plenty of ways to disable PHP Notices

The easiest way to disable it is globally in all Webserver PHP library via php.ini (/etc/php.ini) open it and make sure display_errors is disabled:

display_errors = 0

or

display_errors = Off

Note that that some claim in PHP 5.3 setting display_errors to Off will not work as expected. Anyways to make sure where your loaded PHP Version display_errors is ON or OFF use phpinfo();

It is also possible to disable PHP Notices and error reporting straight from PHP code you need code like:

 

<?php
// Turn off all error reporting
error_reporting(0);
?>

 

or through code:

 

ini_set('display_errors',0);


PHP has different levels of error reporting, here is complete list of possible error handling variables:

 

 

 

<?php
// Report simple running errors

error_reporting(E_ERROR | E_WARNING | E_PARSE);

// Reporting E_NOTICE can be good too (to report uninitialized
// variables or catch variable name misspellings …)

error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);

// Report all errors except E_NOTICE
// This is the default value set in php.ini

error_reporting(E_ALL ^ E_NOTICE);
// Report all PHP errors (see changelog)

error_reporting(E_ALL);
// Report all PHP errors error_reporting(-1);
// Same as error_reporting(E_ALL);

ini_set('error_reporting', E_ALL); ?>

The level of logging could be tuned on Debian Linux via /etc/php5/apache2/php.ini or if necessary to set PHP log level in PHP CLI through /etc/php5/cli/php.ini with:

error_reporting = E_ALL & ~E_NOTICE

 

If you need to remove to remove exact warning or notices from PHP without changing the way  PHPLib behaves is to set @ infront of variable or function that is causing NOTICES or WARNING:
For example:
 

@yourFunctionHere();
@var = …;


Its also possible to Disable PHP Notices and Warnings using .htaccess file (useful in shared hosting where you don't have access to global php.ini), here is how:

# PHP error handling for development servers
php_flag display_startup_errors off
php_flag display_errors off
php_flag html_errors off
php_flag log_errors on
php_flag ignore_repeated_errors off
php_flag ignore_repeated_source off
php_flag report_memleaks on
php_flag track_errors on
php_value docref_root 0
php_value docref_ext 0
php_value error_log /home/path/public_html/domain/php_errors.log
php_value error_reporting -1
php_value log_errors_max_len 0

This way though PHP Notices and Warnings will be suppressed errors will get logged into php_error.log

Finding spam sending php scripts on multiple sites servers – Tracing and stopping spammer PHP scripts

Monday, April 14th, 2014

stop_php_mail-spam-find-spammer-and-stop-php-spammer-websites
Spam has become a severe issue for administrators, not only for mail server admins but also for webshosting adms. Even the most secure spam protected mail server can get affected by spam due to fact it is configured to relay mail from other servers acting as web hosting sites.

Webhosting companies almost always suffer seriously from spam issues and often their mail servers gets blocked (enter spam blacklists), because of their irresponsible clients uploading lets say old vulnerable Joomla, WordPress without Akismet or proper spam handling plugin,a CMS which is not frequently supported / updated or custom client insecure php code.

What I mean is Shared server A is often configured to sent mail via (mail) server B. And often some of the many websites / scripts hosted on server A gets hacked and a spam form is uploaded and tons of spam start being shipped via mail server B.

Of course on mail server level it is possible to configure delay between mail sent and adopt a couple of policies to reduce spam, but the spam protection issue can't be completely solved thus admin of such server is forced to periodically keep an eye on what mail is sent from hosting server to mail server.
 


If you happen to be one of those Linux (Unix) webhosting admins who find few thousand of spammer emails into mail server logs or your eMail server queue and you can't seem to find what is causing it, cause there are multiple websites shared hosting using mainly PHP + SQL and you can't identify what php script is spamming by reviewing  Apache log / PHP files. What you can do is get use of:

PHP mail.log directive

Precious tool in tracking spam issues is a PHP Mail.log parameter, mail log paramater is available since PHP version >= 5.3.0 and above.
PHP Mail.log parameter records all calls to the PHP mail() function including exact PHP headers, line numbers and path to script initiating mail sent.

Here is how it is used:
 

1. Create empty PHP Mail.log file

touch /var/log/phpmail.log

File has to be writtable to same user with which Apache is running in case of Apache with SuPHP running file has to be writtable by all users.

On Debian, Ubunut Linux:

chown www:data:www-data /var/log/phpmail.log

On CentOS, RHEL, SuSE phpmail.log has to be owned by httpd:

chown httpd:httpd /var/log/phpmail.log

On some other distros it might be chown nobody:nobody etc. depending on the user with which Apache server is running.

 

2. Add to php.ini configuration following lines

mail.add_x_header = On
mail.log = /var/log/phpmail.log

PHP directive instructs PHP to log complete outbund Mail header sent by mail() function, containing the UID of the web server or PHP process and the name of the script that sent the email;
 

(X-PHP-Originating-Script: 33:mailer.php)


i.e. it will make php start logging to phpmail.log stuff like:
 

 

mail() on [/var/www/pomoriemonasteryorg/components/com_xmap/2ktdz2.php:1]: To: info@globalremarketing.com.au — Headers: From: "Priority Mail" <status_93@pomoriemon
astery.org> X-Mailer: MailMagic2.0 Reply-To: "Priority Mail" <status_93@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: multipart/alternative;boundary="——
—-13972215105347E886BADB5"
mail() on [/var/www/pomoriemonasteryorg/components/com_xmap/2ktdz2.php:1]: To: demil7167@yahoo.com — Headers: From: "One Day Shipping" <status_44@pomoriemonastery.
org> X-Mailer: CSMTPConnectionv1.3 Reply-To: "One Day Shipping" <status_44@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: multipart/alternative;boundary="—
——-13972215105347E886BD344"
mail() on [/var/www/pomoriemonasteryorg/components/com_xmap/2ktdz2.php:1]: To: domainmanager@nadenranshepovser.biz — Headers: From: "Logistics Services" <customer.
id86@pomoriemonastery.org> X-Mailer: TheBat!(v3.99.27)UNREG Reply-To: "Logistics Services" <customer.id86@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: mult
ipart/alternative;boundary="———-13972215105347E886BF43E"
mail() on [/var/www/pomoriemonasteryorg/components/com_xmap/2ktdz2.php:1]: To: bluesapphire89@yahoo.com — Headers: From: "Priority Mail" <status_73@pomoriemonaster
y.org> X-Mailer: FastMailer/Webmail(versionSM/1.2.6) Reply-To: "Priority Mail" <status_73@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: multipart/alternativ
e;boundary="———-13972215105347E886C13F2"

 

On Debian / Ubuntu Linux to enable this logging, exec:

echo 'mail.add_x_header = On' >> /etc/php5/apache2/php.ini
echo 'mail.log = /var/log/phpmail.log' >> /etc/php5/apache2/php.ini


I find it useful to symlink /etc/php5/apache2/php.ini to /etc/php.ini its much easier to remember php location plus it is a standard location for many RPM based distros.

ln -sf /etc/php5/apache2/php.ini /etc/php.ini

Or another "Debian recommended way" to enable mail.add_x_header logging on Debian is via:

echo 'mail.add_x_header = On' >> /etc/php5/conf.d/mail.ini
echo 'mail.log = /var/log/phpmail.log' >> /etc/php5/conf.d/mail.ini

On Redhats (RHEL, CentOS, SuSE) Linux issue:

echo 'mail.add_x_header = On' >> /etc/php.ini
echo 'mail.log = /var/log/phpmail.log' >> /etc/php.ini

3. Restart Apache

On Debian / Ubuntu based linuces:

/etc/init.d/apache2 restart

P.S. Normally to restart Apache without interrupting client connections graceful option can be used, i.e. instead of restarting do:

/etc/init.d/apache2 graceful

On RPM baed CentOS, Fedora etc.:

/sbin/service httpd restart

or

apachectl graceful
 

4. Reading the log

To review in real time exact PHP scripts sending tons of spam tail it:

tail -f /var/log/phpmail.log

 

mail() on [/var/www/remote-admin/wp-includes/class-phpmailer.php:489]: To: theosfp813@hotmail.com — Headers: Date: Mon, 14 Apr 2014 03:27:23 +0000 Return-Path: wordpress@remotesystemadministration.com From: WordPress Message-ID: X-Priority: 3 X-Mailer: PHPMailer (phpmailer.sourceforge.net) [version 2.0.4] MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="UTF-8"
mail() on [/var/www/pomoriemonasteryorg/media/rsinstall_4de38d919da01/admin/js/tiny_mce/plugins/inlinepopups/skins/.3a1a1c.php:1]: To: 2070ccrabb@kiakom.net — Headers: From: "Manager Elijah Castillo" <elijah_castillo32@pomoriemonastery.org> X-Mailer: Mozilla/5.0 (Windows; U; Windows NT 5.0; es-ES; rv:1.9.1.7) Gecko/20100111 Thunderbird/3.0.1 Reply-To: "Manager Elijah Castillo" <elijah_castillo32@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: multipart/alternative;boundary="———-1397463670534B9A76017CC"
mail() on [/var/www/pomoriemonasteryorg/media/rsinstall_4de38d919da01/admin/js/tiny_mce/plugins/inlinepopups/skins/.3a1a1c.php:1]: To: 20wmwebinfo@schools.bedfordshire.gov.uk — Headers: From: "Manager Justin Murphy" <justin_murphy16@pomoriemonastery.org> X-Mailer: Opera Mail/10.62 (Win32) Reply-To: "Manager Justin Murphy" <justin_murphy16@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: multipart/alternative;boundary="———-1397463670534B9A7603ED6"
mail() on [/var/www/pomoriemonasteryorg/media/rsinstall_4de38d919da01/admin/js/tiny_mce/plugins/inlinepopups/skins/.3a1a1c.php:1]: To: tynyrilak@yahoo.com — Headers: From: "Manager Elijah Castillo" <elijah_castillo83@pomoriemonastery.org> X-Mailer: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; pl; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 Reply-To: "Manager Elijah Castillo" <elijah_castillo83@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: multipart/alternative;boundary="———-1397463670534B9A7606308"
mail() on [/var/www/pomoriemonasteryorg/media/rsinstall_4de38d919da01/admin/js/tiny_mce/plugins/inlinepopups/skins/.3a1a1c.php:1]: To: 2112macdo1@armymail.mod.uk — Headers: From: "Manager Justin Murphy" <justin_murphy41@pomoriemonastery.org> X-Mailer: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; pl; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 Reply-To: "Manager Justin Murphy" <justin_murphy41@pomoriemonastery.org> Mime-Version: 1.0 Content-Type: multipart/alternative;boundary="———-1397463670534B9A76086D1"

 

As you can see there is a junky spam mails sent via some spammer script uploaded under name .3a1a1c.php, so to stop the dirty bastard, deleted the script:

rm -f /var/www/pomoriemonasteryorg/media/rsinstall_4de38d919da01/admin/js/tiny_mce/plugins/inlinepopups/skins/.3a1a1c.php

It is generally useful to also check (search) for all hidden .php files inside directoring storing multiple virtualhost websites, as often a weirdly named hidden .php is sure indicator of either a PHP Shell script kiddie tool or a spammer form.

Here is how to Find all Hidden Perl / PHP scripts inside /var/www:

find . -iname '.*.php'
./blog/wp-content/plugins/fckeditor-for-wordpress-plugin/ckeditor/plugins/selection/.0b1910.php
./blog/wp-content/plugins/fckeditor-for-wordpress-plugin/filemanager/browser/default/.497a0c.php
./blog/wp-content/plugins/__MACOSX/feedburner_feedsmith_plugin_2.3/._FeedBurner_FeedSmith_Plugin.php

find . -iname '.*.pl*'

….

Reviewing complete list of all hidden files is also often useful to determine shitty cracker stuff

 find . -iname ".*"

Debugging via  /var/log/phpmail.log enablement is useful but is more recommended on development and staging (QA) environments. Having it enable on productive server with high amounts of mail sent via PHP scripts or just on dedicated shared site server could cause both performance issues, hard disk could quickly get and most importantly could be a severe security hole as information from PHP scripts could be potentially exposed to external parties.

PHP: Better Webhosting Security – Disable exec(), exec_shell(), system(), popen(), eval() … shell fork functions

Sunday, June 23rd, 2013

increase php security better php security by disabling fork shell system and eval functions

If you work as System Administrator of WebHosting company, you definitely know how often it is that some automated cracker scripts (working as worms) intrude through buggy old crappy custom coded sites or unupdated obsolete Joomla / WordPress etc. installs. and run themselves trying to harvest for other vulnerable hosts. By default PHP enables running commands via shell with PHP functions like exec();, shell_exec(); , system();. and those script kiddie scripts use mainly this functions to spawn shell via vulnerable PHP app. Then scripts use whether php curl support is installed (i.e. php5-curl) to download and replicate itself to next vulnerable hop.

With that said it is a must after installing new Linux based server for hosting to disable this functions, to save yourself from future hassles …
Earlier, I blogged how to disable PHP system system(); and exec(); functions to raise Apache security using suhosin however this method requires php suhosin being used.

Yesterday, I had to configure new web hosting server with Debian 7, so I tried installing suhosin to use it to protect PHP from having enabled dangerous system();, eval(); exec(); .
I remember disabling system(); using suhosin php extension was working fine on older Debian releases, however in Debian 6.0, php5-suhosin package was causing severe Apache crashes and probably that's why in latest Debian Wheezy 7.0, php suhosin extension is no longer available. Therefore using suhosin method to disable system();, exec(); and other fork functions is no longer possible in Debian.

Since, suhosin is no longer there, I decided to use conventional PHP method via php.ini.

Here is how to do it

Edit:

/etc/php5/apache2/php.ini

debian:~# vim /etc/php5/apache2/php.ini
And near end of file placed:

disable_functions =exec,passthru,shell_exec,system,proc_open,
popen,curl_exec, curl_multi_exec,parse_ini_file,show_source

allow_url_fopen Off
allow_url_include Off

It is good to explain few of above functions – shell_exec, proc_open, popen, allow_url_fopen,show_source  and allow_url_include.

Disabling shell_exec – disables from PHP scripts executing commands with bash slash ` `, i.e. `ls`. proc_open and popen allows reading files from file system.

show_source – makes possible also reading other PHP source files or can be used to display content of other files from fs.

To read newly placed config vars in php.ini usual apache restart is necessary:

debian:~# /etc/init.d/apache2 restart
[….] Restarting web server: apache2
. ok

Further on tо test whether system();, exec();, passthru(); … etc. are disabled. Make new PHP file with content:

<?php
error_reporting(E_ALL);
$disabled_functions = ini_get('disable_functions');
if ($disabled_functions!='')
{
    $arr = explode(',', $disabled_functions);
    sort($arr);
    echo 'Disabled Functions:
        ';
    for ($i=0; $i<count($arr); $i++)
    {
        echo $i.' - '.$arr[$i].'<br />';
    }
}
else
{
    echo 'No functions disabled';
}
?>

php show disabled functions screenshot improve php security by disabling shell spawn functions

Copy of above source code show_disabled_php_functions.php is here for download
. To test your Apache PHP configuration disabled functions download it with wget or curl and rename it to .php:

# cd /var/www # wget -q http://www.pc-freak.net/files/show_disabled_php_functions.php.txt
mv show_disabled_php_functions.php.txt show_disabled_php_functions.php

After disabling functions on those newly setup Debian hosting Apache webserver, I remembered, same functions were still active on another CentOS Linux server.

To disable it there as well, had to edit:

/etc/php.ini

[root@centos:~]# vim /etc/php.ini

And again place after last file line;

disable_functions =exec,passthru,shell_exec,system,proc_open,popen,
curl_exec, curl_multi_exec,parse_ini_file,show_source

allow_url_fopen Off
allow_url_include Off

Finally on CentOS host, had to restart Apache:

[root@centos:~]# /etc/init.d/httpd restart

For Security paranoids, there are plenty of other PHP functions to disable including, basic functions like ln, mv, mkdir, cp, cat etc.

Below is list of all functions to disable – only disable this whether you you're a PHP security freak and you're 100% some server hosted website will not use it:

disable_functions = "ln, cat, popen, pclose, posix_getpwuid, posix_getgrgid, posix_kill, parse_perms, system, dl, passthru, exec, shell_exec, popen, proc_close, proc_get_status, proc_nice, proc_open, escapeshellcmd, escapeshellarg, show_source, posix_mkfifo, mysql_list_dbs, get_current_user, getmyuid, pconnect, link, symlink, pcntl_exec, ini_alter, pfsockopen, leak, apache_child_terminate, posix_kill, posix_setpgid, posix_setsid, posix_setuid, proc_terminate, syslog, fpassthru, stream_select, socket_select, socket_create, socket_create_listen, socket_create_pair, socket_listen, socket_accept, socket_bind, socket_strerror, pcntl_fork, pcntl_signal, pcntl_waitpid, pcntl_wexitstatus, pcntl_wifexited, pcntl_wifsignaled, pcntl_wifstopped, pcntl_wstopsig, pcntl_wtermsig, openlog, apache_get_modules, apache_get_version, apache_getenv, apache_note, apache_setenv, virtual, chmod, file_upload, delete, deleted, edit, fwrite, cmd, rename, unlink, mkdir, mv, touch, cp, cd, pico"

Disabling PHP system(); and exec(); functions to raise up Apache security on Debian GNU / Linux

Wednesday, July 18th, 2012

Disabling PHP system(); and exec(); functions to raise up Apache security on Debian Gnu / Linux

At security critical hosts running Apache + PHP based sites it is recommended functions like:

system();
exec();shell_exec();.....

to be disabled. The reason is to mainly harden against script kiddies who might exploit your site/s and upload some shitty SK tool like PHP WebShell, PHP Shell and the probably thousands of “hacker” variations that exist nowdays.

In latest Debian stable Squeeze, suhosinadvanced protection module for php5 is being installed and enabled in Apache (by default).
Simply disabling a number of functions using suhosin, could prevent multiple of future headaches and hours of pondering on who 0wn3d your server ….

Disabling the basic PHP system(); and other similar functions which allows shell spawn is not always possible, since some websites or CMS platforms depends on them for proper runnig, anyways whether it is possible disabling ’em is a must.
There are two ways to disable system(); functions; One is through using /etc/php5/apache2/conf.d/suhosin.ini and 2nd by adding a list of functions that has to be disabled directly in Website Virtualhost file or in apache2.conf (/etc/apache2/apache2.conf;
For people hosting multiple virtualhost websites on the same server using the custom domain Virtualhost method is probably better, since on a global scale the functions could be enabled if some of the websites hosted on the server requires exec(); to work OK. In any case using /etc/php5/apache2/conf.d/suhosin.ini to disable system(); functions in PHP is less messy …

1. Disabling PHP system(); fuctions through /etc/apache2/apache2.conf and custom site Vhosts

Place somewhere (I prefer near the end of config);;;


php_admin_flag safe_mode on
php_admin_value disable_functions "system, exec, shell_exec, passthru , ini_alter, dl, pfsockopen, openlog, syslog, readlink, symlink, link, leak, fsockopen, popen, escapeshellcmd, apache_child_terminate apache_get_modules, apache_get_version, apache_getenv, apache_note,apache_setenv,virtual"

Disabling it for custom virtualhost is done by simply adding above Apache directvies (before the closing tag in /etc/apache2/sites-enabled/custom-vhost.com

2. Disabling PHP system();, exec(); shell spawn with suhosin.ini

In /etc/php5/apache2/conf.d/suhosin.ini add;;

suhosin.executor.func.blacklist =system, exec, shell_exec, passthru, ini_alter, dl,
pfsockopen, openlog, syslog, readlink, symlink, link, leak, fsockopen, popen,
escapeshellcmd, apache_child_terminate apache_get_modules, apache_get_version,
apache_getenv, apache_note,apache_setenv,virtual

To do it directly via shell issue;;;

server: conf.d/# cd /etc/php5/apache2/conf.d/
server: conf.d# echo 'suhosin.executor.func.blacklist =system, exec, shell_exec, passthru, ini_alter, dl,' >> suhosin.ini
server: conf.d# echo 'pfsockopen, openlog, syslog, readlink, symlink, link, leak, fsockopen, popen,' >> suhosin.ini
server: conf.d# echo escapeshellcmd, apache_child_terminate apache_get_modules, apache_get_version,' >> suhosin.ini
server: conf.d# echo 'apache_getenv, apache_note,apache_setenv,virtual' >> suhosin.ini

Then to re-load the memory loaded Apache libphp library an Apache restart is necessary;

server: conf.d# /etc/init.d/apache2 restart
Restarting web server: apache2 ... waiting .
server: conf.d#

Tadam, this should be quite a good security against annoying automated script attacks. Cheers 😉

How to disable tidy HTML corrector and validator to output error and warning messages

Sunday, March 18th, 2012

I've noticed in /var/log/apache2/error.log on one of the Debian servers I manage a lot of warnings and errors produced by tidy HTML syntax checker and reformatter program.

There were actually quite plenty frequently appearing messages in the the log like:

...
To learn more about HTML Tidy see http://tidy.sourceforge.net
Please fill bug reports and queries using the "tracker" on the Tidy web site.
Additionally, questions can be sent to html-tidy@w3.org
HTML and CSS specifications are available from http://www.w3.org/
Lobby your company to join W3C, see http://www.w3.org/Consortium
line 1 column 1 - Warning: missing <!DOCTYPE> declaration
line 1 column 1 - Warning: plain text isn't allowed in <head> elements
line 1 column 1 - Info: <head> previously mentioned
line 1 column 1 - Warning: inserting implicit <body>
line 1 column 1 - Warning: inserting missing 'title' element
Info: Document content looks like HTML 3.2
4 warnings, 0 errors were found!
...

I did a quick investigation on where from this messages are logged in error.log, and discovered few .php scripts in one of the websites containing the tidy string.
I used Linux find + grep cmds find in all php files the "tidy "string, like so:

server:~# find . -iname '*.php'-exec grep -rli 'tidy' '{}' ;
find . -iname '*.php' -exec grep -rli 'tidy' '{}' ; ./new_design/modules/index.mod.php
./modules/index.mod.php
./modules/index_1.mod.php
./modules/index1.mod.php

Opening the files, with vim to check about how tidy is invoked, revealed tidy calls like:

exec('/usr/bin/tidy -e -ashtml -utf8 '.$tmp_name,$rett);

As you see the PHP programmers who wrote this website, made a bigtidy mess. Instead of using php5's tidy module, they hard coded tidy external command to be invoked via php's exec(); external tidy command invocation.
This is extremely bad practice, since it spawns the command via a pseudo limited apache shell.
I've notified about the issue, but I don't know when, the external tidy calls will be rewritten.

Until the external tidy invocations are rewritten to use the php tidy module, I decided to at least remove the tidy warnings and errors output.

To remove the warning and error messages I've changed:

exec('/usr/bin/tidy -e -ashtml -utf8 '.$tmp_name,$rett);

exec('/usr/bin/tidy --show-warnings no --show-errors no -q -e -ashtml -utf8 '.$tmp_name,$rett);

The extra switches meaning is like so:

q – instructs tidy to produce quiet output
-e – show only errors and warnings
–show warnings no && –show errors no, completely disable warnings and error output

Onwards tidy no longer logs junk messages in error.log Not logging all this useless warnings and errors has positive effect on overall server performance especially, when the scripts, running /usr/bin/tidy are called as frequently as 1000 times per sec. or more

Speeding up Apache through apache2-mpm-worker and php5-cgi on Debian / How to improve Apache performance and decrease server memory consumption

Friday, March 18th, 2011

speeding up apache through apache2-mpm-worker and php5-cgi on Debian Linux / how to improve apache performance and decrease server responce time
By default most Apache running Linux servers on the Internet are configured to use with the mpm prefork apache module
Historically prefork apache module is the predecessor of the worker module therefore it's believed to be a way more tested and reliable, if you need a critical reliable webserver configuration.

However from my experience by so far with the Apache MPM Worker I can boldly say that many of the rumors concerning the unreliabity of apache2-mpm-worker are just myths.

The old way Apache handles connections e.g. the mod prefork is the well known way that high amount of the daemons on Linux and BSD are still realying on.
When prefork is a used by Apache, every new TCP/IP connection arriving at your Linux server on the Apache configured port let's say on port 80 is being served by Apache in a way that the Apache process (mother process) parent does fork a new Apache parent copy in order to serve the new request.
Thus by using the prefork Apache needs to fork new process (if it doesn't have already an empty forked one waiting for connections) and serve the HTTP request of the new client, after the request of the client is completed the newly forked Apache usually dies (even though it again depends on the way the Apache server is configured via the Apache configuration – apache2.conf / httpd.conf etc.).

Now you can imagine how slow and memory consuming it is that all the time the parent Apache process spawns new processes, kills old ones etc. in order to fulfill the client requests.

Now just to compare the Apace mpm prefork does not use the old forking way, but relies on a few Apache processes which handles all the requests without constantly being destroyed and recreated like with the prefork module.
This saves operations and system resources, threaded programming has already been proven to be more efficient way to handle tasks and is heavily adopted in GUI programming for instance in Microsoft Windows, Mac OS X, Linux Gnome, KDE etc.

There is plenty of information and statistical data which compares Apache running with prefork and respectively worker modules online.
As the goal of this article is not to went in depths with this kind of information I would not say more on it but let you explore online a bit more about them in case if you're interested.

The purpose of this article is to explain in short how to substitute the Apache2-MPM-Prefork and how your server performance could benefit out of the use of Apache2-MPM-Worker.
On Debian the default Apache process serving module in Apache 1.3x,Apache 2.0x and 2.2x is prefork thus the installation of apache2-mpm-worker is not "a standard way" to install Apache

Deciding to swith from the default Debian apache-mpm-prefork to apache-mpm-worker is quite a serious and responsible decision and in some cases might cause troubles, if you have decided to follow my article be sure to consider all the possible negative consequences of switching to the apache worker !

Now after having said a bunch of info which might be not necessary with the experienced system admin I'll continue on with the steps to install the apache2-mpm-worker.

1. Install the apache2-mpm-worker

debian:~# apt-get install apache2-mpm-worker php5-cgi
Reading state information... Done
The following packages were automatically installed and are no longer required:
The following packages will be REMOVED apache2-mpm-prefork libapache2-mod-php5
The following NEW packages will be installed apache2-mpm-worker
0 upgraded, 1 newly installed, 2 to remove and 46 not upgraded.
Need to get 0B/259kB of archives.After this operation, 6193kB disk space will be freed.

As you can notice in below's text confirmation which will appear you will have to remove the apache2-mpm-prefork and the apache2-mpm-worker modules before you can proceed to install the apache2-mpm-prefork.

You might ask yourself if I remove my installed libphp how would I be able to use my Apache with my PHP based websites? And why does the apt package manager requires the libapache2-mod-php5 to get removed.
The explanation is simple apache2-mpm-worker is not thread safe, in other words scripts which does use the php fork(); function would not work correctly with the Apache worker module and will probably be leading to PHP and Apache crashes.
Therefore in order to install the apache mod worker it's necessary that no libapache2-mod-php5 is existent on the system.
In order to have a PHP installed on the server again you will have to use the php5-cgi deb package, this is the reason in the above apt-get command I'm also requesting apt to install the php5-cgi package next to apache2-mpm-worker.

2. Enable the cgi and cgid apache modules

debian:~# a2enmod cgi
debian:~# a2enmod cgid

3. Activate the mod_actions apache modules

debian:~# cd /etc/apache2/mods-enabled
debian:~# ln -sf ../mods-available/actions.load
debian:~# ln -sf ../mods-available/actions.conf

4. Add configuration options in order to enable mod worker to use the newly installed php5-cgi

Edit /etc/apache2/mods-available/actions.conf vim, mcedit or nano (e.g. your editor of choice and add inside:

&ltIfModule mod_actions.c>
Action application/x-httpd-php /cgi-bin/php5
</IfModule>

After completing all the above instructions, you might also need to edit your /etc/apache2/apache2.conf to tune up, how your Apache mpm worker will serve client requests.
Configuring the <IfModule mpm_worker_module> in apache2.conf is necessary to optimize your newly installed mpm_worker module for performance.

5. Configure the mod_worker_module in apache2.conf One example configuration for the mod worker is:

<IfModule mpm_worker_module>
StartServers 2
MaxClients 150
MinSpareThreads 25
MaxSpareThreads 75
ThreadsPerChild 25
MaxRequestsPerChild 0
</IfModule>

Consider the fact that this configuration is just a sample and it's in no means configured for serving Apache requests for high load Apache servers and you need to further play with the values to have a good results on your server.

6. Check that all is fine with your Apache configurations and no syntax errors are encountered

debian:~# /usr/sbin/apache2ctl -t
Syntax OK

If you get something different from Syntax OK track the error and fix it before you're ready to restart the Apache server.

7. Now restart the Apache server

debian:~# /etc/init.d/apache2 restart

All should run fine and hopefully your PHP scripts should be interpreted just fine through the php5-cgi instead of the libapache2-mod-php5.
Using the /usr/bin/php5-cgi will increase with some percentage your server CPU load but on other hand will drasticly decrease the Webserver memory consumption.
That's quite logical because the libapache2-mod-hp5 is loaded once during apache server whether a new instance of /usr/bin/php5-cgi is invoked during each of Apache requests via the mod worker.

There is one serious security flow coming with php5-cgi, DoS against a server processing scripts through php5-cgi is much easier to be achieved.
An example for a denial attack which could affect a website running with mod worker and php5-cgi, could be simulated from a simple user with a web browser which holds up the f5 or ctrl + r browser page refresh buttons.
In that case whenever php5-cgi is used the CPU load would rise drastic, one possible solution to this denial of service issues is by installing and using libapache2-mod-evasive like so:

8. Install libapache2-mod-evasive

debian:~# apt-get install libapache2-mod-evasive
The Apache mod evasive module is a nice apache module to minimize HTTP DoS and brute force attacks.
Now with mod worker through the php5-cgi, your apache should start serving requests more efficiently than before.
For some performance reasons some might even want to try out the fastcgi with the worker to boost the Apache performance but as I have never tried that I can't say how reliable a a mod worker with a fastcgi would be.

N.B. ! If you have some specific php configurations within /etc/php5/apache2/php.ini you will have to set them also in /etc/php5/cgi/php.ini before you proceed with the above instructions to install Apache otherwise your PHP scripts might not work as expected.

Mod worker is also capable to work with the standard mod php5 Apache module, but if you decide to go this route you will have to recompile your PHP lib manually from source as in Debian this option is not possible with the default php library.
This installation worked fine on Debian Lenny but suppose the same installation should work fine on Debian Squeeze as well as Debian testing/unstable.
Feedback on the afore-described mod worker installation is very welcome!