Sep 27 2009

Techtips Vol1 – Xen on CentOS – Migrating a Legacy Server

Xen on Centos – Migrating a legacy server

Do you have a legacy server, running legacy software, still used by your company or worse a client?  Are the developers and engineers who set it up long gone, do you have documentation on the design, anything?  No worries… I recently ran into this situation and I’ve found a very nice solution. Continue reading


Sep 7 2009

XWIKI – mysql driven Wiki

I’ve been using wiki’s for some time from phpwiki, mediawiki, etc.  They all have some pro’s and con’s.  I still like the php wiki, twiki, very much, and the java wiki, JSPWiki, but I have also grown to like XWIKI, http://xwiki.org.

It is a tomcat driven wiki with all the data in mysql, instead of txt files like the aforementioned wiki’s.  This makes for good security, backup, recovery, etc.  Albeit it does seem to run a little slower.  Below are my basic install notes, enjoy… Continue reading


Sep 7 2009

Must Read for all IT Admins!!

My Favorite

– Tell Your Users What You Are Going to Do
– Tell Your Users What You Are Doing
– Tell Your Users What You Have Done

http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/admin-primer/


Sep 7 2009

Color in Mac iTerm

In .profile (if you use MacPorts) or .bash_profile

export TERM=xterm-color alias ls=’ls -G’ alias ll=’ls -hl’


May 20 2009

Horde Disable IP Address Check

/usr/share/horde/config/conf.php

Change the following line;

$conf[‘auth’][‘checkip’] = true;

to be this;

$conf[‘auth’][‘checkip’] = false;


May 10 2009

Nagios + NPC + Cacti

Nagios + Cacti + NPC Plugin Install Instructions on Centos 5 I will post a full Nagios 3.x installation instruction later (yum install nagios). For the below, I will assume you have Nagios 3.x running and have a basic knowledge of Linux, file paths, commands, etc. Continue reading


Apr 29 2009

QMAIL SMTP IP Address

When mail is sent from my server, Qmail uses not right IP for the connection. How do I change the IP that is used for any outgoing connection from my server?
Article ID: 1190
Last Review: Oct,6 2008
Author: Last updated by: system APPLIES TO:
  • Parallels Plesk Panel for Linux/Unix

Resolution

Default IP for an outgoing connections can be set using ‘ip’ utility. First of all check how routing is configured on the server:
# /sbin/ip route 192.168.50.0/24 dev eth1 proto kernel scope link src 192.168.50.53 169.254.0.0/16 dev eth1 scope link default via 192.168.50.254 dev eth1
If no ‘src’ listed in ‘ip’ output for default route, then main IP on the interface is used for an outgoing connections. You can change it using:
# /sbin/ip route change default via 192.168.50.254 dev eth1 src 192.168.50.100
Now:
/sbin/ip route 192.168.50.0/24 dev eth1 proto kernel scope link src 192.168.50.53 169.254.0.0/16 dev eth1 scope link default via 192.168.50.254 dev eth1 src 192.168.50.100
Note: be careful, if you set wrong IP as source you lose link to the server.
reference
http://kb.parallels.com/en/1190

Apr 26 2009

Nagios Monitoring Agent

  • Installed using Yum Install Nagios
  • Installed to /etc/nagios
    • nagios.cfg defines the commands file and location of the other config files
    • commands.cfg defines the scripts located in /usr/lib or lib64/nagios/plugins/ to be run
      • i.e. $USER1$/check_http -H $HOSTADDRESS$ -S -a nagioscheck:nag1oscheck
    • Within /etc/nagios/etc there are hosts.cfg, services.cfg, servicegroups.cfg, hostgroups.cf, contacts.cfg, and contactgroups.cfg
    • hosts.cfg contains any device that needs to be monitored
    • services.cfg defines the specific monitoring service and warning/critical parameters if any
    • servicgroups.cfg is used to organize in the web view
    • hostgroups.cfg matches the hosts in hosts.cfg to the services in services.cfg
    • In order to login to nagios, the ldap user must be listed in the contacts.cfg and assigned to a contactgroup
  • After making changes in nagios run “/usr/bin/nagios -v /etc/nagios/nagios.cfg” to make sure there are not any mistakes
  • service nagios restart

Apr 25 2009

Logrotate

Logrotate is an amazing tool for linux admins.  It is service called by cron in the daily cron job.  Logrotate gives you options on how you want to manage any log file.

  • Archive
  • Compress
  • Reset
  • etc.

To configure logrotate for specific log files from Apache, tomcat, subversion, hudson, etc.

  • Go to /etc/logrotate.d
  • Create seperate configuration files for each application’s log file
  • /var/log/http/* { create 0640 apache apache   #This line defines who is going to own the new log file after the old one is archived and compressed missingok daily # Run this daily rotate 7 # Rotate logs every 7 days, from line above compress # Compress log files }
  • Save and check.  To test “logrotate -f /etc/logrotate.d/filename”