RE: [PEN-TEST] Detecting the presence of a firewall

From: Frank Knobbe (FKnobbeat_private)
Date: Tue May 15 2001 - 14:37:03 PDT

  • Next message: Nate Lawson: "Windump/Winpcap ported to gcc (cygwin)"

    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA1
    
    > -----Original Message-----
    > From: railwayclubposseat_private
    > [mailto:railwayclubposseat_private]
    > Sent: Tuesday, May 15, 2001 10:49 AM
    > 
    > You get the same results if the default Checkpoint ports are 
    > closed. You 
    > still need to find one or two open ports, but they don't have 
    > to be on the 
    > firewall itself. The giveaway is in how the headers are 
    > rewritten for one-
    > to-many NAT. 
    
    
    Uhm... I'm confused. I assume you mean ports of statically natted
    machines. I connect from the Internet through the FW-1 to a host
    behind behind it. That is a one-to-one NAT. What is rewritten in the
    headers that would identify the screening fw as a FW-1 machine? I
    mean IP addresses are obviously changed. What other header
    information (i.e. flags, options) are changed in the packet coming
    form the host? I understand that I should expect a certain option set
    in a response packet (depending on OS and my request packet), I
    understand the process, I'm not question this. Just would like to
    know what is reset/changed in the TCP or UDP packet. (Let's ignore
    ICMP). Point me to an article or FAQ please.
    
    Regards,
    Frank
    
    -----BEGIN PGP SIGNATURE-----
    Version: PGP Personal Privacy 6.5.8
    Comment: PGP or S/MIME encrypted email preferred.
    
    iQA/AwUBOwGhf5ytSsEygtEFEQIvsACgoTtMFV/4RxlUGwGFKpzMVkGXkDMAmgMa
    jgNg9+TBLNivSvLJZFdJHhex
    =K0ok
    -----END PGP SIGNATURE-----
    



    This archive was generated by hypermail 2b30 : Tue May 15 2001 - 22:02:07 PDT