S/KEY Authentication

This guide shows you how you can enable S/KEY one-time password authentication on your Arch.

Warning: Do following actions on secure connection from a secure computer. A chain is as strong as its weakest link.

Install opie

From aur, install following packages:

* libpam-opie
* opie-client
* opie-server

(As of today 2010-05-17 packages does not seem to support x86_64 but there is posted a fix on comments of opie-client)

In /etc/pam.d tweak config files for wanted logins. I tweaked sshd and sudo. Do the following to selected files:

auth  required  pam_unix.so
change to (note order)-->
auth sufficient pam_unix.so
auth sufficient pam_opie.so

If you want to use SSH, change ChallengeResponseAuthentication to yes in /etc/ssh/sshd_config

As your user (no root), run:

# opiepasswd -c

After entering a passphrase you get your OTP key:

ID busk OTP key is 499 fe6839
MIRE MORE ODE DOME REAM

# opiekey -n 20 499 fe6839

OR alternative way for Java-enabled mobile phone owners: Get VeJotp, It's free and you can generate passwords on the run.

Now, when you ssh to your box, hit Enter to the password prompt and you will be prompted for onetime password.

This guide is based on [1]