Running 2 ssh instances

[Sylvain <sylvaintersideral@gmail.com>]

Hello,

I have a server with an ssh instance configured to run on port 22. I 
also configured iptables to have a port-knocking mechanism blocking 
connections on port 22.

Now I'd like to run another (restricted) ssh instance for just 1 
particular user, without this port-knocking stuff. I tried creating a 
chroot with a particular ssh config, but even though the ssh instance is 
running in the chroot environment, it seems to be using the users of the 
base system, not the ones defined in the jail, which renders the whole 
thing useless. I found some docs about ChrootDirectory but that won't 
work since chroot is done after the authentication has completed.

Right now I'm a bit confused by the way chroot seems to work with users. 
I'd be grateful if someone had an idea on how to do have an ssh instance 
running on a specific port and allowing only certain users.

Thanks,
Sylvain