[comp.protocols.tcp-ip] sendmail hanging during SMTP session

doug@csd4.milw.wisc.edu (Doug Tiarks) (05/17/89)

Awhile back douglis@MINT.BERKELEY.EDU (Fred Douglis) reported a
problem with sendmail:

>>We're experiencing a problem sending mail to an internet host
>>(decwrl.dec.com) -- the symptom is that the mailer hangs for a long
>>time and then complains "reply: read error", apparently in the phase
>>just after it sends the body of the message.  I heard that about the
>>same time we started having this problem on Sprite, a small number of
>>Suns running SunOS 3.2 had the same problem, and I was told that
>>upgrading the kernel to 3.4 fixed the problem.  This is why I believe
>>the problem might have something to do with the TCP connection (since
>>just about everything at user level is the same, but the kernel is
>>new).

We are apparently seeing this problem from the other side.
Occasionally sendmail will go to sleep (waiting for input ?) during a
SMTP session with another host which is trying to deliver a message to
us.  This occurs at different stages (HELO, MAIL FROM, DATA) of the
SMTP session.  Sendmail eventually times out, but the host on the
other end apparently makes multiple tries during the timeout period
with the same result.  We're running v5.61 of sendmail with some fixes
from comp.bugs.4bsd under 4.3bsd-tahoe on a tahoe machine.

Anyone experiencing similar problems? Anyone know of a fix?



	Doug Tiarks
	UW-Milwaukee Computing Services Div.

	Internet: doug@csd4.milw.wisc.edu
	UUCP: {uwvax, uwmacc}!uwmcsd1!doug

--

	Doug Tiarks
	UW-Milwaukee Computing Services Div.

	Internet: doug@csd4.milw.wisc.edu
	UUCP: {uwvax, uwmacc}!uwmcsd1!doug

prue@VENERA.ISI.EDU (05/20/89)

Doug,

Jim Guyton at Rand described this same problem to me.  He
and I did some poking around and found that somewhere between here 
(Southern Calif.) and decwrl.dec.com, someone is clobbering packets larger 
than somewhere in the 1000-->1100 byte range.  We can ping all day with 
packets less than 1000 and get good reliablility but 1100 or more 
fails consistently.

Walt Prue

"Juan_Navarro.XOSMAR"@XEROX.COM (05/22/89)

Doug-
	When I was connecting our (XEROX's) TCP/IP gateway to Sun OS3.x (.2 or .5)
we were having the same problem. We fixed it by adding a E=\r\n at the end
of the Mtcp or Mether line in the sendmail.cf file.   I forget where this
is documented, but it works. You then need to kill and restart your
sendmail daemon.   Example:

	Mtcp, P=[IPC], F=mDFMueXL, S=14, R=14, A=IPC $h, E=\r\n
					or
	Mether, P=[IPC], F=mDFMueXL, S=11, R=21, A=IPC $h, E=\r\n

Good Luck.

//juan

dsmith@oregon.uoregon.edu (Dale Smith) (05/25/89)

While we are on the subject of mail, is anyone else having terrible
trouble delivering mail to the UK? I have have had consistent problems
for some time now (6 weeks?).  I ignored it for awhile, but this
discussion got me to poking about and it looks like someone between me
and nsfnet-relay.ac.uk is dropping packets longer than 500 bytes or so. 
Note that the packets are not getting fragmented, they are getting
dropped.

Now, I could crank down the MTU on my mail host, but I also use it for
all kinds of other things and that would kill me for performance.  Any
advice? Pointers? Anyone who has no trouble willing to act as a mail
forwarder for me for .uk mail?

At the end of this message is a traceroute between myself and
nsfnet-relay.ac.uk. (128.86.8.6).

Thanks,

Dale Smith
Asst Dir of Network Services	Internet: dsmith@oregon.uoregon.edu
University of Oregon		BITNET: dsmith@oregon.bitnet
Computing Center		UUCP: ...hp-pcd!uoregon!dsmith
Eugene, OR  97403-1212		Voice: (503)686-4394

----------------------------------------------------------------------
hogg# traceroute 128.86.8.6
traceroute to 128.86.8.6 (128.86.8.6), 30 hops max, 38 byte packets
 1  uo-gw.uoregon.edu (128.223.20.1)  20 ms  0 ms  20 ms
 2  192.33.18.10 (192.33.18.10)  500 ms  200 ms  180 ms
 3  192.31.215.10 (192.31.215.10)  560 ms  560 ms  380 ms
 4  129.101.101.10 (129.101.101.10)  1260 ms  580 ms  980 ms
 5  192.31.216.10 (192.31.216.10)  1000 ms  640 ms  660 ms
 6  192.35.180.3 (192.35.180.3)  700 ms  2500 ms  2020 ms
 7  129.140.70.14 (129.140.70.14)  400 ms  400 ms  460 ms
 8  129.140.71.6 (129.140.71.6)  440 ms  1200 ms  460 ms
 9  129.140.81.7 (129.140.81.7)  500 ms  740 ms  480 ms
10  129.140.72.17 (129.140.72.17)  560 ms  1100 ms  740 ms
11  * * *
12  ford-gateway.csc.org (128.121.54.73)  600 ms  680 ms  580 ms
13  128.121.54.78 (128.121.54.78)  580 ms  740 ms  540 ms
14  * * *
15  * * *
16  * * *
17  * * *
18  * * *
19  * * *
20  * * *
21  * * *
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * NSFNET-RELAY.AC.UK (128.86.8.6)  1600 ms  1660 ms