SSH:TDG
SSH: The Secure Shell (The Definitive Guide)
Barrett, Silverman, & Byrnes / O’Reilly

SSH Frequently Asked Questions

I want to require different forms of authentication based on the source address of the connection (where the user is coming from).


Up until recently, this was not possible with OpenSSH. However, newer versions allow you to configure different authentication types based on various properties of the connection, including source IP address. See the sshd_config(5) section on the Match option.