SSH-LPR Backend for CUPS

So, you want to print from off campus or your personal notebook on campus? Well, it's easy with CUPS. This is a SSH-LPR backend that lets you create printers on remote systems that you can only access through SSH. For this to work, you are going to need CUPS, OpenSSH and a remote host with lpr. You must be able to log into the system without entering a password. That is, using a password-less key pair.

To begin, copy the following into /usr/lib/cups/backend/sshlpr and make it executable.

SSH-LPR Script Follow Link

Now, restart CUPS and add a printer. Select the SSH-LPR back end and enter a URI in the form sshlpr://[[localuser:]remoteuser@]server/queue where remoteuser is the remote user-name if it is different from the local name of the user who is printing, localuser is the user account the request should be made from if it is different from the user who is making the request, server is the host you want and queue is the remote printer name.

So, say you want to print to the GAFF lab. Let's say your user accounts are the same (i.e., your home user name is the same as your NEXUS user-name) and your classmate also has an account on your system also with harmonised names. Then, you can use the URI sshlpr://engage.uwaterloo.ca/gaff. Now, say your user-names are different, but you want to print as jrhacker, then you can use sshlpr://jrhack@engage.uwaterloo.ca/gaff. This requires that each of you has a key in jrhacker's account on Engage. If you want to just use one pair, stored in the local user jay, then use sshlpr://jay:jrhack@engage.uwaterloo.ca/gaff.

Now, to print, just use it like any other CUPS printer.

This script makes use of su to become users to access their SSH keys. If CUPS runs as root, this is not a problem, but if it does not, you will need to add a line printuser:ALL:NOPASS to /etc/suauth where printuser is the user that CUPS runs as.

And a quick way to dump all the printer names in the printcap file is grep "^[a-z].*:" /etc/printcap | /usr/bin/sed -e '/^lp/d;s/[:|].*//'.

Sat, 18 Sep 2010 08:11:14 -0400 View History