Subject: [tcpm] TCP maintenance question

From: "Craig Buffinton" <[email-masked]>
Date: Thu, 1 Dec 2005 09:04:21 -0500

Please forgive me if this question is not appropriate for this forum.

Should TCP accept connections from source port zero? 

As best I can determine port zero is valid and there are no prohibitions
on its use, although iana does list it as reserved.

The reason for the question is that I maintain a TCP stack that asserts
that the source port in a received syn packet must be non-zero. 

A defect in a TCP proxy device caused the inadvertent use of port zero.
It seems to me that the right action is to accept the connection. 

If port zero is invalid then should a syn with source port zero be
silently ignored or reset?

Thanks in advance 

Craig Buffinton

_______________________________________________
tcpm mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/tcpm

---

From: Joe Touch <[email-masked]>
Date: Thu, 01 Dec 2005 07:46:09 -0800

> on its use, although iana does list it as reserved.

IANA reservations apply to destination ports, not source ports.

> that the source port in a received syn packet must be non-zero.

Given the above, in the absence of any other evidence (which I could not
find in 793 or 1122), that seems like a bug.

> silently ignored or reset?

If the port turns out to be invalid, it should result in an ICMP port
unreachable reply, IMO.

JOe