Vim & Vision

[ #86 ] SSH Config Permalink

Linux, Shell, SSH Added a year and a bit ago and last edited less than a year ago

Users

If you are on a system as user fredb and you want to ssh to a host where your login is superman, you would normally have to specify the username on the ssh line like so:

fredb@thishost$ ssh superman@otherhost

... but you can save yourself some typing by specifying that a ssh to otherhost should try to login as superman every time by adding some lines to your ~/.ssh/config file:

Host otherhost
    User superman

Now you can simply do this:

fredb@thishost$ ssh otherhost

... and it will ask for superman's password instead of fredb's.

Host Nicknames

You can also use your config file to specify host nicknames. Say you normally connect to longhostname.tld, you can shorten that to lhn if you like:

Host lhn
    Hostname longhostname.tld
    User jsmith

... now you simply:

$ ssh lhn

Identity Files (Keys)

If you have keys set up for your various hosts, and those keys are loaded in your ssh-agent, you might like to specify which key belongs to which host in the config file.

Host lhn
    Hostname longhostname.tld
    User jsmith
    IdentityFile ~/.ssh/id_dsa.longhostname

This is important if you have greater than 6 keys in your agent. Why? Because without this mapping, ssh-agent will iterate through its list of keys until it finds one that works - but the host will hang up after 6 unsuccessful tries! If your key is number seven in the list then it will not work. So, adding the IdentityFile mapping in the config file as above will make ssh-agent try the correct key the very first time.