Before diving into INN's configuration, let's talk about its installation. Read this section, even if you've installed INN from one of the various Linux distributions; it contains some hints about security and compatibility.
Linux distributions included Verson INN-1.4sec for quite some time. Unfortunately, this version had two subtle security problems. Modern versions don't have these problems and most distributions include a precompiled Linux binary of INN Version 2 or later.
If you choose, you can build INN yourself. You can obtain the source from ftp.isc.org in the /isc/inn/ directory. Building INN requires that you edit a configuration file that tells INN some detail about your operating system, and some features may require minor modifications to the source itself.
Compiling the package itself is pretty simple; there's a script called BUILD that will guide you through the process. The source also contains extensive documentation on how to install and configure INN.
After installing all binaries, some manual fixups may be required to reconcile INN with any other applications that may want to access its rnews or inews programs. UUCP, for instance, expects to find the rnews program in /usr/bin or /bin, while INN installs it in /usr/lib/bin by default. Make sure /usr/lib/bin/ is in the default search path, or that there are symbolic links pointing to the actual location of the rnews and inews commands.