Easier ssh with .ssh config

03 Feb 2020

I didn’t know about the ~/.ssh/config file until quite recently and it’s really handy, so I thought I’d share.

~/.ssh/config lets you make what I think of as ssh aliases. You can give connections short names and specify various connection settings ‒ pretty much anything you can pass to ssh’s CLI can be configured here.

Here’s a simple example:

Host nas

Host laptop
    User laptop-me

Host someserver
    User seriousthings
    Port 10100
    PubkeyAuthentication yes
    Identityfile ~/.ssh/id_rsa_seriousthings

Host *
    PubkeyAuthentication no

I am then able to do, for example, simply:

ssh nas

These settings apply from top to bottom, cumulatively. So you want to structure this file with specific rules above general rules, otherwise the general rules will override the specific, which is not what you want.

One nice benefit is that you’ll get autocompletion of hosts defined in ~/.ssh/config when using ssh under bash or zsh (at least).

~/.ssh/config can also be used to shore up some of the leaky parts of sshing, as described here ‒ the whole page, and other articles in the series (linked at the top) are worth a read if you use ssh a decent amount.