Well, for what ports to use (assuming you are talking about the TCP/UDP ports, not slang for "modules") then you might want to take a gander at your local services file. On a windows2k box it is typically in c:\winnt\system32\drivers\etc\services. In most *nix boxes, look for it as /etc/services. This file is a list of all defined ports (not all of them are necessarily in use, but these are the definitions that your box understands for those ports).  From this list, choose one that does not conflict with an existing service/program/daemon or whatnot.

Now, if on the other hand, you are looking for "modules" to use in your code, here are a few ideas that I recently used on a pet project of my own that is very similar.

1. XML:Simple is a fine quick start for XML handling.  Watch it though, it does no DTD or validity testing for you.
2. DBD::CSV and DBI to get the flat file into the program.
3. And then for your connections, you could use any one of a number of programs - all depending on exactly what you want to do in more specific detail.  If you are going to stay within the standard protocols (like FTP and HTTP) you night want to look into LWP::Simple or Net::FTP for a one stop solution and easy use.  If you need more specific port control, and perhaps more customization of the protocol is needed (a home-brew security, compression, or other modification) you could start out with IO:socket or for a more daemon/server style service you may want to look into adding in POE.

Hope this helps either way. Cheers! ..and happy turkey day!

*G*