[SamRvs]

Hi, I have just been hired on by an IT department with several hundred computers and several subnets, and my boss has asked me to provide him with a range of a dozen or so available IPs on our network. I've only worked with networks that use static IPs. Here, they use DHCP and static addresses both. How can I figure out which IPs are available?

[nexxev0]

You could use an IP scanner. There is a program i use every once in a while called Angry IP scanner. Its not as scary as the name makes it out to be :P. You put in a range for the IPs and it scans for active ones. The ones that are inactive show up as red.

[Mhouser]

Need an ipscan program.

I use Free IP Scanner http://www.eusing.com/ipscan/free_ip_scanner.htm
tell it a range to scan thru.
Example: Start 10.0.0.1 End 10.0.1.255
This would scan everything from 10.0.0. (1 thru 255) & 10.0.1.(1 thru 255)

Program reports IP, Workgroup Name, Host name, User, Mac Address

if reports N/S (no signal) usually available for Static address. Look for a group of these together.

[nexxev0]

Originally Posted by Mhouser

Need an ipscan program.

I use Free IP Scanner http://www.eusing.com/ipscan/free_ip_scanner.htm

I like that one too :P

[Mhouser]

For some reason my company firewall blocks all download sites for other IP Scanners except to the one I posted.

[SamRvs]

Thanks nexxev0 and Mhouser. I will download both of those immediately!

[nexxev0]

Originally Posted by Mhouser

For some reason my company firewall blocks all download sites for other IP Scanners except to the one I posted.

Eh IP scanning tools probably aren't exactly the best thing to let your fellow employees download :P

SamRvs:
No problem

[zx10guy]

In the environments I've worked, if you run any scanner or even the tools linked here, you will have a visit by the security office.

Anyways, if the environment is running DHCP, you can look on the DHCP server and see which IPs it has leased out. The scanner referenced to ping ranges of IPs only works if the device is turned on and answering.

[SamRvs]

That's a good point zx10guy. I had wondered about that. So, do I look under Scope > Reservations in DHCP?

[zx10guy]

No. It should be under some sort of log section. Sounds like you're using Windows server. It's been a while since I looked at a DHCP setup. The scope > reservations part is only if you want to set reservations (exclusions) within a pool of addresses in a scope.