I Have a remote server that runs CentOS and it is over ISP firewall and I can’t run l2TP or PPTP on it.
But SSH tunnel is available.
It is possible to connect my Mikrotik router to my server with ssh tunnel, then run a VPN connection on my Router, and send all VPN traffic over ssh tunnel?
I don’t have much experience with ssh tunnels, especially in RouterOS, but aren’t those only for tcp? That wouldn’t work for L2TP or PPTP without some additional tunnel, but SSTP or OpenVPN would be possible. With those, you should be able to simply forward port to server through ssh and run the VPN server there.