Finding available IP addresses on network?
Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: Finding available IP addresses on network?

  1. #1
    It's a gas!
    Join Date
    Jul 2002
    Posts
    699

    Finding available IP addresses on network?

    How can i find out what IP addresses are available on a windows network?

    Probably something simple but i cant think how to do this...

    Help appreciated.

    r3b007

  2. #2
    Senior Member
    Join Date
    Jan 2002
    Posts
    1,207
    As long as all your hosts are set up to respond to pings, you could just write a script to ping every IP. The ones that don't respond are available.

    If you run a DHCP server, then it will know which ones are available.

    I'm guessing however, that you have static IPs. If this is the case, you can ping them all, but beware the machines which aren't turned on

    The most robust way of doing it is to go around manually cataloguing them. However it will be a pain in the arse (esp. the laptop that the company director has taken on holiday with him)

  3. #3
    It's a gas!
    Join Date
    Jul 2002
    Posts
    699
    Yeah, all the machines have static IP's so i guess i was wrong about it being something simple

    Thanks for the reply

  4. #4
    Leftie Linux Lover the_JinX's Avatar
    Join Date
    Nov 2001
    Location
    Beverwijk Netherlands
    Posts
    2,535
    the easiest way to scan for (online) ip adresses:

    say you want to scan all ip's starting with 192.168

    nmap -sP 192.168.*.*

    but then you'll have to know that they are all on !!
    ASCII stupid question, get a stupid ANSI.
    When in Russia, pet a PETSCII.

    Get your ass over to SLAYRadio the best station for C64 Remixes !

  5. #5
    It's a gas!
    Join Date
    Jul 2002
    Posts
    699
    Its a windows server so nmap is no good!

  6. #6
    Junior Member
    Join Date
    Jul 2003
    Posts
    19
    If you are running a WINS/DDNS service on the Windows network you can get the IP information from this database.
    Ping sweeps will also do the trick, but is very noizy on large networks and like said before will only catch active NICs. Very easy to assign duplicate IPs that way.

  7. #7
    Junior Member
    Join Date
    Jul 2003
    Posts
    23

    Re

    Apologise if me being daft first post and all..but just try a scanning tool like this one www.lookatlan.com slong as you know your starting ip just let her go and shell come back with a list of empty/unused

  8. #8
    It's a gas!
    Join Date
    Jul 2002
    Posts
    699
    Thanks for all the useful replies guys.
    Ill try out some of the suggestions.

    Cheers

  9. #9
    The Doctor Und3ertak3r's Avatar
    Join Date
    Apr 2002
    Posts
    2,744
    Not daft Shaggy100..

    Languard is another tool .. and basicly as the_JinX's instructed.. set it to scann ie 192.168.0.0 - 192.168.0.255
    b4 you start:..just be sure you won't get shot by the admin for doing a scann
    that is for any prog or script you could use to "scann" for available IP's..

    BTW.. I am too lazy to check.. But isn't there a Win version of nmap?

    Cheers
    "Consumer technology now exceeds the average persons ability to comprehend how to use it..give up hope of them being able to understand how it works." - Me http://www.cybercrypt.co.nr

  10. #10
    Senior Member
    Join Date
    Jan 2002
    Posts
    1,207
    There is a Windows version of nmap, it will work fine. You can ping scan your network (which just pings the boxes), and easily tell which ones are up.

    I'd still recommend a physical audit (provided there aren't too many boxes), as it will catch anything not turned on.

    You can't rely on WINS or DDNS to give you the IP of every device on the network, because it's not guaranteed that all hosts will be in it. For instance, some Windows boxes might not be part of the domain, or other devices (usually switches, routers and printers) will be using IP addresses.

    As far as being shot by the admin is concerned, I was assuming that you *were* the admin. I was certainly in a similar situation a few years ago, and had to catalogue all the static IPs and hunt out a few rogue devices.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

 Security News

     Patches

       Security Trends

         How-To

           Buying Guides