How to update multiple Ubuntu machines in a LAN quickly and efficiently saving network bandwidth?
marked as duplicate by fossfreedom♦, Jorge Castro, jrg♦, Marco Ceppi♦ Jan 3 '12 at 19:53
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apt-cacher-ng is a download proxy for software packages. The software packages are downloaded and cached on one of the Ubuntu machines on which the apt-cacher-ng daemon runs and the other Ubuntu machines can contact this machine to get the updates quickly from within the intranet.
More information on how to configure the Ubuntu machines
In order to save bandwidth, you can use an HTTP proxy like squid. If you have many machines, then you should probably have a chat with a representative from Canonical and have a look at Landscape. Or you can just install openssh-server on all the machines and update via ssh, possibly using a script. How you do all this depends on how many machines you're talking about.