I’ll be referring to the main PC that updates from official mirrors as _server_ and the other PCs as _client_. Lets start.

———————— _Server_ Config —————————-
Open a terminal on the _server_ and type

sudo apt-get install apt-cacher apache2

(yep, you’ll need a webserver)

once thats done, open /etc/apt-cacher/apt-cacher.conf in a text editor and modify to your needs.
The default port is 3142. The only thing I modified was path_map which lets you use aliases for repository hostnames

My path_map looks something like this.

path_map = ubuntu archive.ubuntu.com/ubuntu ; partner archive.canonical.com/ubuntu ; ubuntu-security security.ubuntu.com/ubuntu ; lp-compiz ppa.launchpad.net/compiz/ubuntu ; google dl.google.com/linux/deb ; ubuntutweak ppa.launchpad.net/tualatrix/ubuntu

you can use full hostnames instead of aliases, but I prefer this.

Now you need to edit /etc/default/apt-cacher and set AUTOSTART to 1.

Now restart apt-cacher

sudo /etc/init.d/apt-cacher restart

Now update the repositories and upgrade your packages

sudo apt-get update
sudo apt-get upgrade

If you’re upgrading to Intrepid Ibex from Hardy Heron, Please Check http://www.ubuntu.com/getubuntu/upgrading

After the entire upgrade completes, run this command in terminal to import existing cached archives.

sudo /usr/share/apt-cacher/apt-cacher-import.pl /var/cache/apt/archives

If it throws up an error, try

sudo /usr/share/apt-cacher/apt-cacher-import.pl -s /var/cache/apt/archives

———————— _Client_ Config —————————-
First Check if the Apt-cacher server is running by opening
http://repository-server:3142/report in your browser (‘repository-server’ here is the IP or hostname of the _server_ machine)

Then on the _client_ machines, open /etc/apt/sources.list

sudo gedit /etc/apt/sources.list

And change the mirror to your local server’s IP/hostname
for example:
(If you used path_map)

deb http://archive.ubuntu.com/ubuntu/ intrepid main restricted

changes to

deb http://repository-server:3142/apt-cacher/ubuntu intrepid main restricted

Note: replace ‘repository-server’ with your _server_’s IP or hostname (in my case 192.168.0.3)

Otherwise (If you didn’t use path_map) change it to:

deb http://apt-cacher-server/apt-cacher/archive.ubuntu.com/ubuntu/ intrepid main restricted

Do this for all lines in sources.list that you want to update via the apt-cache server.

now you can use apt-get just like before.
to upgrade to Intrepid Ibex from Hardy Heron, Check http://www.ubuntu.com/getubuntu/upgrading

and click on upgrade to ubuntu 8.10

Reference links (might help you with troubleshooting)
http://www.debuntu.org/how-to-set-up-a-repository-cache-with-apt-cacher
https://help.ubuntu.com/community/Apt-Cacher-Server

You can also upgrade using apt-p2p – Learn more on torrentfreak

And I also suggest you use bittorrent for downloading the Cd and DVD ISOs so that there is lesser stress on the mirrors. If you have to use the http/ftp mirrors, try using a local mirror or one close to your country.

Get the Torrents here

See Whats New in Intrepid Ibex