Date: Sat, 2 Nov 1996 15:23:06 -1000 (HST) From: kent@lono.nosc.mil (Kent K. Kuriyama) To: freebsd-bugs@freebsd.org Cc: kent@lono.nosc.mil (Kent K. Kuriyama), u651rc@emh.cpf.navy.mil, kobash@lono.nosc.mil (Sidney H. Kobashigawa) Subject: Illegal options in TCP header? Message-ID: <9611030123.AA16199@lono.nosc.mil>
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I am running FreeBSD version 2.1.0.
I believe that FreeBSD is inserting illegal options in the TCP header
packets which it sends out during the session negotiation phase.
Shown below is a sniffer trace of the packets sent out by the
FreeBSD box to 198.22.146.10. Notice that it sends an unknown option
3 on the TCP header.
This causes the host at 198.22.146.10 to refuse the connection (frame
2). Now granted the host at 198.22.146.10 (system type unknown) is
the first one that refuses a connection from our FreeBSD's systems
but the sniffer trace also indicates that the FreeBSD system is sending
TCP headers with illegal options. I believe that 1 is the only valid
option defined.
As a basis for comparision of what other unix systems send I have
included a sucessfully session establishment from an Interactive
Unix box to the same host (frames 3 through 5).
Any insight into this problem would be greatly appreciated. Thank
you.
Kent Kuriyama
kent@nosc.mil
- - - - - - - - - - - - - - - - Frame 1 - - - - - - - - - - - - - - - - -
SUMMARY Delta T Destination Source Summary
M 1 [198.22.146.10] freebsd.cpf.n.. TCP D=25 S=1534 SYN SEQ=743819265 LEN=0 WIN=16384
TCP: ----- TCP header -----
TCP:
TCP: Source port = 1534
TCP: Destination port = 25 (SMTP)
TCP: Initial sequence number = 743819265
TCP: Data offset = 48 bytes
TCP: Flags = 02
TCP: ..0. .... = (No urgent pointer)
TCP: ...0 .... = (No acknowledgment)
TCP: .... 0... = (No push)
TCP: .... .0.. = (No reset)
TCP: .... ..1. = SYN
TCP: .... ...0 = (No FIN)
TCP: Window = 16384
TCP: Checksum = 80EE (correct)
TCP:
TCP: Options follow
TCP: Maximum segment size = 512
TCP: No-op
TCP: Unknown option 3
TCP: 22 byte(s) of header padding
TCP:
ADDR HEX ASCII
0000 00 00 0C F0 C1 04 00 00 4A 10 13 D4 08 00 45 10 ........J.....E.
0010 00 44 30 B4 00 00 40 06 73 66 C0 65 BE 03 C6 16 .D0...@.sf.e....
0020 92 0A 05 FE 00 19 2C 55 C8 01 00 00 00 00 C0 02 ......,U........
0030 40 00 80 EE 00 00 02 04 02 00 01 03 03 00 01 01 @...............
0040 08 0A 00 10 4D AC 00 00 00 00 01 01 0C 06 00 00 ....M...........
0050 42 0A B.
- - - - - - - - - - - - - - - - Frame 2 - - - - - - - - - - - - - - - - -
SUMMARY Delta T Destination Source Summary
2 0.3329 freebsd.cpf.n.. [198.22.146.10] TCP D=1534 S=25 RST ACK=743819266 WIN=4380
TCP: ----- TCP header -----
TCP:
TCP: Source port = 25 (SMTP)
TCP: Destination port = 1534
TCP: Sequence number = 0
TCP: Acknowledgment number = 743819266
Sniffer Network Analyzer data from 1-Nov-96 at 20:32:38, file C:\CAPTURE\SMTP.ENC, Page 2
TCP: Data offset = 20 bytes
TCP: Flags = 14
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 0... = (No push)
TCP: .... .1.. = Reset
TCP: .... ..0. = (No SYN)
TCP: .... ...0 = (No FIN)
TCP: Window = 4380
TCP: Checksum = CDBB (correct)
TCP: No TCP options
TCP:
ADDR HEX ASCII
0000 00 00 4A 10 13 D4 00 00 0C F0 C1 04 08 00 45 00 ..J...........E.
0010 00 28 65 5D 00 00 35 06 49 E9 C6 16 92 0A C0 65 .(e]..5.I......e
0020 BE 03 00 19 05 FE 00 00 00 00 2C 55 C8 02 50 14 ..........,U..P.
0030 11 1C CD BB 00 00 00 00 00 00 00 00 ............
- - - - - - - - - - - - - - - - Frame 3 - - - - - - - - - - - - - - - - -
SUMMARY Delta T Destination Source Summary
3 31.2447 [198.22.146.10] unix.cpf.navy.. TCP D=25 S=1029 SYN SEQ=659147265 LEN=0 WIN=4096
TCP: ----- TCP header -----
TCP:
TCP: Source port = 1029
TCP: Destination port = 25 (SMTP)
TCP: Initial sequence number = 659147265
TCP: Data offset = 20 bytes
TCP: Flags = 02
TCP: ..0. .... = (No urgent pointer)
TCP: ...0 .... = (No acknowledgment)
TCP: .... 0... = (No push)
TCP: .... .0.. = (No reset)
TCP: .... ..1. = SYN
TCP: .... ...0 = (No FIN)
TCP: Window = 4096
TCP: Checksum = D3E9 (correct)
TCP: No TCP options
TCP:
ADDR HEX ASCII
0000 00 00 0C F0 C1 04 00 00 4A 10 1A 6E 08 00 45 00 ........J..n..E.
0010 00 28 2A 66 00 00 40 06 79 DA C0 65 BE 09 C6 16 .(*f..@.y..e....
0020 92 0A 04 05 00 19 27 49 CA 01 00 00 00 00 50 02 ......'I......P.
0030 10 00 D3 E9 00 00 05 79 6F 6B 31 30 .......yok10
- - - - - - - - - - - - - - - - Frame 4 - - - - - - - - - - - - - - - - -
Sniffer Network Analyzer data from 1-Nov-96 at 20:32:38, file C:\CAPTURE\SMTP.ENC, Page 3
SUMMARY Delta T Destination Source Summary
4 0.4323 unix.cpf.navy.. [198.22.146.10] TCP D=1029 S=25 SYN ACK=659147266 SEQ=4980388 LEN=0 WIN=0
TCP: ----- TCP header -----
TCP:
TCP: Source port = 25 (SMTP)
TCP: Destination port = 1029
TCP: Initial sequence number = 4980388
TCP: Acknowledgment number = 659147266
TCP: Data offset = 24 bytes
TCP: Flags = 12
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 0... = (No push)
TCP: .... .0.. = (No reset)
TCP: .... ..1. = SYN
TCP: .... ...0 = (No FIN)
TCP: Window = 0
TCP: Checksum = D0E0 (correct)
TCP:
TCP: Options follow
TCP: Maximum segment size = 512
TCP:
ADDR HEX ASCII
0000 00 00 4A 10 1A 6E 00 00 0C F0 C1 04 08 00 45 00 ..J..n........E.
0010 00 2C 65 67 00 00 35 06 49 D5 C6 16 92 0A C0 65 .,eg..5.I......e
0020 BE 09 00 19 04 05 00 4B FE A4 27 49 CA 02 60 12 .......K..'I..`.
0030 00 00 D0 E0 00 00 02 04 02 00 ED AF ............
- - - - - - - - - - - - - - - - Frame 5 - - - - - - - - - - - - - - - - -
SUMMARY Delta T Destination Source Summary
5 0.0019 [198.22.146.10] unix.cpf.navy.. TCP D=25 S=1029 ACK=4980389 WIN=4096
TCP: ----- TCP header -----
TCP:
TCP: Source port = 1029
TCP: Destination port = 25 (SMTP)
TCP: Sequence number = 659147266
TCP: Acknowledgment number = 4980389
TCP: Data offset = 20 bytes
TCP: Flags = 10
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 0... = (No push)
TCP: .... .0.. = (No reset)
TCP: .... ..0. = (No SYN)
TCP: .... ...0 = (No FIN)
Sniffer Network Analyzer data from 1-Nov-96 at 20:32:38, file C:\CAPTURE\SMTP.ENC, Page 4
TCP: Window = 4096
TCP: Checksum = D4E9 (correct)
TCP: No TCP options
TCP:
ADDR HEX ASCII
0000 00 00 0C F0 C1 04 00 00 4A 10 1A 6E 08 00 45 00 ........J..n..E.
0010 00 28 2A 68 00 00 40 06 79 D8 C0 65 BE 09 C6 16 .(*h..@.y..e....
0020 92 0A 04 05 00 19 27 49 CA 02 00 4B FE A5 50 10 ......'I...K..P.
0030 10 00 D4 E9 00 00 54 72 79 69 6E 67 ......Trying
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