On Sat, Mar 27, 2004 at 04:20:44AM -0000, James Craig Burley wrote:
> >No. That's one less port he can use to connect to you (on any given
> >destination port). He can still use the same source port to connect to
> >others. TCP connections are four-tuples.
>
> Should I not trust O'Reilly's "TCP/IP Network Administration", by
> Craig Hunt, Second Edition, page 46, where it says, among other things
> consistent with this,
>
> It is the pair of port numbers, source and destination, that
> uniquely identifies each network connection.
>
> or do you think it is just simplifying things for the benefit of its
> audience?
Read that again. The pair of port numbers, source and destination
(at the TCP layer)... plus the pair of IP addresses (at the IP layer).
> Further, my Fedora Core 1 system does not appear to reuse dynamic port
> numbers when I open telnet sessions to distinct hosts.
>
> But I could be wrong.
Many systems will use originating port numbers in sequence; more recently,
for security reasons, they may use them in random order. However the
fact remains that TCP/IP connections are uniquely identified by the
four-tuple [source IP, source port, dest IP, dest port]. The limitation
on the number of open connections is therefore generally available RAM
for the networking structures in the OS kernel (or application, in the
case of an application crafting its own packets.)
Hope that helps,
*** Xanni ***
--
mailto:[EMAIL PROTECTED] Andrew Pam
http://www.xanadu.com.au/ Chief Scientist, Xanadu
http://www.glasswings.com.au/ Technology Manager, Glass Wings
http://www.sericyb.com.au/ Manager, Serious Cybernetics
