Tough problem! TCP reset issue

From: Andy Low (spider_at_bgp5.net_REMOVE_)
Date: 02/27/04 

Date: Fri, 27 Feb 2004 17:21:48 +0800

Hi,

Encounter some problem with my Server. To understand this require good
knowledge in TCP/IP Segment and 3-way handshakes

Here is the sequence of 3-way handshakes:

1) Host B --> Host A, src port:1878 dst port: 2000
[SYN] Seq=0 Ack=0 Win=16384 Len=0 MSS=1460

2) Host A --> Host B, src port: 2000, dst port: 1878
[SYN, ACK] Seq=0 Ack=1 Win=8192 Len=0 MSS=536

3) Host B --> Host A,
[TCP ZeroWindow] src port:1878 dst port:2000 [RST]
Seq=1 Ack=1576600895 Win=0 Len=0

More information:

1) Host B has not problem connecting to Host A all the while.

2) When Host C starts to download file from Host A, Host B gets connection
error

3) In packets debugging, it shows Host B send RST packets to Host A to
terminate the connection.

4) The TCP 3-way handshakes are not able to establish at all. SYN-ACK can
not be acknowledged by Host B.

Hope anyone can help,

Andy

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