Is it possible to update all LAN PCs without going to each and every PC individually? For example, I may want to apply a security update to all PCs or I may want to add or remove a package from all PCs. Is this possible?

Yes:
ssh to the PC
login
Become root
Apply the update
logout

tredegar: That is going to each and every PC individually via ssh which I do not want to do. I want to update all PCs at once. It will take a long time to update 100+ PCs by ssh'ing into each and every PC individually.

For example, a mass update

I don't know what distribution you use, but to my knowledge, Mandriva's “drakxtools” contain a GUI administration tool to do just that.

Yves.

I use Debian stable.

If you know bash scripting you can make a script to log in (using ssh), execute a command to update via apt-get, logoff and go to the next computer. Don't forget to use nohup when running apt-get.

For the script itself you can make a "for" loop with ip address. It would be nice if you test connection before trying to directly connect via ssh and to add a sleep time between connections.

For a resource with scripting you can always go to this howto.

Skuzye

Looks like this is the only way.

Cfengine is sometimes used to centrally manage a number of hosts.

If you read the Filesystem Hierarchy Standard, there are many directories which can be mounted static/shared. If all of the hosts use the same directory for /lib/,/bin/,/usr/bin/,/usr/sbin/, etcetera you can update the shared directories on the server.

If you use slim clients, then there is only one installation which can be updated.

Another idea could be to allow autoupdates by all of the hosts, but use your own mirror. That way you could control which updates are performed.

I personally liked this one suggested by jschiwal:

That would be by far the easier.

I like the mirror idea, sounds the easiest. However, if you look at my original question, it also asks about installing or removing software from all networked computers. is this also possible from a mirror to automatically add or remove software from all computers?

The good thing about the script and ssh is that once you've made the script you can run anything in each computer with just some edition to the script.

If you're in a hurry to update you can try using the mirror while you make the script

Skuzye

I've heard great things about using apt-proxy for making your own partial mirror. But getting back to the centralized update management issue: Have you searched the Debian repositories for a solution? Honestly, I'd be surprised if they didn't have a package for this sort of thing.

puppet could be your answer
http://reductivelabs.com/

http://reductivelabs.com/trac/puppet/wiki/PuppetDebian

what is the difference between apt-catcher, apt-mirror, and apt-proxy?