[logs] Cisco PIX logs

From: Rainer Gerhards (rgerhardsat_private)
Date: Fri Jan 31 2003 - 09:59:42 PST

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    Hi all,
    
    I am banging my head for some time now, so I think it is time to ask for
    assistance... I am sure I am overlooking the obvious, but I simply don't
    see it ;)
    
    As an example, I have those two log lines in my PIX log (a little
    sanitized, though). According to Cisco's message description
    (http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_v53/syslo
    g/pixemsgs.htm#xtocid5) this tells me that the local machine at
    172.20.0.1 initiates a connection (via NAT) to 64.71.191.26. What makes
    me stumble are  the ports. In the message, I see my local machine using
    port 1071 and connecting to pt 5780 on the remote one. 
    
    ---
    2003-01-31,18:20:20,2003-01-31,18:20:20,172.19.0.1,20,6,Jan 31 2003
    17:12:41: %PIX-6-302005: Built UDP connection for faddr
    64.71.191.26/5780 gaddr 10.6.190.187/1071 laddr 172.20.0.1/1071
    
    
    2003-01-31,18:20:49,2003-01-31,18:20:49,172.19.0.1,20,6,Jan 31 2003
    17:13:10: %PIX-6-302006: Teardown UDP connection for faddr
    64.71.191.26/5780 gaddr 10.6.190.187/1071 laddr 172.20.0.1/1071
    ---
    
    So far, so good. When I look now at a packet capture taken on
    172.20.0.1, I see that the source port is indeed 1071 but the
    destination is 53 (DNS). The same holds true for the packet coming back.
    I did not (yet) take a packet capture at the Internet side of the
    firewall.
    
    Any explanation for this?
    
    Thanks,
    Rainer
    
    
    
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