You seem to be looking for a versioning system, much like cvs.

I personally use cvs to keep track of my code, but will probably switch to subversion as soon it is a bit more stable. If you are using debian, cvs is a simple apt-get install cvs away. {There are even windows and macintosh clients for cvs, which also support ssl.}

Other non open source programs that provide versioning include BitKeeper, sourcesafe, etc.