How to Use SSH

Sources:

1. SSH Essentials: Working with SSH Servers, Clients, and Keys

Port forwarding

Suppose your local machine connecting to a remote server (IP=x.x.x.x) via ssh (port=22). Your server starts moodist on port 8080, and you connect the server with VPN.

Suppose you don't have access to ports other than 22 on the remote server due to some reason such as the contraint of VPN or the restriction of firewall. As a result, you can't visit the web page via http://x.x.x.x:8080 on your local machine.

However, You can visit the web page via ssh port forwarding:

ssh -f -N -q -L localPort:localhost:remotePort username@remoteHost

• -L: Start port forwarding.
• -f: Puts the SSH session into the background just before it executes the command. This is useful for running a long-lived SSH process.
• -N: Indicates that no remote commands will be executed, and is useful for port forwarding.
• -q: Enables quiet mode to suppress command execution outputs.
• localPort: The port number on your local machine you want to use for forwarding.
• localhost: Specifies that the forwarding is to the localhost on the remote machine.
• remotePort: The port number on the remote machine you want to forward to.
• username@remoteHost: Your login credentials and the address of the remote machine.

Now you can visit http://localhost:8080, the ssh will route the network traffic to x.x.x.x:8080, then forwarding it to the 8080 port of the server locally.

Management

Look at all ssh processes:

ps aux | grep ssh

Kill all ssh preocesses:

killall ssh