rdup comes with a debian/ directory which allows you to build a .deb package for your own need, just like source rpms (there is a .spec file included also, if you would like to build an rpm). Currently rdup isn't carried by Debian, but this may change in the future.

Build dependencies

There are some dependencies that you must install before you can build/compile rdup on your system. You'll absolutely need to

apt-get install fakeroot dpkg-dev automake autoconf libglib2.0-dev \
libfile-copy-recursive-perl make gcc

I'm not 100% sure this is all you need: basically you need to be able to compile a C program.

Now you can download rdup, unpack it and cd to the rdup's build directory. In there you can give the following command

dpkg-buildpackage -rfakeroot -uc -us -b

This should create a debian package; if not, please let me know. Then you should be able to

cd .. ; dpkg -i rdup-<version>.deb

This will install rdup on your Debian/Ubuntu system.