How can I find all DHCP servers on my network?

[Mr N8]

It seems that randomly computers on my network are getting a wi.rr.com (Road Runner) IP address issued to them when they boot up, and they should be getting a local address from my Windows 2003 server. The IP scheme is not the standard 192.168.... when they get the wi.rr.com address, either, so they have no connectivity to my domain.

Are there any utilities available to track down all computers that are acting as a DHCP server? I tried DHCP Find 1.2 and it was useless.

 

[spidey07]

find the IP address of the rogue dhcp server with ipconfig/all

that should get some information.

I've always just used features built in to network gear to prevent this from happening.

you could also try googling "detect rogue dhcp server"

 

[RebateMonger]

This is a major reason why I always set up my SBS Servers with dual NICs. When you put all the client computers downstream of the Server, it pretty much assures that all the client PCs will be forced to use the SBS Server as their Default Gateway, DHCP, and DNS Server. (Unless somebody sneaks a rogue router into the network). But, even then, SBS will detect the rogue DHCP server and complain about it. It avoids nuisances like this.

 

[Mr N8]

OK, now I feel dumb. Windows XP and 2003 Server have a tool called dhcploc.exe. That worked and I found that it was a wireless hub that someone brought from home and it still had a wi.rr.com address that it was using.

 

[nweaver]

time to spank that person who plugged that wireless AP in....


NO OUTSIDE CRAP PLUGGED IN PERIOD.

if you boss won't support that, then how can they expect you to keep an operational, secure, stable network.

 

[Mr N8]

We have a dorm area for our weekend staff, since we are a residential facility. They left it up so they can do some LAN gaming on the weekends. I already set them up with a 12 port switch, so that should more than meet their needs and not expose the network to needless risk and other stupid issues.

 

[nweaver]

Originally posted by: Mr N8
We have a dorm area for our weekend staff, since we are a residential facility. They left it up so they can do some LAN gaming on the weekends. I already set them up with a 12 port switch, so that should more than meet their needs and not expose the network to needless risk and other stupid issues.

exactly, you met their needs, so they should get the weewees smacked if they start futzing with it/adding wireless ap's etc. Unless you said "it's yours, go to town..."

but if you have it secured ,then it shouldn't have been passing packets into your secured network...