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#1 XP_2600

XP_2600

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Posted 01 November 2012 - 10:27

I would like to identify all dhcp servers in my network, is there any scanners can scan the network for DHCP service ?


#2 Haggis

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Posted 01 November 2012 - 10:29

Surely if its your network you should know where all the DHCP servers are?

a little more info on what your attempting to do might help here

#3 +giantsnyy

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Posted 01 November 2012 - 10:43

Sometimes I've seen rogue DHCP servers pop up.

For example Avaya is great at this. I've had an IP office system just start handing out IP's right after a power failure... just turned dhcp service on. Drove me nuts for two days because it was handing out the same IP's as my normal DHCP server! I used a combination of overlook fing and portqry in windows server.

#4 OP XP_2600

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Posted 01 November 2012 - 11:15

I am the network admin yes and its my network, i just added a DSL cheap router and another access point seems they both offering DHCP so i get conflicts.

Sometimes I've seen rogue DHCP servers pop up.

For example Avaya is great at this. I've had an IP office system just start handing out IP's right after a power failure... just turned dhcp service on. Drove me nuts for two days because it was handing out the same IP's as my normal DHCP server! I used a combination of overlook fing and portqry in windows server.

Exactly thats what i face now!

#5 Haggis

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Posted 01 November 2012 - 11:39

Sorry i don't see what the confusion is about your problem

if you added a cheap dsl router and an AP and both are offering DHCP then turn them off on the admin console

If i am missing something here i apologise but it seems extremely easy to fix from what you have said

#6 OP XP_2600

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Posted 01 November 2012 - 11:42

Haggis, Excuse me, this is what i was trying to find, and now i found!

http://www.softpedia...DHCP-Find.shtml


#7 +BudMan

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Posted 01 November 2012 - 12:01

"i just added a DSL cheap router and another access point seems they both offering DHCP so i get conflicts."

I'm with Haggis here - turn one of them off or both of them if you have a server providing dns, problem solved. Now if you were sure you turned them both off and where still getting problems then there might be a rouge.

But finding a rouge dhcp is pretty simple - you don't really need a scanner ;) Sniff the traffic and you will get the mac of the dhcp server sending out the offers and acks both of which will be broadcast 255.255.255.255 so any box on the network should see this traffic.

Now the tricky part can be having the smart switches to be able to figure out what port that mac is connected too.