I would like to detect the usage of ssh on port 443 on a linux gateway. A kind of counter measure against stuff like sslh. I think netfilter and iptables would be the solution, but can't find module that fits.
(edit) At this time it is not a problem for me to prohibe direct connexion to 443 but allow for example a proxy.
So if it is not possible at L7 filtering, is there a proxy solution that permit this filtering.