Sometimes you have some firewall that don’t allows you to accept connection other than some specific ports let’s say that you can connect on your VPS or remote server only on the ports 80 (http) and 443 (https), but you need a port also for ssh to manage your vps/server but the port 443 is used by your Web server with its https protocol, so what can you do ?
This is where sslh comes in. It’s a really simple tool that wraps incoming connections to a port and then depending on protocol redirects it onto sshd back on port 22, or to your web server on localhost:443.