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The following linux security document will help you to tweak on the linux server for the security stuff
and help you how do you know whether you’ve been compromised or not?

1. Exim.
Enable extended logging :
Add the following line in exim, below the first line recommended
log_selector = +address_rewrite +all_parents +arguments
+connection_reject +delay_delivery +delivery_size +dnslist_defer
+incoming_interface +incoming_port +lost_incoming_connection +queue_run
+received_sender +received_recipients +retry_defer +sender_on_delivery
+size_reject +skip_delivery +smtp_confirmation +smtp_connection
+smtp_protocol_error +smtp_syntax_error +subject +tls_cipher +tls_peerdn
+\

Fommail Trap
http://void.thunderteam.org/fm-trap.html

For Securing Exim this could be a Good resource
http://www.rvskin.com/index.php?page=public/antispam

2. Httpd :

install mod_security
install mod_dosevasive (causes problem with FP sometimes though)

3. PHP

disable_functions = “system,exec”

eAccelerator for PHP acceleration
http://sourceforge.net/projects/eaccelerator

4. Some small recommended apps

Install BFD from rfxnetworks.net
Install LSM from rfxnetworks.net
APF from rfxnetworks.net ( since we have portsentry not really required )
rkhunter can be found on www.rootkit.nl

5. cpanel script to disable compilers incase we have not done this yet
/scripts/compilers off

6. MYSQL

mysql query cache
vi /etc/my.cnf
query-cache-type = 1
query-cache-size = 100M
100M can be changed according to how busy the server is

7. Securing some binaries

chmod 750 /usr/bin/rcp
chmod 750 /usr/bin/wget
chmod 750 /usr/bin/lynx
chmod 750 /usr/bin/links
chmod 750 /usr/bin/scp
chmod 000 /etc/httpd/proxy/

Also consider to check this;

* Check your log files,
* Look for setuid/setgid files, especially if they are owned by root
* Check what your integrity checker has to say about your system binaries
* Check for packet sniffers which may or may not be running
* If you didn’t install it, it shouldn’t be there
* Check your crontabs and at queues.
* Check for services that shouldn’t be running on your system
* Check /etc/passwd for new accounts/inactive accounts that have suddenly become active

This entry was posted on Thursday, October 2nd, 2008 at 1:16 pm and is filed under Linux Hosting. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.