Recently I wanted to load balance a TCP service i.e. not http, in the past I've used ultramonkey but there doesn't seem to be any maintained Redhat/Centos packages.
After some googling I found that haproxy can balance non-http services but examples of non-http configurations are few and far between, this blog post lead me to my solution, so after the jump I have a haproxy.cfg which will load balance smtp round-robin style across 4 servers, you also get a webstats interface listening on http://IP:8080/haproxy?stats (username = me, password = password).
By changing the port numbers from 25 (SMTP) you can effectively load balance any TCP app :)
global log 127.0.0.1 local0 log 127.0.0.1 local1 notice maxconn 4096 chroot /var/lib/haproxy user haproxy group haproxy daemon #debug #quiet defaults log global mode http option httplog option dontlognull option redispatch retries 3 maxconn 2000 contimeout 5000 clitimeout 50000 srvtimeout 50000 listen stats :8080 balance mode http stats enable stats auth me:password listen smtp :25 mode tcp option tcplog balance roundrobin server smtp 192.168.0.1:25 check server smtp1 192.168.0.2:25 check server smtp2 192.168.0.3:25 check server smtp3 192.168.0.4:25 check
Redhat/Centos rpm packages of haproxy are avilable from Fedora's EPEL Project