Re: Packets from 255.255.255.255(80) (was: Packet from port 80 with spoofed microsoft.com ip)

From: Frederic Harster (f.harsterat_private)
Date: Mon Feb 03 2003 - 07:56:23 PST

  • Next message: Neil Dickey: "Speedera Ping, was "Packets from 255.255.255.255(80), etc.""

    Hugo van der Kooij wrote:
    
    >>Let's say that a router is configured (with ACLs) to deny packets from
    >>255.255.255.255 (that's why I noticed them). Then it sends back an "ICMP
    >>unreachable", doesn't it?
    >>These ICMP packets try to travel to... 255.255.255.255! Would'n it cause
    >>a multiplying?
    >>I know that a router/firewall may be configured to _not_ send "ICMP
    >>unreachables" but default is to send them.
    >>    
    >>
    >
    >The default behaviour for filtering must be to DROP the packets. This is 
    >standard in all known firewalls and should be considered common knowledge.
    >
    >Some call this stealth mode.
    >  
    >
    Although I  _could_  agree as far as a firewalls are concerned, I don't 
    when it comes to routers.
    Blocking/droping any ICMP packet usually turns into a real nightmare 
    when you've to perform troubleshooting on a wide network.
    
    my 0,02... and common pratice.
    Fred
    
    >  
    >
    
    
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