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Asked: 2013-09-21 02:06:23 +0800 CST

Can Bash Tell Me Which SSH Public Key Was Used To Authenticate?

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Let's say I want to track my root users. Each of them has a unique private key and their public keys have been stored in /root/.ssh/authorized_keys.

Given that each user logs in with their unique key how can I tell from within a BASH session which key was used to authenticate? I've tried looking at the environment variables when I log in but cannot see anything that correlates my session with my public key.

bash

1 Answers

  1. You could add the username to the public key in ~/.ssh/authorized_keys on the server and export it as an environment value:

    environment="REALUSER=realusername" ssh-dsa AAA...

    That will set the environment variable REALUSER which will then be available to use in bash. This will only work if PermitUserEnvironment is set to true in sshd_config

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