Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!rutgers!bellcore-2!envy!karn
From: karn@envy.bellcore.com (Phil R. Karn)
Newsgroups: comp.sys.hp
Subject: Re: IBM/HP-UX FTP session hangs on PORT command
Message-ID: <1990Jul19.185513.15656@bellcore-2.bellcore.com>
Date: 19 Jul 90 18:55:13 GMT
References: <277@camdev.UUCP>
Sender: usenet@bellcore-2.bellcore.com (Poster of News)
Reply-To: karn@thumper.bellcore.com
Distribution: na
Organization: Packet Communications Research Group (Bellcore)
Lines: 18


In article <277@camdev.UUCP>, sscott@camdev.UUCP (Steve Scott) writes:
> Steve, we have seen a problem for a long time where FTP sessions from IBM
> TCPIP to an HP node would fail when the FTP application issued a PORT
command.
> By testing the PORT command manually, I find that HP nodes are not accepting
> port arguments where the first decimal portion of the port address is 3 or
> less (ie PORT 192,25,80,1,3,200). I found nothing in the RFC indicating a
> limit or restriction.

It's possible that the problem is not due to the hosts at all, but
rather to an administrative restriction in the routers between them.
Some sites block incoming TCP packets addressed to ports below 1024 as
a heuristic to restrict externally originated TCP connections, because
the Internet convention is to have servers listening on low numbered
ports.

Phil