Re: Scan of TCP 552-554

From: Chris Shepherd (chrissat_private)
Date: Fri Aug 01 2003 - 05:25:08 PDT

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    Quoting Rodrigo Barbosa <rodrigobat_private>:
    > > In this case, it may make sense to keep your traps on a honeypot box. I'm
    > > having a bit of a difficult time understanding exactly what you mean
    > > by 'hit my traps faster, so I can react faster'. React how? What would your
    > > reaction to a port scan be? If you cite an example, I'll probably have a
    > >much clearer idea about what kinds of traps you're talking about. :)
    >
    > Errr, filter the address or network on the border router ? That is one.
    > Contact the admin of the network about the scan is another.
    
    Why take that action for a port scan? You're going to be a very busy admin if
    you do all that just for a simple port scan. Those things are unimportant, but
    might be useful if logged, or better yet, dropped. :) There's nothing wrong
    with a port scan in and of itself, it is just a simple check to see which
    services you have listening.
    
    A policy of having a live person react to a port scan is a little farther than
    I'd be willing to go ever, which is why I simply have my firewall refuse to
    talk on any port that doesn't have a service running. Closed ports are not a
    security risk, nor are portscans. The security risks come into play on the
    services you already are running. The biggest reason why someone in your shoes
    might want to consider using DROP vs REJECT is that it offers a higher delay in
    accessing those services. Regardless of your firewall, if you have a service in
    place, that is far more likely to become the subject of attack, and wanting to
    conceal those services from port scanning is a more intelligent approach (IMO)
    than wanting to try and conceal the firewall's existence. The point of
    intrusion shouldn't be at the firewall if it is properly configured, but
    rather, the hosts behind it that are by necessity running servers (Apache or
    IIS for example).
    
    I'm not really sure you gain anything by making your firewall pretend to be a
    live host, other than speed up target acquisition for an unfriendly host.
    
    --
    Chris Shepherd
    
    
    
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