Using the SSH Config

If you are anything like the average HomeLabber, you likely have one or more Linux Servers that you manage. Managing all of those servers often requires remotely accessing them, and the quickest and easiest way to do that is via SSH.

SSH or Secure Shell is a way to remotely control your Linux servers by creating an encrypted connection between two computers, and allowing the Client to run commands on the Server being accessed.

Standard SSH requires the user to access the remote system by entering a command similar to the one below:

• ssh user@192.168.4.27

Notice that ssh is invoked. The ‘user’ username is specified, as well as the remote host currently at 192.168.4.27.

Now using this command against several servers, and memorizing several IP addresses tends to be a bit of a pain. So it is often helpful to associate a name to each server. Sometimes this can be based on function. In my case, I have named my servers after different Cities and Holds of my favorite video game. With this naming scheme, and a useful file, you can make SSH usage very simple.

• ssh user@192.168.4.27

Can now become as simple as the following:

• ssh Whiterun

Navigate to your hidden .ssh directory, which is located in your Home Directory.

• cd .ssh/
• touch config
• nano config

Create a text file, name it ‘config’. Edit this ‘config’ file and add the following lines:

• Host [SERVER_NAME]
  • HostName [SERVER_IP]
  • User [USER]

Replace the bracketed items with your own information, save the file and close. Reload the SSH daemon:

• systemctl daemon-reload

If you have added the proper server details, ie. name, username, and IP address, using SSH should be as simple as typing ‘ssh SERVER_NAME’. You will be prompted for a password. Type in the corresponding User’s password and Boom. You should be in. Simple as that.

The SSH Config file can do quite a bit more than just reduce your typing though. If you setup SSH keys for better security, (highly recommended) you can call on those SSH keys at each new session. You can also specify different SSH ports depending on the configuration of the server. Linuxize has a wonderful guide on how to use the SSH config file and how useful it can really be. More information on the SSH tool can also be found here.

Hopefully you can get some use out of the SSH config file. Don’t forget to make a backup of the file and store it away securely, if you are an avid distro-hopper like myself.

Good Luck and I hope you learned something new.