01-30-2003 08:38 AM - edited 02-21-2020 12:19 PM
Hi,
I have a very strange situation. I have configured a VPN between two networks but a TCP application that should run through the tunnel is failing. The remote end is sending RST to the SYN. Below is the output of the network dump. I tried to reduce the MTU but with no success (the application runs through Cisco VPN client using dialup).
any clues what might be wrong? Thanx in advance.
----------------------------------------
Internet Protocol, Src Addr: 10.160.196.130 (10.160.196.130), Dst Addr: 57.206.114.200 (57.206.114.200)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 48
Identification: 0x013e
Flags: 0x04
.1.. = Don't fragment: Set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: TCP (0x06)
Header checksum: 0x7dd1 (correct)
Source: 10.160.196.130 (10.160.196.130)
Destination: 57.206.114.200 (57.206.114.200)
Transmission Control Protocol, Src Port: 1067 (1067), Dst Port: 5010 (5010), Seq: 148829501, Ack: 0, Len: 0
Source port: 1067 (1067)
Destination port: 5010 (5010)
Sequence number: 148829501
Header length: 28 bytes
Flags: 0x0002 (SYN)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...0 .... = Acknowledgment: Not set
.... 0... = Push: Not set
.... .0.. = Reset: Not set
.... ..1. = Syn: Set
.... ...0 = Fin: Not set
Window size: 64512
Checksum: 0xf58c (correct)
Options: (8 bytes)
Maximum segment size: 1460 bytes
NOP
NOP
SACK permitted
Internet Protocol, Src Addr: 57.206.114.200 (57.206.114.200), Dst Addr: 10.160.196.130 (10.160.196.130)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 48
Identification: 0x013e
Flags: 0x04
.1.. = Don't fragment: Set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 126
Protocol: TCP (0x06)
Header checksum: 0x7fd1 (correct)
Source: 57.206.114.200 (57.206.114.200)
Destination: 10.160.196.130 (10.160.196.130)
Transmission Control Protocol, Src Port: 5010 (5010), Dst Port: 1067 (1067), Seq: 0, Ack: 148829502, Len: 0
Source port: 5010 (5010)
Destination port: 1067 (1067)
Sequence number: 0
Acknowledgement number: 148829502
Header length: 28 bytes
Flags: 0x0014 (RST, ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 0... = Push: Not set
.... .1.. = Reset: Set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 64512
Checksum: 0xf579 (correct)
Options: (8 bytes)
Maximum segment size: 1460 bytes
NOP
NOP
SACK permitted
02-05-2003 09:44 AM
I remember having come across a similar problem some time ago. Just as is the case here, the remote end was sending a RST to a SYN. The root in that case turned out to be the presence of CBAC. It seems that CBAC and a client initiated HTTP session don't go together. If you have CBAC configured, try removing the same and see if the setup works normally.
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