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Thread: scanning PC's behind a router or firewall

  1. #1
    Junior Member
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    Default scanning PC's behind a router or firewall

    is it possible to scan PC's behind a NAT router or firewall from internet

    if so how can i do that

  2. #2

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    is it possible to scan PC's behind a NAT router or firewall from internet
    It's possible but depends on many variables.

    - Does the router or firewall forward any ports to internal clients?
    - Is the firewall stateful?

    These are just 2 off the top of my head.

    If I were you, I would investigate how to use hping, tcptraceroute, udp tracerouting, and also some of the more advanced features of nmap.

    Try googling for a technique known as "Firewalking". It is a bit old, but the paper provides a decent overview of how to deduce ACL's and firewall rules using various tracerouting techniques.

    Good Luck...

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  4. #4
    Super Moderator lupin's Avatar
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    Default

    Quote Originally Posted by ammadeyy View Post
    is it possible to scan PC's behind a NAT router or firewall from internet

    if so how can i do that
    The method that will get the most accurate results is to get a machine that is directly attached to that network to do the scanning for you. So exploit a client on the network or exploit the router/firewall itself and use the access you have obtained to perform the scanning.

    Otherwise you will have to rely on a misconfigured firewall or NAT device to perform the scanning, and the results will be hit and miss.
    Capitalisation is important. It's the difference between "Helping your brother Jack off a horse" and "Helping your brother jack off a horse".

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  5. #5
    Senior Member BigMac's Avatar
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    Default

    it depends on how the router is configured. if there are 4 computers behind a router, each computer is hosting a server and the router is configured properly

    router configuration ip 123.87.43.99
    port 80 forward to 192.168.1.2:computer1
    port 21 forward to 192.168.1.3:computer2
    port 25 forward to 192.168.1.4:computer3
    etc...

    if you were to scan the ip 123.87.43.99 you would see those 3 ports open... it all depends on the network configuration...

    in advance, sorry for not reading the hole thread

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