Switch user with "sudo su - username" using SSH keys

Question

I've been trying to use ssh keys in order to be able to switch from one user to another user on the same Linux machine/server by using sudo su - username.

What i want to do is: I have several accounts on one server. I want to lock those account with passwd -l username, and allow access only with SSH keys, by ssh-ing from one user to the other on the same machine, e.g., : [user1@server]$ ssh user2@server

I did this by copying the public key of user1 to the authorized_keys file of user2 and it works fine.

But the other thing that i would like also to do, is to be able to sudo su - user2 from user1, by using the ssh keys, so i can avoid the password prompting.

e.g., [user1@server]$ sudo su - user2

I have modified the sshd_config file, and uncomment the fields:

RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys
PasswordAuthentication no

but still i am not able to do it.

I also tried what i found on the internet regarding agent forwarding, but nothing.

Can anyone help me on how to do this or point me to the right direction?

Answer 1

sudo has nothing to do with SSH and sshd config.

What you really want is a PAM module that will use SSH public keys. I'm not sure what are your reasons as the whole idea seems a bit strange, but, well. pam_ssh is the module that does this.