If you are truly going to try and do this outside of a Scholarship then you are going to have to learn the main tools of the trade.
Search Engines
Bug trackers
Open Source projects (OS, server program's etc)
You'll need to get hold of an old PC and run a different flavour of Operating System (Unless of course you are willing to try and learn Microsoft's OS's, however for the majority they are to bloatware, I know someone's going to say NT4/Server 2003 but it's still bloated IMHO, however it's 'easier to configure')
If you pick a linux install, by all means you could try running one of the usual OS's that people mention here. However the majority of server related OS's are Freebsd, Slackware, Fedora core to name a few. In the most part if you are wanting to create a server environment for testing things you are going to need to forget about using a GUI, you'll need to setup a SSH daemon on the system and get yourself an SSH client like PuTTY. You could use straight forwards telnet, however unless you are running that secure, you aren't going to learn much about security.
The same can be said about FTP, that's another security problem that people usually have. For the most part most security exploits are just misconfiguration's that the server administrator has done and this is usually down to the nature of how difficult the server is to configure.
This is why you'd need to read an awful lot of information on various configurations for every server package you install on your box. Some packages will require pre-requisites, some will require to be reconfigured on install others still will require a complete rebuild of the boxes Kernel and that itself is a task many people (including myself) usually find a pain in the a$z3.
This of course is only part of the overall problem, since you want to learn about the 'Network Security' this means you have to learn how to configure your LAN adapter for the particular OS and not only configure it to connect to the network but also communication on many of the layers that exist over the TCP/IP protocol.
In essence go out and get some books, either buy them online or try to find a second hand bookstore (For the most part current OS/programming books are gold dust in such places.) you could try a library so you can try the books out to see if you find them a good reference source.
You'll want to learn about Unix/Linux, you could also learn about SQL and Database languages as well as a number of languages that are useful for batch processing. Perl, PHP, Python, C, SH, ASP, VBScript etc.
In all honesty, if you are stuck with finding out about a datagram perhaps you might think of something not so ..... well immense
