Columbia Kermit/kermit.zip/newsgroups/misc.19950726-19950929/[e-mail]_Tue Sep 12 20:28:21 1995.msg

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From: [e-mail] (Dan Lanciani)
Newsgroups: comp.protocols.kermit.misc
Subject: Re: MS-KERMIT 3.14 hanging on idle TCP/IP connection?
Message-Id: <[e-mail]>
Date: 12 Sep 95 20:28:21 GMT
References: <42d2u9$[e-mail]> <433mrn$[e-mail]>
Organization: Internet
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Apparently-To: [e-mail]

In article <433mrn$[e-mail]>, [e-mail] (Seth Chaiklin) writes:
|
| In article <[e-mail]>, Dan Lanciani <[e-mail]> wrote:
|
| [stuff deleted about how a MSK machine would lose control of the
|  terminal output after about 10 minutes and the ARP cache on a Linux
| (1.2.8) machine would lose the hardware address of the MSK machine.  ]
|
| >You'd need a network trace to be sure, but this suggests that kermit
| >isn't responding to ARPs in its current state.
|
| I have traceroute and netstat (and maybe some others) on the Linux box.
| It was mentioned that this could be helpful, but I do not know what I should
| do or what I should look for.
|
| >There are at least two additional experiments that might shed light on
| >the situation.
| >First, while in the bad state, try to ping it from another machine that
| >has never been involved with the connection at all.  This should tell
| >you whether kermit is willing to respond to anybody's ARP at this point.
|
| I did try this, and the MSK machine responded to the ping, so there was no
| need to try the second test.

I forgot to ask whether this is another Linux box or something else.  If
something else, then it would still be good to try the ping-from-clean-
Linux-system test to see if such ARPs *ever* work.

| I also tried to ping from the Linux box, but there was no response.
| However, if I handloaded the Hardware address of the ethernet
| card on the MSK machine, then I could get a ping response.

In the absence of a trace (which would probably make everything completely
clear at this point), I can suggest one more drastic test.  Rather than adding
the ARP entry at this point, reboot the Linux machine.  This would (I hope)
determine whether something stateful on the Linux box prevented the ARP from
working.

| This was when I tried to ping from the Linux machine (with no response).
|
|I tried another experiment.  I logged in from the MSK machine, then immediately
| deleted the entry from the Linux ARP cache.  The output stopped, as other
| times.

Well, that's nice in a sense.  At least you can reproduce the problem on
demand without waiting for it to show up.

|It was still possible to telnet to other machines, but now it was
| impossible to telnet to the Linux machine, no error message or anything, just
| a return to the Kermit prompt.

Does it return immediately or take a while to time out?

| Finally, I hand-entered the hw address for the MSK machine, and now I have
| tried two or three times to let the MSK machine sit for for 30-60 minutes,
| and I have not been able to reproduce the problem.  It sounds like I
| should just try to load the addresses for these cards, maybe even as a
| cron job...but I would still like to try to understand what is going wrong.

I believe that a hand-entered address is not timed out (if Linux ARP is
typical).  That would explain why it didn't fail thereafter.

If you can point me at the version of kermit in question I can do some
tests myself...

                Dan Lanciani
                ddl@harvard.*