April 2013
M T W T F S S
1234567
891011121314
15161718192021
22232425262728
2930  

Categories

April 2013
M T W T F S S
1234567
891011121314
15161718192021
22232425262728
2930  

check_fping,check_ping,check_icmp

With Nagios using check_icmp is the way to go, it better and faster, below is an example configuration directive for setting the check-host-alive command which will be used by each host check.

# ‘check-host-alive’ command definitiondefine command{command_name check-host-alivecommand_line $USER1$/check_icmp -H $HOSTADDRESS$ -w 30,5% -c 100,20% -p 1}

 

time ./check_icmp -H 10.60.48.244 -n 5

OK […]

VI – Search and Replace with a pathname

Find and replace with VI on a pathname is a bit tricky you ned to use escape characters.

In this case /bin/mail should be replaced with /usr/bin/mail

The command below would do it:

:%s/\/bin\/mail/\/usr\/bin\/mail/g

 

Find and Replace Example

Here is an example of find and replace with VI, this will replace every instance of […]

Detecting DDoS attacks with Nagios

DDOS attacks are under the limelight (and the media) from the Wikileaks affair.It is quite difficult to detect attack because unlike most “traditional” attacks, it is based on the fact that flood the target machine requests from a large number of zombie machines (ie infected a program that will launch an attack).In this post we […]

Rebuild corrupt RPM database

Sometimes RPM databases become corrupt. You will no longer be able to install/upgrade/remove programs using YUM or RPM command. Even RPM quey simply gets hung.This is the case when you need to repair RPM databases.

To repair do the following:

cp -rp /var/lib/rpm{,`data +%F`.bk} This command is to take a backup of ‘ /var/lib/rpm‘ […]

Apache logs

irst locate the log file for your site. The generic log is generally at /var/log/httpd/access_log or/var/log/apache2/access_log (depending on your distro). For virtualhost-specific logs, check the conf files or (if you have one active site and others in the background) run ls -alt /var/log/httpd to see which file is most recently updated.

cat access.log| awk ‘{print […]

Netstat

HOW TO CHECK WHETHER LINUX SERVER IS UNDER DDOS ATTACK

DDOS – Distributed Denial of service attack

DDOS or DOS (Denial of service ) is an attack in the server , where the server resources become unavailable to the users. It can be typically defined as the loss of network connectivity and […]