26sec problems

Kelly Scroggins kelly at cliffhanger.com
Wed Apr 6 14:05:40 CEST 2005

The first thing that comes to mind is the rules
defining the traffic that will be encrypted, has
to 'match', or rather, be mirrored.

In other words ...

  FWA will permit traffic from host-A to host-Z
  FWB will permit traffic from host-Z to host-A

You may already have them configured this way, but
it's the first thing I'd check.


Quoting Petr Titera <P.Titera at century.cz>:
           I have a problem with 26sec tunnel setup. My network configuration 
        looks as follows:
             +-------+                                      +-------+
         eth1|       |eth2                              eth0|       |eth1
         ----|  FWA  |------------IPSEC VPN-----------------|  FWB  |----
             |       |                                      |       |
             +-------+                                      +-------+
        Both firewalls have kernel version 2.6.10.
        I have ADSL modem connected on eth0 and eth2 at FWA site. I've setted up 
        VPN tunel between both firewals and there fun begins.
           I can ping the computers in internal networks from both direction.
           Users from unternal network of FWB can connect to computers in 
        internal network of FWA without any problem, but
        users from FWA network cannot conect at all.
           When I trace traffic from FWA network to FWB network I see strange 
        things happen. SYN packets are transfered, but when real communication 
        starts I see this:
           on FWA:eth1 I see packets to other computer
           on FWA:eth2 I see packets going to tunnel and packets going from 
        tunnel without a change
           on FWB:eth0 I see packets from tunnel without a change
           on FWB:eth1 I see communication in both direction
        BUT on FWA:eth1 I see packets from other direction as going from another 
        port than I have connected:
        This is communication as I see it on FWA:eth1 port. Note change from 
        http port to tcpmux port.
        09:23:46.372945 IP > S 
        3072626488:3072626488(0) win 5840 <mss 1460,sackOK,timestamp 3092376420 
        0,nop,wscale 0>
        09:23:46.485595 IP > S 
        2915082851:2915082851(0) ack 3072626489 win 65535 <mss 1460,nop,wscale 
        0,nop,nop,timestamp 0 0,nop,nop,sackOK>
        09:23:46.485715 IP > . ack 1 
        win 5840 <nop,nop,timestamp 3092376478 0>
        09:23:51.963654 IP > F 1:1(0) 
        ack 1 win 5840 <nop,nop,timestamp 3092379283 0>
        09:23:52.065913 IP > . ack 
        3072626490 win 65535 <nop,nop,timestamp 10752655 3092379283>
        09:23:52.066028 IP > R 
        3072626490:3072626490(0) win 0
        09:23:52.171022 IP > F 0:0(0) 
        ack 1 win 65535 <nop,nop,timestamp 10752656 3092379283>
        Any idea what is wrong?
        Petr Titera


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