haproxy transparent mode on 14.04
Solution 1:
In order to be able to use TPROXY, your SSH server must use the haproxy box as router (well, the haproxy box must be in the way of the packets, but this is the easiest way to do it).
You also need the send_redirects kernel parameter enabled:
echo 1 >/proc/sys/net/ipv4/conf/all/send_redirects
echo 1 >/proc/sys/net/ipv4/conf/eth0/send_redirects