i'm not an expert in this stuff but this is what i would do

write a server app. that routes descriptors, then it would be easy to get host/IP number cause of all the pongs going through the server,

then you'll need an algorithm to update the host/IP number on the web site

this stuff i descriped will have to be done on your server so client side languages are no good (but they may have other uses)

html is the only one of those languages i know, but i would recommend C/C++ or java cause they seems easyer then perl (i studied a tiny bit of each)

http://www.limewire.com/index.jsp has a lot of good dev. resource

if you need any more info. just let me know