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Old 08-04-2005, 05:13 PM   #1
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Default Strange IP Problems

We have had a problem the last couple of days here at work. We have a pretty average size LAN with about 5 switches on each floor(3 floors). We have 7 servers and a bunch of printers. About 150 users in the building. We noticed that 3 of our switches "stole" 3 of our users static IP addresses. We dont know how. DHCP is disabled on all servers as we do not use it. Everything is static here. Today one of our printers using a jet direct card had "stolen" another IP address. This printer is not set up to use an IP just MAC address. All of this just started to happen one day this week. It's the strangest thing. We have not found any viruses. We are pretty sure there is not a hacker trying to break in. Anyone have any suggestions on what we should be looking for or "who" we should be looking for??? HELP???

Oh also, we reset the switches and switched off the printer and that fixed or released those IP's?? Weird huh??
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Old 08-04-2005, 06:13 PM   #2
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Default Re: Strange IP Problems

I don't understand what you mean ... printers stealing ip addresses ? I doubt that can be possible, especially when they only identify systems using a MAC address ...
Also , what do you mean by stole ? As in they no longer exist or it is designated onto a different computer ?
Lol, i've never come across this problem ever
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Old 08-04-2005, 06:25 PM   #3
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Basically what happened today was a user got an error that said there was a tcpip conflict with his address. We tracked down where the conflict was coming from and somehow that specific tcpip address got assigned to the jet direct card on our printer here in the IT department. No one programmed it manually so we are wondering how this happened. The same thing happened with our switches yesterday. All of a sudden we had three people with the tcpip conflict message and we tracked it down to the switches..... This is the weirdest thing I have ever seen and I dont even know really where to start looking???
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Old 08-05-2005, 09:49 AM   #4
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Default Re: Strange IP Problems

check your event logs on the pc's and switches if they're managed switches. They might tell you something about ip addresses getting "re-assigned" or changed.
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Old 08-05-2005, 11:24 AM   #5
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Default Re: Strange IP Problems

Checked event logs and they are as unhelpful as usual. The switches are not managed, they are acting as dummy switches....basically jsut hubs. I am not an expert in routers or switches so any help on that would be good. I am looking into some monitoring software to see if it can detect it if it happens again but that's only where I'm at for now.
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Old 08-05-2005, 01:49 PM   #6
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Default Re: Strange IP Problems

i dont know try and assign a ip automatically, try going into the network connections and assign ip automatically.,
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Old 08-08-2005, 02:21 PM   #7
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Default Re: Strange IP Problems

I think I got it figured out, the switches are set to use BootP protocol as needed by default so I am trying to take that and disable it to see if that fixes the problem. BootP should only really be used if you are using DHCP. We will see how it goes. Thanks guys for the help.
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Old 09-21-2005, 11:35 AM   #8
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Default Re: Strange IP Problems

It sounds like you have a rogue dhcp server on your network
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