BUG: Win NT TCP/IP Security filters does not get enforced

From: Stefan Norberg (stnorat_private)
Date: Fri Oct 08 1999 - 10:04:13 PDT

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    Regardless of settings in the TCP/IP Security filters any IP protocol is
    accepted.
    
    TCP/IP security configuration example:
    
    Permit all TCP ports, Permit all UDP ports, Permit only IP protocols: 6
    
    The easiest way to prove it's broken is to configure it to only allow
    IP-protocol 6 (TCP) and then ping (ICMP) the host. ICMP being IP protocol 1
    of course.
    
    Another simple way to test this is to use Weld Pond's NT-port of Hobbit's
    netcat  (http://www.l0pht.com/~weld/netcat/ ) to set up a udp-listener on a
    host that is supposed to block udp. Then use netcat on another host to send
    it a nice message.
    
    CLIENT:
    C:\>nc -u server 5000
    tcp/ip security is broken :)
    
    SERVER:
    C:\>nc -u -l -p 5000
    tcp/ip security is broken :)
    
    windump: listening on \Device\Packet_El90x1
    18:49:06.731069 CLIENT.3533 > SERVER.5000: udp 29
    
    Seems pretty broken to us...
    
    Tested on NT4.0 SP5 (both w. no hotfixes and all hotfixes)
    
    Regards,
    
    
    Stefan Norberg (stnorat_private , http://people.hp.se/stnor)
    Daryl Banttari (darylat_private)
    



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