26 April, 2011

ssh-like login with openid

I rigged together shellinabox and mod_auth_openid with some custom PAM glue so people can log into my hobby server s0.barwen.ch with an in-browser terminal window and openid.

shellinabox is not ssh (although web-based ssh is a good approximation). Instead it seems to be AJAX-over-https (which is kinda wtf for terminal access, but hey it seems to work).

The way I've glued it together is: First you visit the login page. That is an openid protected CGI script. The script runs with your openid in $REMOTE_USER, and does three things: it maps your openid to a local username; it generates (via sudo) an authentication token for you; and it HTTP-meta-redirects you to a hacked version of shellinabox.

shellinabox gives you a login prompt, asking for username and password. My hacked version stuffs the username and authentication token from the previous step into the keyboard.

The token ends up at a custom PAM module which verifies that the token is valid (for that user, and within a small time window after issue) and lets you in.

Then you get your shell prompt.

This seems like an interesting addition to barwen.ch's collection of login methods.

If you want a play, you can sign up at s0.barwen.ch

Also, if you break this, let me know rather than deleting / ...

2 comments:

  1. Hi this is very interesting and kudos your service and what you have done here. I'm trying to do something similar with a customized webconverger colocation client kiosk. Basically just a browser-only where I will have a custom file-based homepage that will include shellinabox... however I want to have a user just to input any username and without a password and be able to login via shellinabox... then they would be in a jailed terminal via an auto-created chroot based on the username they enter... is this doable? My modifed webconverger has X restarting after 10 minutes of inactivity. So if I can get this to work I will also include in the reset X script to wipe out any user directories that were created by shellinabox. I'd be grateful for any help on this.

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  2. so is the user already logged into your homepage somehow? as long as you can call out to a unix command just before login (eg via a CGI script) and pass it the real username that you trust (eg through your own homepage login) then this should work basically the same. email me benc@hawaga.org.uk and I'll send you the code (and maybe get round to packaging it for release)

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