apt-cacher and apt-cacher-ng both act as a proxy between apt-get or aptitude and the Debian repositories. It stores the packages upon first request and loads them from cache on further ones. If you have 2 or more Ubuntu PCs in your network, you can save a massive amount of bandwidth with it.

Installation

1. Install the package apt-cacher or apt-cacher-ng
2. Make sure it is running (sometimes you might have to edit a file /etc/default/apt-cacher or
   /etc/default/apt-cacher-ng to enable it)
3. Now do the following on ALL PCs in your network – including the one with apt-cacher(-ng) installed:
   • Create a file /etc/apt/apt.conf.d/01proxy with the following contents: (replace the IP by the IP of the PC with apt-cacher(-ng) installed)
     Acquire::http::Proxy "http://192.168.0.1:3142";
   • Create a file /etc/apt/apt.conf.d/99clean with the following contents: (this will keep the local apt-cache clean)
     DPkg::Post-Invoke {"/usr/bin/find /var/cache/apt/archives/ -type f -mtime 2 -name *.deb -exec /bin/rm -f {} \; || true";};

That was it. All packages will be cached on the apt-cacher(-ng)-PC and the local caches will be kept clean.