Apt-Cacher NG is a caching proxy for downloading packages from Debian-style
software repositories (or possibly from other types).
The main principle is that a central machine hosts the proxy for a local
network, and clients configure their APT setup to download through it.
Apt-Cacher NG keeps a copy of all useful data that passes through it, and when
a similar request is made, the cached copy of the data is delivered without
Apt-Cacher NG has been designed from scratch as a replacement for apt-cacher,
but with a focus on maximizing throughput with low system resource
requirements. It can also be used as replacement for apt-proxy and approx with
no need to modify clients' sources.list files.