HAProxy is a simple and fast load-balancer. For HTTP it works quite similar to 'pound' or Nginx. It can also load-balance plain TCP connections which enables it handle many more protocols like SSH, the Git protocol, SMTP, IMAP and many more.
HAProxy can simply be installed using pakfire. You will find the configuration files in
You can find a very good and detailed configuration manual on the official HAProxy homepage at http://www.haproxy.org/#docs.
This example will make HAProxy listen on port 25 and forward all connections to the first SMTP server (smtp01) until this is either offline or has more than 1000 connections opened. After that HAProxy will switch to the second one until a limit of 1000 concurrent connections is reached as well.
global log 127.0.0.1 local2 chroot /var/lib/haproxy pidfile /var/run/haproxy.pid maxconn 4000 user nobody group nobody daemon stats socket /var/lib/haproxy/stats defaults log global option redispatch retries 3 timeout queue 1m timeout connect 10s timeout client 1m timeout server 1m timeout check 10s maxconn 3000 listen smtp :25 mode tcp option tcplog balance first server smtp01 192.168.180.101:25 check maxconn 1000 server smtp02 192.168.180.102:25 check maxconn 1000