Nagios - Favorite Linux Monitoring Application! by linux journal.

http://www.linuxjournal.com/article/10451

Favorite Linux Monitoring Application

Nagios (51%)

Honorable Mention

Hyperic HQ (15%)

up.time (11%)

Nagios was not only recently dubbed one of the most important open-source apps of all time, but it also is the winner of the new Readers' Choice category, Favorite Linux Monitoring Application. A slim majority 51% of you use Nagios to keep close tabs on your networks of all shapes, sizes and levels of complexity. Most of you not using Nagios opt for the Honorable Mention candidates, Hyperic HQ (with 15%) and up.time (11%). Ganglia and GroundWork also garnered respectable votes in the single digits.

Easy remote syslog-ng setup

This is on CentOS, of course you already have regular syslog installed so download syslog-ng rpm from wherever and install...

Force its install via:

sudo rpm --force -Uvh syslog-ng-1.6.12-1.el5.centos.i386.rpm

or remove the old syslog first via:

rpm -e --nodeps rsyslog

stop syslog and start syslog-ng:

sudo /etc/init.d/syslog stop && sudo /etc/init.d/syslog-ng start

Test that its working via:

logger "test message" && sudo tail /var/log/messages

remove syslog from starting and setup syslog-ng to start up on boot:

sudo chkconfig syslog off && sudo chkconfig syslog-ng on && sudo chkconfig --list | grep syslog

Enable remote syslogging on the host syslog server
HOST:
sudo vi /etc/syslog-ng/syslog-ng.conf
add:

source s_network {
tcp(max-connections(5000));
udp();
};

destination d_network {
file ("/var/log/syslog-ng/$HOST/$FACILITY.log");
};

log { source(s_network);
destination(d_network);
};

Sending messages from your syslog-ng client
CLIENT:
sudo vi /etc/syslog-ng/syslog-ng.conf

destination loghost {
tcp("192.168.1.5");
};

log {
source(s_sys);
destination(loghost);
};

Add an iptables allow rule for port 514, and optionally add the -s and mention the host (much more secure)
sudo vi /etc/sysconfig/iptables
add:
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 514 -s 192.168.1.5 -j ACCEPT
restart iptables:
sudo /etc/init.d/iptables restart

Test that its working by running on the client:
logger "test to remote"

and running on the host:
tail -f /var/log/messages

If you see the msg its working .. if not, you fail... try again.