SSH client configuration - Multiple servers and different keys
If you just like me daily connect to multiple SSH servers, then I have a tip for you.
Typically when you connect to a server via SSH you enter a username, hostname and a password or a key. Maybe even a port number.
$ ssh user@host
There is an easier way! The SSH client is configurable. You can set up all this information in advance and just tell the client which configuration to use.
John Doe has three servers that he usually connects to. He has his own private server
doe.tld with the SSH server listening to port
1337 and two company servers
server2.company.tld. He has no keys yet, but want one for the private server and one that can be used to access both the company servers.
Let's start with the keys. He needs two keys.
$ ssh-keygen -t rsa -C "email@example.com" $ ssh-keygen -t rsa -C "firstname.lastname@example.org" -f ~/.ssh/company
He now has two keys. One for the private server and one for the company servers.
$ ls ~/.ssh/ company company.pub id_rsa id_rsa.pub
Now the keys need to be placed in the
authorized_keys file on all servers.
$ scp ~/.ssh/id_rsa.pub email@example.com: $ ssh firstname.lastname@example.org 'cat id_rsa.pub >> ~/.ssh/authorized_keys'
$ scp ~/.ssh/company.pub email@example.com: $ ssh firstname.lastname@example.org 'cat company.pub >> ~/.ssh/authorized_keys'
$ scp ~/.ssh/company.pub email@example.com: $ ssh firstname.lastname@example.org 'cat company.pub >> ~/.ssh/authorized_keys'
And now the contents of the configuration file
Host myserver Hostname doe.tld Identityfile ~/.ssh/id_rsa User john Port 1337 Host s1 Hostname server1.company.tld Identityfile ~/.ssh/company User johndoe Host s2 Hostname server2.company.tld Identityfile ~/.ssh/company User johndoe
He can now use a configuration by passing the name (
Host) as the only argument to the ssh client.
$ ssh s1
Note: You can set this up without keys and just use passwords, but I strongly recommend using keys.