Re: DENY x REJECT

From: Fyodor (fyodorat_private)
Date: Thu Oct 04 2001 - 15:33:03 PDT

  • Next message: Andrew Simmons: "Re: Blind penetration testing"

    On Wed, Oct 03, 2001 at 12:52:51PM -0300, Rosenau wrote:
    >
    > Nmap seems to report boths cases simply as "filtered". Actually, both cases
    > are filtered, but when you receive a ICMP, you can be sure that the port is
    > really filtered. If you do not receive nothing, the port could be filtered,
    > or packets could have been lost...
    
    For what it is worth, Nmap always retries ports that do not respond.
    It only marks them "filtered" after multiple probes fail to elicit any
    response.  If lost packets are detected (for example if Nmap receives
    a response to the second probe but not the first one), then the number
    of retries is increased dramatically.  Thus it is unlikely that an
    open port will be mislabeled "filtered" because of a few dropped
    packets.
    
    That being said, I agree that knowing the source of ICMP error
    messages is handy and I am hoping to add that to the XML output format
    at some point.  If you want it really soon, you are welcome to make
    the (relatively simple) changes yourself.  That is the beauty of open
    source!  If you send me your patches, I will consider them for the
    core Nmap tree so that everyone can benefit from them.
    
    Cheers,
    Fyodor
    http://www.insecure.org/
    
    
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