Re: Strange open ports on windows machines

From: Thomas Lopatic (tlat_private)
Date: Sat Oct 23 1999 - 08:48:30 PDT

  • Next message: Russ: "RE: Strange open ports on windows machines"

    Hi there,
    
    > 12345   filtered    tcp       NetBus
    > 31337   open        udp       BackOrifice
    
    "filtered" means that there was a timeout when nmap tried to connect to
    port 12345. Hence, this port is probably filtered at some firewall
    between you and the computer you scanned.
    
    The same is probably true for port 31337. UDP scanning works as follows.
    nmap sends a UDP packet to a port and then waits for an ICMP port
    unreachable message, which indicates, that there is not service
    listening at that particular port. If it does not get an ICMP port
    unreachable message, nmap will tell you that there is a service that
    listens at the port.
    
    If the UDP message is filtered at an intermediate firewall, then the
    computer will never see that UDP packet and you will never get an ICMP
    port unreachable - and nmap thinks that there is some listening service.
    
    I think that this is the most plausible explanation. A packet filter
    that protects the network that you have scanned.
    
    Have a nice day
    -Thomas
    
    -- 
    Thomas Lopatic, data protect AG (tlat_private)
    



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