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SSH cz.2 – Fast connection to the server, change .ssh/config

SSH – network connection - Szybkie łączenie z serwerem, zmiana sshconfig 2022

If we connect to the server in the console and use the ‘ssh USER @ HOSTNAME‘ command. We may be prompted for a password in this case, or not if we use the ssh key. I have described how to configure and use SSH keys so that we do not have to enter a password in another article. Today I wanted to introduce a way how you can simplify the whole thing even more by changing the .ssh/config file and using aliases.

If we use non-standard ports or keys from non-standard places in the connection, the entire command is slightly longer:

ssh -p 2202 USER@HOSTNAME
ssh -i /path/key.pem USER@HOSTNAME

Additionally, we need to remember all this information with each non-standard connection. Imagine we now have 100 such servers with a custom configuration. It would be a bit difficult to remember. Of course, we should save everything in some password manager, but we can also help ourselves in other ways.

By editing or adding the ~/.ssh /config file, we can enter aliases for each connection, along with the login method and custom options.

# open the file for editing, use vi, nano or whatever you like
$ vim ~/.ssh/config
Host alias1
    HostName 192.10.0.9
    User USERNAME

Host alias2
    HostName example.com
    Port 2202
    User USERNAME
    IdentityFile  ~/.ssh/id_example1
    IdentitiesOnly yes

Host alias3
    HostName 192.10.0.10
    User USERNAME
    PubkeyAuthentication no
  • HostName – you enter the name or IP address of the server you want to connect to
  • User – username you are going to connect to
  • Port – you enter if you connect on a non-standard port
  • IdentityFile – if you connect using a key then here you specify a non-standard key location
  • IdentitiesOnly – force only key bindings to be used
  • PubkeyAuthentication – whether to try to connect using ssh keys

For standard ports or places, the parameters can be omitted. You can find more parameters that you can use at https://www.ssh.com/ssh/config/.

Now to connect instead of using the command: 

ssh -p 2202 -i /.ssh/id_example1 [email protected]

Just use the command:

ssh alias2
ssh linux connection - use .ssh/config

If you want to know how to use ssh keys, check out this article.

SSH login without password -how to use keys
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