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Date:      Wed, 9 Jun 1999 22:20:15 -0400 (EDT)
From:      "Crist J. Clark" <cjc@cc942873-a.ewndsr1.nj.home.com>
To:        dwhite@resnet.uoregon.edu (Doug White)
Cc:        cjclark@home.com, freebsd-questions@FreeBSD.ORG
Subject:   Re: SSH X Forwarding
Message-ID:  <199906100220.WAA08126@cc942873-a.ewndsr1.nj.home.com>
In-Reply-To: <Pine.BSF.4.03.9906091703400.3005-100000@resnet.uoregon.edu> from Doug White at "Jun 9, 99 05:04:52 pm"

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Doug White wrote,
> On Wed, 9 Jun 1999, Crist J. Clark wrote:

> > The first time this occured, the machine in question had 'xlock'
> > running, and I wondered if this was preventing X connections (which
> > does not seem like proper behavior, but this is one of the few things
> > about this machine that is different from the others I connect to
> > successfully). However, now, with no xlock, there are the same errors.
> > 
> > The sshd server in question is running on 3.1-STABLE and was built
> > from the ports.
> 
> Perhaps a tcpdump is in order?  Maybe the remote is blocking X requests
> from non-local hosts.

Well, the machine I was having problems with earlier _is_ local (on
the same wire, I assume that is what you mean). But I did the dump
just now from a remote machine... I'm not sure what exactly to make of
it. The machines talk a bit when the connetion is made. Then, I give
an 'xterm' command, and tcpdump shows,

22:06:00.155784 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: P 756:776(20) ack 1352 win 17520 (DF) [tos 0x10]
22:06:00.334199 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1352:1372(20) ack 776 win 17520 (DF) [tos 0x10]
22:06:00.380118 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: . ack 1372 win 17520 (DF) [tos 0x10]
22:06:00.750710 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: P 776:796(20) ack 1372 win 17520 (DF) [tos 0x10]
22:06:00.975884 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1372:1392(20) ack 796 win 17520 (DF) [tos 0x10]
22:06:00.980135 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: . ack 1392 win 17520 (DF) [tos 0x10]
22:06:01.022457 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: P 796:816(20) ack 1392 win 17520 (DF) [tos 0x10]
22:06:01.130711 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1392:1412(20) ack 816 win 17520 (DF) [tos 0x10]
22:06:01.180135 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: . ack 1412 win 17520 (DF) [tos 0x10]
22:06:01.182652 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: P 816:836(20) ack 1412 win 17520 (DF) [tos 0x10]
22:06:01.237078 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: P 836:856(20) ack 1412 win 17520 (DF) [tos 0x10]
22:06:01.299060 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1412:1432(20) ack 856 win 17520 (DF) [tos 0x10]
22:06:01.314166 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: P 856:876(20) ack 1432 win 17520 (DF) [tos 0x10]
22:06:01.323674 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1432:1452(20) ack 856 win 17520 (DF) [tos 0x10]
22:06:01.380128 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: . ack 1452 win 17520 (DF) [tos 0x10]
22:06:01.439768 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1452:1472(20) ack 876 win 17520 (DF) [tos 0x10]
22:06:01.580124 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: . ack 1472 win 17520 (DF) [tos 0x10]
22:06:02.000272 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: P 876:896(20) ack 1472 win 17520 (DF) [tos 0x10]
22:06:02.114737 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1472:1492(20) ack 896 win 17520 (DF) [tos 0x10]
22:06:02.180143 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: . ack 1492 win 17520 (DF) [tos 0x10]
22:07:17.116835 pc222.mydomain.com.ssh > mypc.myhome.com.1010: P 1492:1632(140) ack 896 win 17520 (DF) [tos 0x10]
22:07:17.184970 mypc.myhome.com.1010 > pc222.mydomain.com.ssh: . ack 1632 win 17520 (DF) [tos 0x10]

Where I believe that final exchange is pc222 passing me the failure
message.

I'm not exactly sure how I could be more detailed in a tcpdump of a
ssh session. After all, everything deeper than what I have shown is
encrypted, no?

Any more suggestions of what to check would be appreciated. Or a
diagnosis of the above that I am missing would be even better.
-- 
Crist J. Clark                           cjclark@home.com


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