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Date: Mon, 21 Apr 1997 05:39:41 -0500
From: Tim Tsai <tim@futuresouth.com>
To: questions@freebsd.org, isp@freebsd.org
Subject: Help interpreting this tcpdump log
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  I am enclosing a tcpdump session that demonstrate a problem we're
seeing.  ts is a Livingston terminal server and mail is a FreeBSD 2.2.1R
machine.  The problem is that "telnet mail 25" from the terminal server
will show the initial sendmail login banner, but nothing works after
that.  It seems that this problem is only showing up if we go through
the terminal server.  Any ideas?  MTU is set to 1500 on both machines
and they're on the same ethernet segment.

  Thanks,

  Tim

Result of:
"ts> telnet mail 25<cr>"
"HELP<cr>"
no response after this.
05:22:41.144757 ts.1062 > mail.smtp: S 127:127(0) win 2048
05:22:41.144909 mail.smtp > ts.1062: S 1673748096:1673748096(0) ack 128 win 16384 <mss 1460> (DF)
05:22:41.145669 ts.1062 > mail.smtp: . ack 1 win 2048
05:22:41.157537 mail.smtp > ts.1062: P 1:94(93) ack 1 win 16384 (DF)
05:22:41.158462 ts.1062 > mail.smtp: . ack 94 win 2048
05:22:41.199733 ts.1062 > mail.smtp: P 1:7(6) ack 94 win 2048
05:22:41.307065 mail.smtp > ts.1062: . ack 7 win 16384 (DF)
05:22:42.078261 ts.1062 > mail.smtp: P 7:8(1) ack 94 win 2048
05:22:42.107059 mail.smtp > ts.1062: . ack 8 win 16384 (DF)
05:22:42.188094 ts.1062 > mail.smtp: P 8:9(1) ack 94 win 2048
05:22:42.297938 ts.1062 > mail.smtp: P 9:10(1) ack 94 win 2048
05:22:42.307060 mail.smtp > ts.1062: . ack 10 win 16384 (DF)
05:22:42.407825 ts.1062 > mail.smtp: P 10:11(1) ack 94 win 2048
05:22:42.507069 mail.smtp > ts.1062: . ack 11 win 16384 (DF)
05:22:42.737394 ts.1062 > mail.smtp: P 11:12(1) ack 94 win 2048
05:22:42.907061 mail.smtp > ts.1062: . ack 12 win 16384 (DF)
05:22:44.440164 ts.1062 > mail.smtp: F 12:12(0) ack 94 win 2048
05:22:44.440286 mail.smtp > ts.1062: . ack 13 win 16384 (DF)
05:22:44.440880 mail.smtp > ts.1062: P 94:120(26) ack 13 win 16384 (DF)
05:22:44.441368 mail.smtp > ts.1062: F 120:120(0) ack 13 win 16384 (DF)
05:22:44.441763 ts.1062 > mail.smtp: . ack 120 win 2048
05:22:44.442204 ts.1062 > mail.smtp: . ack 121 win 2048