Michel Belleau:
I use HAProxy and STunnel and I had to do a new installation lately. I took time to check the latest versions available of each product as this is a good time to test it out before production roll-out. I figured out that enough things have changed from STunnel version 4.44 to 4.46 making the X-Forwarded-For patch (that is usually used when STunnel sits in front of HAProxy) reject some parts of the latest 4.44 patch I found on the internet.
The "usual" way is not always the best one. Do not use X-Forwared-For with haproxy. Instead use "protocol = proxy" option of stunnel 4.45 or later, and accept-proxy bind option of haproxy 1.5-dev3 or later.
PS: I didn't try it yet for IPv6 connections yet.
PS: "protocol = proxy" supports IPv6.
Mike