Subject: Re: Sendmail delivery funny
To: None <,>
From: Julian Coleman <>
List: current-users
Date: 11/05/2000 17:01:34
> 	please provide the folloing information.
> 	- what do you mean by "TTL 0"?

tcpdump shows :

  18:30:56.735349 > S [tcp sum ok] 1004049898:1004049898(0) win 16384 <mss 1484> [ttl 0] (id 3455)

> 	- can you tell us which domain is the destination? (so that we can see
> 	  the MX records for the destionation).

This mail was going to  I have :


in my, so I only see AAAA (no reply) and A lookups for the relay.
Also, this happens to every mail message that goes out.

> 	- show us the result of "netstat -an" during the delayed connection.
> 	  (otherwise, you are not sure if the first trial is to IPv6
> 	  destination or not)

Well, I wasn't 100% sure, but ktrace of sendmail showed :

  10567 sendmail CALL  socket(0x18,0x1,0)
  10567 sendmail RET   socket 6
  10567 sendmail CALL  __sigprocmask14(0x1,0,0x82b88)
  10567 sendmail RET   __sigprocmask14 0
  10567 sendmail CALL  __sigaltstack14(0,0xefffa950)
  10567 sendmail RET   __sigaltstack14 0
  10567 sendmail CALL  connect(0x6,0xefffaa78,0x1c)
  10567 sendmail RET   connect -1 errno 60 Connection timed out
  10567 sendmail CALL  close(0x6)

for each failed connection and domain 0x18 is INET6.  As soon as it does :

  10567 sendmail CALL  socket(0x2,0x1,0)

the mail gets sent.

`netstat -an` shows (lots of output but I assumed you're interested in) :

  tcp6       0      0  ::ffff: ::ffff:    SYN_SENT

Also, `fstat` shows :

  root     sendmail   11032    8* internet6 stream tcp f0429600 [::ffff:]:49344 <-> [::ffff:]:25

> 	if you do not have IPv6 default route, even if sendmail attempts to
> 	connect to IPv6 destination, it will fail right away and there should
> 	be no problem.

`netstat -rn` shows the following IPv6 routes on ppp0 :

  fe80::%ppp0/64                link#3                    UC          0        0   1524  ppp0
  fe80::a00:20ff:fe09:6caf%ppp0 ::1                       UH          0        0  33228  lo0
  ff02::%ppp0/32                link#3                    UC          0        0   1524  ppp0



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