Re: Ambiguities in TCP/IP - firewall bypassing

From: David Wagner (dawat_private)
Date: Fri Oct 18 2002 - 17:18:50 PDT

  • Next message: Aaron Hopkins: "Re: Ambiguities in TCP/IP - firewall bypassing"

    Paul Starzetz  wrote:
    >We believe that the flaws we have detected have a big impact on 
    >design of firewalls and packet filters since an improper implementation 
    >can easily lead to serious security problems.
    
    Is there any reason to expect that such improper implementation
    would be common?
    
    As far as I know, the common case is packet filters that look at
    only the ACK and SYN bits.  A typical configuration: All incoming
    packets with the ACK bit set are allowed, as are all outgoing packets.
    The anomalies you found don't seem to pose any problems for such a
    style of configuration.
    
    Are you aware of any common configurations that are at risk?
    



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