[JDEV] UDP vs TCP

[Thomas Charron]

> >Finally, the last four companies I've worked at (read: EVERY company I've
> >worked at which had a computer) has had my computer situated behind a
proxy.
> >Most Universities now use proxies for all their computers (I know
University
> >of Florida even proxies the residence halls.) And I have a NAT proxy at
> >home, so that my notebook can access the internet through my linux
'server'.
> >How do these computers connect, if at all, on a UDP system?
> UDP sits behind a NAT proxy in same method TCP does :P. Actually thats how
> a lot of UDP applications work (mostly games) behind Proxies :P

  WHOAH there Nellie.  That will only work if you NAT *ALL* incoming UDB to
your internal network, which, well, it's a bad idea needless to say.  In the
case of TCP, the connection is initiated from inside machine, and a logical
session is created.  UDP, on the other hand, has no logical connection to
NAT.  In order to do UDP over NAT< you quite literally have to select, port
by port, what UDP packets will be forwarded to what internal machine.  A UDP
based system *CANNOT* function the same way behind a NAT firewall, or any
other sort of firewall, for that matter..