SSHD real-ip behind haproxy

In mode tcp, you neet tproxy to pass the original client IP to the server behind haproxy.

The linked article has a lot of technical background, most of which is not a problem anymore - recent versions of Linux and haproxy will most likely support tproxy out of the box.

TL;DR in the backend section, try

source 0.0.0.0 usesrc clientip