[FOUND] connection reset after second syn-ack was sent (FreeBSD 7.0)

[Holger Kipp]

On Sun, Apr 20, 2008 at 01:49:27PM -0700, Jeremy Chadwick wrote:
> On Sun, Apr 20, 2008 at 08:23:28PM +0200, Holger Kipp wrote:
> > Well, still open questions here. Sight. 
> > Suggestions welcome. Ah, the initiating system is HP-UX...
> 
> I doubt this is the cause, but it's worth asking.
> 
> 1) Are you using pf(4) on the RELENG_7 box at all?

No, this is a vanilla 7.0-RELEASE installation with only lpd and
ntpd configured. Neither of pf, ipf or ipfw is used.

> 2) Have you tried turning off RFC1323 on the RELENG_7 box to see if
>    the TCP behaviour changes?  sysctl net.inet.tcp.rfc1323=0.

OK, will do. However, the described problem only happens when
the box is resending SYN-ACK after SYN was received and no answer
(ACK) was received after the first SYN-ACK. All other
connection requests from the same host to the same port (lpd)
work without problems. So currently this affects about 0.1 to 0.3
percent of all 3000 - 6000 print requests.

Regards,
Holger Kipp