tcp and udp

[mandreko]

can someone explain the difference? or what each do? i'm familiar with tcp/ip but i've never really dealt with udp... but a program i have needs the 1505 udp port open... and i have no idea how to do that... since it's a firewall, and the port needs to forward to my second computer (192.168.1.2)

[Nailz]

TCP looks for confirmation that the packet has been sent, whereas UDP does not care.

UDP is more like a Broadcasting protocol. Think of if more like a radio. It's just sending packets out. Real Audio uses UDP to broadcast over the internet. TCP is more like a telephone (?) where it's looking for a someone on the other end to pick up the call.

------------------
$> cd /pub
$> more beer

[This message has been edited by Nailz (edited 13 December 2000).]

[FoBoT]

nice analogy, Nailz, and good explaination

UDP is also refered to "connectionless", this refers to the "broadcast" nature, ie the packets go out, the sender has no idea if they get received or are lost
http://www.technotronic.com/tcpudp.html

[This message has been edited by FoBoT (edited 13 December 2000).]

[mandreko]

ok, then do udp and tcp share the same ports? like are port 21 on tcp the same as 21 on udp, they just don't send the same way?

[Stuka]

That's sorta right - both tcp and udp use the same ports (even simultaneously if you like). As far as my limited knowledge goes, a port being 'open' essentially means that there is a socket (either tcp or udp) listening on that port.

[This message has been edited by Stuka (edited 13 December 2000).]

[FoBoT]

funkproxy 1505/tcp Funk Software, Inc.
funkproxy 1505/udp Funk Software, Inc.

see
http://www.technotronic.com/tcpudp.html

1505 is either, just open the port the way you are used to with tcp/ip ports, should work just fine

[mandreko]

ok, well how would i open the tcp and udp ports 1505 on my linux machine? and how would i make them forward to my second machine?