Path: utzoo!utgpu!attcan!uunet!husc6!mailrus!purdue!decwrl!ucbvax!XX.LCS.MIT.EDU!CLIVE
From: CLIVE@XX.LCS.MIT.EDU (Clive B. Dawson)
Newsgroups: comp.protocols.tcp-ip
Subject: Network connectivity
Message-ID: <12443816123.48.CLIVE@XX.LCS.MIT.EDU>
Date: 4 Nov 88 09:23:32 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: clive%mcc.com@xx.lcs.mit.edu
Organization: The Internet
Lines: 23

MCC.COM (10.3.0.62) has unable to establish connections with a large
percentage of the Internet hosts during the past 24 hours.  I believe
much of this is caused by the fact that a lot of gateways have been
turned off to try and prevent the spread of the Unix virus that's been
going around.  Furthermore it looks like there's a lot of "one-way"
gateways out there.  OUr SMTP listener has had a lot of connections
hanging in SYN.SYN state and timing out, presumably because our SYN's
aren't making it back to the host who is trying to connect to us.

But I really got confused when I discovered that many of the hosts
I couldn't connect to were reachable from other hosts on the 10 net
(e.g. Score and XX).  If anybody can offer one or more explanations for
this, I would very much like to hear about it.  In particular,
what are the possible causes for a host being reachable from 10.a.b.c
but not from 10.x.y.z?  (Note that MCC.COM's "default,preferred"
address IS 10.3.0.62.)  The only explanation I can come up with 
is that something is messed up in the PSN routing tables, and that
this is a problem for the NOC.

Thanks,

Clive
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