RE: testing for IP address space leakage in NAT systems

From: Jonah Kowall (jkowallat_private)
Date: Mon Jan 21 2002 - 09:54:27 PST

  • Next message: R. DuFresne: "Re: testing for IP address space leakage in NAT systems"

    I use a firewall filter, but you can throw up a filter to check for
    them.  I also check for outgoing and incoming leakage:
    
    On my Cisco I do this.
    
    Access lists:
    access-list 101 deny   ip mynetwork any log-input
    access-list 101 deny   ip 127.0.0.0 0.255.255.255 any log-input
    access-list 101 deny   ip 10.0.0.0 0.255.255.255 any log-input
    access-list 101 deny   ip 172.16.0.0 0.15.255.255 any log-input
    access-list 101 deny   ip 192.168.0.0 0.0.255.255 any log-input
    access-list 101 permit ip any any
    access-list 102 permit ip mynetwork any
    access-list 102 deny   ip any any log
    
    In wan interfaces:
     ip access-group 101 in
     ip access-group 102 out
    
    You can accomplish these filters with any firewall using similar rules.
    
    -----Original Message-----
    From: R P G [mailto:inittabat_private] 
    Sent: Monday, January 21, 2002 12:03 PM
    To: pen-testat_private
    Subject: testing for IP address space leakage in NAT systems
    
    
    I was wondering if anyone knows of a method to test a NAT system for
    address space leakage.
    
    Thanks.
    
    --Bob
    
    
    
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