Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!pasteur!ucbvax!umiacs.UMD.EDU!steve From: steve@umiacs.UMD.EDU (Steven D. Miller) Newsgroups: comp.protocols.tcp-ip Subject: Re: Interlan drops a byte? Message-ID: <8808241123.AA18269@fnord.umiacs.UMD.EDU> Date: 24 Aug 88 11:23:31 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 179 The problem here is not in your Interlan card; I've had the same problem with my Sun-3/60. I did a packet spy once, and it seems that under certain circumstances, expo seems to send the FIN with a sequence number that is one too low. The spy I made of the problem is enclosed below, so that others more knowledgeable in the ways of TCP may check my reasoning. I think expo is running vanilla SunOS 3.4 TCP, but I'm by no means certain of that... -Steve Spoken: Steve Miller Domain: steve@mimsy.umd.edu UUCP: uunet!mimsy!steve Phone: +1-301-454-1808 USPS: UMIACS, Univ. of Maryland, College Park, MD 20742 pktnum 2483, timestamp 577459160 sec 410000 usec, len 54 Ethernet level: dst host 08:00:20:00:6f:74, src host 02:07:01:00:8a:17, type 800 IP header: version 4, header len 5, service 0, len 228, id 95c5, off 0, ttl 18, protocol 6, sum e, src 121e00d4, dst 80087803 TCP header: source port 14, dst port 477, 1d52972,108d4e01 data off 5, flags=10 window 1000, sum 45a2, urgent 0 TCP data length 512 (0x200) bytes pktnum 2484, timestamp 577459160 sec 410000 usec, len 54 Ethernet level: dst host 02:07:01:00:8a:17, src host 08:00:20:00:6f:74, type 800 IP header: version 4, header len 5, service 0, len 28, id b6f9, off 0, ttl 1e, protocol 6, sum dad9, src 80087803, dst 121e00d4 TCP header: source port 477, dst port 14, 108d4e01,1d52f72 data off 5, flags=10 window 2000, sum f076, urgent 0 TCP data length 0 (0x0) bytes pktnum 2485, timestamp 577459160 sec 530000 usec, len 54 Ethernet level: dst host 08:00:20:00:6f:74, src host 02:07:01:00:8a:17, type 800 IP header: version 4, header len 5, service 0, len 228, id 95c6, off 0, ttl 18, protocol 6, sum d, src 121e00d4, dst 80087803 TCP header: source port 14, dst port 477, 1d52b72,108d4e01 data off 5, flags=10 window 1000, sum 81b0, urgent 0 TCP data length 512 (0x200) bytes pktnum 2486, timestamp 577459160 sec 530000 usec, len 54 Ethernet level: dst host 02:07:01:00:8a:17, src host 08:00:20:00:6f:74, type 800 IP header: version 4, header len 5, service 0, len 28, id b6fa, off 0, ttl 1e, protocol 6, sum dad8, src 80087803, dst 121e00d4 TCP header: source port 477, dst port 14, 108d4e01,1d52f72 data off 5, flags=10 window 2000, sum f076, urgent 0 TCP data length 0 (0x0) bytes pktnum 2487, timestamp 577459160 sec 810000 usec, len 54 Ethernet level: dst host 08:00:20:00:6f:74, src host 02:07:01:00:8a:17, type 800 IP header: version 4, header len 5, service 0, len 228, id 95c7, off 0, ttl 18, protocol 6, sum c, src 121e00d4, dst 80087803 TCP header: source port 14, dst port 477, 1d52d72,108d4e01 data off 5, flags=10 window 1000, sum 96d3, urgent 0 TCP data length 512 (0x200) bytes [expo sent 512 bytes after seq 1d52d72 ] pktnum 2488, timestamp 577459160 sec 810000 usec, len 54 Ethernet level: dst host 02:07:01:00:8a:17, src host 08:00:20:00:6f:74, type 800 IP header: version 4, header len 5, service 0, len 28, id b6fb, off 0, ttl 1e, protocol 6, sum dad7, src 80087803, dst 121e00d4 TCP header: source port 477, dst port 14, 108d4e01,1d52f72 data off 5, flags=10 window 2000, sum f076, urgent 0 TCP data length 0 (0x0) bytes [fnord acks that] pktnum 2489, timestamp 577459160 sec 930000 usec, len 54 Ethernet level: dst host 08:00:20:00:6f:74, src host 02:07:01:00:8a:17, type 800 IP header: version 4, header len 5, service 0, len 1b8, id 95c8, off 0, ttl 18, protocol 6, sum 7b, src 121e00d4, dst 80087803 TCP header: source port 14, dst port 477, 1d52f71,108d4e01 data off 5, flags=19 window 1000, sum 2a8, urgent 0 TCP data length 400 (0x190) bytes [expo, whose sequence number was 1d52f72, now sends a FIN with the sequence number one too low.] pktnum 2490, timestamp 577459160 sec 930000 usec, len 54 Ethernet level: dst host 02:07:01:00:8a:17, src host 08:00:20:00:6f:74, type 800 IP header: version 4, header len 5, service 0, len 28, id b6fc, off 0, ttl 1e, protocol 6, sum dad6, src 80087803, dst 121e00d4 TCP header: source port 477, dst port 14, 108d4e01,1d53102 data off 5, flags=10 window 1e71, sum f075, urgent 0 TCP data length 0 (0x0) bytes [fnord acks that] pktnum 2491, timestamp 577459161 sec 70000 usec, len 54 Ethernet level: dst host 02:07:01:00:8a:17, src host 08:00:20:00:6f:74, type 800 IP header: version 4, header len 5, service 0, len 28, id b6fe, off 0, ttl 1e, protocol 6, sum dad4, src 80087803, dst 121e00d4 TCP header: source port 477, dst port 14, 108d4e01,1d53102 data off 5, flags=11 window 2000, sum eee5, urgent 0 TCP data length 0 (0x0) bytes [fnord sends its fin, with seq # 108d4e02] pktnum 2492, timestamp 577459161 sec 230000 usec, len 54 Ethernet level: dst host 08:00:20:00:6f:74, src host 02:07:01:00:8a:17, type 800 IP header: version 4, header len 5, service 0, len 28, id 95cb, off 0, ttl 18, protocol 6, sum 208, src 121e00d4, dst 80087803 TCP header: source port 14, dst port 477, 1d53102,108d4e01 data off 5, flags=11 window 1000, sum fee5, urgent 0 TCP data length 0 (0x0) bytes pktnum 2493, timestamp 577459161 sec 250000 usec, len 54 Ethernet level: dst host 02:07:01:00:8a:17, src host 08:00:20:00:6f:74, type 800 IP header: version 4, header len 5, service 0, len 28, id b6ff, off 0, ttl 1e, protocol 6, sum dad3, src 80087803, dst 121e00d4 TCP header: source port 477, dst port 14, 108d4e01,1d53103 data off 5, flags=11 window 2000, sum eee4, urgent 0 TCP data length 0 (0x0) bytes pktnum 2494, timestamp 577459161 sec 270000 usec, len 54 Ethernet level: dst host 08:00:20:00:6f:74, src host 02:07:01:00:8a:17, type 800 IP header: version 4, header len 5, service 0, len 28, id 95cc, off 0, ttl 18, protocol 6, sum 207, src 121e00d4, dst 80087803 TCP header: source port 14, dst port 477, 1d53102,108d4e02 data off 5, flags=11 window 1000, sum fee4, urgent 0 TCP data length 0 (0x0) bytes pktnum 2495, timestamp 577459161 sec 410000 usec, len 54 Ethernet level: dst host 08:00:20:00:6f:74, src host 02:07:01:00:8a:17, type 800 IP header: version 4, header len 5, service 0, len 28, id 95cd, off 0, ttl 18, protocol 6, sum 206, src 121e00d4, dst 80087803 TCP header: source port 14, dst port 477, 1d53103,108d4e02 data off 5, flags=10 window 1000, sum fee4, urgent 0 TCP data length 0 (0x0) bytes pktnum 2496, timestamp 577459161 sec 410000 usec, len 54 Ethernet level: dst host 02:07:01:00:8a:17, src host 08:00:20:00:6f:74, type 800 IP header: version 4, header len 5, service 0, len 28, id b700, off 0, ttl 1e, protocol 6, sum dad2, src 80087803, dst 121e00d4 TCP header: source port 477, dst port 14, 108d4e02,0 data off 5, flags=4 window 0, sum 41c9, urgent 0 TCP data length 0 (0x0) bytes