Subject: Re: A simple TCP/socket/port question
To: None <,>
From: Olaf Seibert <>
List: current-users
Date: 07/05/1996 12:24:49
Pete Bentley <> wrote:
> Just to be pedantic, it's a 6-tuple made up of <port, addr, protocol>
> for both the source and the destination (OK, so protocol is always the
> same for both).  Otherwise it would be impossible for the kernel to
> distinguish between (eg) TCP and UDP exchanges using the same port
> numbers. 

To be even more pedantic ;-) I don't think it generalises in this way,
for two reasons: 1) UDP has no connections (and that is what we were
talking about), and 2) some protocols don't have port numbers at all
(such as ICMP, the protocol that goes ping...)

The decision on "where does this packet belong" is made in a decision
tree, where first TCP and UDP are split up and each protocol decides for
itself (if it needs to) what port and/or connection the packet belongs to.

> Pete.
___ Olaf 'Rhialto' Seibert      D787B44DFC896063 4CBB95A5BD1DAA96 
\X/ Ceci n'est pas un Magritte