The magic of ~/.ssh/config

Hi, today I want to talk about the ~/.ssh/config file.

First thing about this magic file: if you are using ssh you must have this file, this is a fact.

For example, i use git with ssh, because ssh is a very good protocol, and to use git over ssh we don’t use the TTY, so we can put in the config file something like:

Host git.kde.org
 User git
 RequestTTY no

In this way I can execute

ssh git.kde.org

without seeing the annoing “PTY allocation request failed” message.

Another sorcery happens when you have multiple ssh keys, I have one key for each “scope”, for example: one for KDE, one for GitHub, one for GitLab, one for my home, ecc.

I don’t want to use the “-i” option each time to select the right key, this is why I use the IdentityFile option, for example applyed to “*.kde.org”.

Sometime I have to connect to a server without direct access to the sshd daemon with a direct TCP connection, in this scenario i use the “ProxyCommand” option, this is a command to execute to proxy the ssh connection via another host, for example “ProxyCommand ssh bastion.<domain> nc %h %p”.

The last useful thing is that you can create an alias for an host, for example I have my server with FQDN “srv.domain.tdl” listening on port 1900 TCP, I can create an alias, like “srv” using something as:

Host srv
 HostName srv.domain.tdl
 Port 1900

With this config I can run “ssh srv” and be on my server.

Thanks for reading.