Thanks to: http://www.karan.org/blog/index.php/2009/08/25/multiple-ssh-private-keys
In quite a few situations its preferred to have ssh keys dedicated for a service or a specific role. Eg. a key to use for home / fun stuff and another one to use for Work things, and another one for Version Control access etc. Creating the keys is simple, just use
ssh-keygen -t rsa -f ~/.ssh/id_rsa.work -C "Key for Word stuff"
Use different file names for each key. Lets assume that there are 2 keys, ~/.ssh/id_rsa.work and ~/.ssh/id_rsa.misc . The simple way of making sure each of the keys works all the time is to now create config file for ssh:
touch ~/.ssh/config
chmod 600 ~/.ssh/config
echo “IdentityFile ~/.ssh/id_rsa.work” >> ~/.ssh/config
echo “IdentityFile ~/.ssh/id_rsa.misc” >> ~/.ssh/config
This would make sure that both the keys are always used whenever ssh makes a connection. However, ssh config lets you get down to a much finer level of control on keys and other per-connection setups. And I recommend, if you are able to, to use a key selection based on the Hostname. My ~/.ssh/config looks like this :
Host *.home.lan IdentityFile ~/.ssh/id_dsa.home User kbsingh Host *.vpn IdentityFile ~/.ssh/id_rsa.work User karanbir Port 44787 Host *.d0.karan.org IdentityFile ~/.ssh/id_rsa.d0 User admin Port 21871
Ofcourse, if I am connecting to a remote host that does not match any of these selections, ssh will default back to checking for and using the ‘usual’ key, ~/.ssh/id_dsa or ~/.ssh/id_rsa
