----- ���� ���� -----
���� ���: Choe, Hyun-ho <[EMAIL PROTECTED]>
�� ���: <[EMAIL PROTECTED]>
���� ��¥: 1999�� 11�� 22�� ������ ���� 11:00
����: [Q] Some sites can't be connected in Linux...
Hi, Everyone...
I have some trouble with linux networking...
My linux box cannot connect to some websites, but windows can...
I use cable modem and my ISP made new configuration recently...
after that time, I got above problem...
I use kernel 2.2.12 and Alzza-Linux 6.0 (Korean RedHat clone) and I tested
with lynx.
I checked packets with sniffit and I got following results...
(I edit packet dump for comment....)
Supported Network device found. (eth0)
Sniffit.0.3.7 Beta is up and running.... (linux.sarang.net)
// This is Connection Request...(my linux box sent) : (SYN:On, Seq:X)
Packet ID (from_IP.port-to_IP.port): 210.180.119.40.1213-210.122.59.30.80
45 00 00 3C
AF 8A 40 00
40 06 33 BC
D2 B4 77 28
D2 7A 3B 1E
--------------------------------------------------------------- IP Header
04 BD 00 50
E9 9D 42 DE : Sequence Number - E99D42DE
00 00 00 00
A0 02 7D 78 : Syncronize - On
A2 ED 00 00
02 04 05 B4 : Max Seg Size = 05B4(RFC793)
04 02 : Selective Acknowledgement Permitted(RFC2018)
08 0A : Timestamp Option(RFC2018)
01 B6 9C EC : Timestamp Value
00 00 00 00
01 : NOP(RFC793)
03 03 00 : Windows Scaling Factor = 2^0(RFC1323)
--------------------------------------------------------------- TCP Header
// And this is Connection Acknowledgement from target host...(ACK:On,
SYN:On, Ack:X+1, Seq:Y)
Packet ID (from_IP.port-to_IP.port): 210.122.59.30.80-210.180.119.40.1213
45 00 00 3C
1B A3 40 00
FB 06 0C A3
D2 7A 3B 1E
D2 B4 77 28
--------------------------------------------------------------- IP Header
00 50 04 BD
24 CA 82 6E : Sequence Number - 24CA826E
E9 9D 42 DF : Acknowledgement Number - E99D42DF
A0 12 FE 88 : Acknowledgement - On, Syncronize - On
5A 0D 00 00
01 01 : NOP, NOP(RFC793)
08 0A : Timestamp Option(RFC2018)
07 2A 1C 5D : Timestamp Value
01 B6 00 EC : Timestamp Echo Reply
01 : NOP(RFC793)
03 03 00 : Windows Scaling Factor = 2^0(RFC1323)
02 04 05 B4 : Max Seg Size = 05B4(RFC793)
--------------------------------------------------------------- TCP Header
// And next... my linux box should send Connection Establish to target
host...(ACK:On, Ack:Y+1)
// but send Connection Request again like following...
// Resend Connection Request...(SYN:On, Seq:X)
Packet ID (from_IP.port-to_IP.port): 210.180.119.40.1213-210.122.59.30.80
45 00 00 3C
AF 8C 40 00
40 06 33 BA
D2 B4 77 28
D2 7A 3B 1E
--------------------------------------------------------------- IP Header
04 BD 00 50
E9 9D 42 DE : Sequence Number - E99D42DE
00 00 00 00
A0 02 7D 78 : Syncronize - On
A1 C1 00 00
02 04 05 B4
04 02 08 0A
01 B6 9E 18
00 00 00 00
01 03 03 00
--------------------------------------------------------------- TCP Header
So, connection cannot be established and no further communication was
made....
I noticed received packet has different order of TCP Option List from
original packet
and suspect this may be the problem....
1. Why my linux does not recognize connection ACK ?
2. What response is defined in linux when TCP Option List order was changed
?
(I cannot find any statement about this situation in RFC)
3. What machine changed TCP Option list order...?
In my test environment, client machine is linux, and target server is
also linux, and Apache 1.3.9.
(I don't know server's kernel version exactly... probably 2.3.x , I
guess...
target server change that order, or some router/gateway does...
I think this problem occurres only at port 80, because same server works
well in FTP connection....
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