Anyone with more than one Ubuntu machine on their network should do this, basically it sets up an apt proxy server so that once a package has been downloaded once by a computer on your network, the rest can get it locally.
To install it:
sudo apt-get install apt-cacher-ng
Browse to http://localhost:3142 and you should see an error page of sorts telling you to edit apt.conf. Ubuntu however splits the apt.conf file into a directory, so instead we create a new file in that directory:
sudo nano /etc/apt/apt.conf.d/02cache
Paste the following line into the file (highlight to copy, middle click to paste):
Acquire::http { Proxy “http://192.168.1.2:3142”; };
And then press Ctrl+O to save followed by Ctrl+X to exit. Replace 192.168.1.2 with your apt cache’s IP address, or hostname if you have DNS. Using DNS is preferable if it is available, but most home networks won’t have a DNS server.
You then need to add the apt.conf.d file to each machine on your network in order for them to download their packages through your proxy.
See http://localhost:3142/acng-report.html for information and maintenance tasks.