pacCacher

WARNING: This is still pretty experimental and a lot of features are not yet
implemented. Use at your own risk. ;)

What is it?
pacCacher is basically a package caching proxy. Originally it was designed for
Archlinux (archlinux.org) but other distributions like Debian will be supported, too.

What exactly does pacCacher do?
pacCacher acts as a HTTP server. It receives requests from package managers like
pacman on Archlinux (that's where the name is derived from ;)) or apt-get on Debian.
If pacCacher has stored the requested packages locally, it will deliver them directly
to the clients from the host it's running on. (Usually in your private network)
If the requested packages are not available locally, pacCacher will download them
from a specified mirror, cache them locally and deliver them to your clients.
This way you save lots of bandwith (and time) when installing or upgrading multiple 
systems, because most packages are served locally. Another advantage is that you
don't have to clone the whole remote repository, just packages that are actually used
are downloaded.

How to use it?

- Server:

To run pacCacher you need Python 3.
First edit the .conf files in pacCacher's root directory (pacCacher.conf and repos.conf).
pacCacher.conf should be pretty self-explaining.
repos.conf contains the configuration for the actual repositories.
Each category describes a repository, which is later used in the mirrorlists on your
client machines. For example:

[archlinux]
...
...

'archlinux' is the name of the repository. You can specify the local directory where it
stores files, the remote directory where it fetches files from and several other options.
Okay, if you've done that it's time to start the daemon.

Just run the following in pacCacher's root directory:
# python main.py &

This will start pacCacher in the background. If you remove the '&' you can see the
output it produces on the console.
That's it for the server side.

- Client:
Basically you just have to change the mirror for your package manager.
I'll give you an example for Archlinux.
If your pacCache host owns the IP address 192.168.0.4, pacCache listens on port 9001
and the repository in your repos.conf is called 'archlinux', 
you'll put this line in your /etc/pacman.d/mirrorlist:

Server = http://192.168.0.4:9001/archlinux/$repo/os/$arch

That's it, save your mirrorlist and sync package databases with:
# sudo pacman -Syy

Repeat this step on every client and you're done.
Have fun!