[OT] Re: TCP conection problems IBM VM -> FreeBSD
Ian Smith
smithi at nimnet.asn.au
Sun Mar 25 13:33:19 UTC 2007
On Sat, 24 Mar 2007 07:40:50 -0400 Richard reckons:
[..]
> Then I started thinking (always a fruitless endeavor), why would a *BSD
> based firewall/"IP stack" drop the corresponding SYN-ACK when it was
> activated? And that thought just fucking bugged me to no end. I could
> accept some crazy IBM "IP stack" not dealing with *BSD, but this was
> *BSD box to *BSD box on the return path that dropped the packet. Also,
> according to the original poster bang.swox.se has no problems
> communicating with other systems and he has no problems communicating to
> vm.se.lsoft.com.
I can't help with the Real Problem here, hence Subject change, but ..
[..]
> ** After looking through "Stevens TCP/IP Illustrated" I can find no
> reference to what sequence number a RST packet should have if a SYN-ACK
> precedes it. I'm unsure whether the RST should ACK the SYN + 1, as a
> SYN consumes a byte in normal operation, or return the ISN to the
> sending host. But as sending a RST in response to a SYN-ACK is not
> normal operation; such ambiguities would likely be left to the
> programmers discretion. In this case IBM not a stack derived from *BSD.
Secondly, the IBM TCP/IP stack and most userland network utilities were
declaredly BSD-derived at least through the '90s OS/2 times - and likely
much earlier, but I've not played with an IBM mainframe since '73 :)
But firstly, I wonder why you'd expect IBM to run 'some crazy' stack?
> this now opens a whole new box of worms?!?!?
Hopefully not ..
Cheers, Ian
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