Setting up an SSH Config File

If you are frequently using SSH to connect to several servers, with several permission files, and different usernames – then maybe a SSH Config file is for you. It tells SSH which settings and options to use when connecting to different servers.

To set this up, create a file called

~/.ssh/config

And add instructions. Here is a sample that might help.

Host ns?.redronin.com, ns?
  User root
  IdentityFile ~/.ssh/redronin.pem

Host red
  User root
  HostName red.redronin.com

Host ec2-1-2-3-4.compute-1.amazonaws.com, db-slave
  User root
  IdentityFile ~/.ssh/redronin-us-east.pem
  HostName ec2-1-2-3-4.compute-1.amazonaws.com

Host *.ap-southeast-1.compute.amazonaws.com
  User ubuntu
  IdentityFile ~/.ssh/redronin-ap-singapore.pem

Host *.us-west-1.compute.amazonaws.com
  User ubuntu
  IdentityFile ~/.ssh/redronin-us-west.pem

Host *.compute-1.amazonaws.com
  User ubuntu
  IdentityFile ~/.ssh/redronin-us-east.pem

You will notice I indented the options for ease of reading, but this is optional. The Host variable differentiates different servers. You can use * and ? and comma deliminate multiple options.

The most useful settings are

• User
• HostName
• IdentityFile
• Port

But there is a heap more http://www.openbsd.org/cgi-bin/man.cgi?query=ssh_config&sektion=5