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Message 1 of 10
Anonymous
572 Views, 9 Replies

DHCP madness!

Greetings all, I have a fun one.

First,
Win 2k
One nic
Static IP (always has been)

When I upgraded our license server to the new Flexlm (from 2002 to
2004, our server suddenly, according to two different logs, started
requesting *2* IP addresses via DHCP! The DHCP server is happily
handing them out but the license server is keeping it's proper static
address. The real problem is that we are using dynamic dns updates so
suddenly our server has 3 dns entries. This is obviously a problem.

It's a really cranium tickler, I am plum out of ideas right now
9 REPLIES 9
Message 2 of 10
Anonymous
in reply to: Anonymous

"rich" wrote in message
news:ED634CA66ED1E61F1D284A68BAC0BD56@in.WebX.maYIadrTaRb...
> Greetings all, I have a fun one.
>
> First,
> Win 2k
> One nic
> Static IP (always has been)
>
> When I upgraded our license server to the new Flexlm (from 2002 to
> 2004, our server suddenly, according to two different logs, started
> requesting *2* IP addresses via DHCP! The DHCP server is happily
> handing them out but the license server is keeping it's proper static
> address. The real problem is that we are using dynamic dns updates so
> suddenly our server has 3 dns entries. This is obviously a problem.
>
> It's a really cranium tickler, I am plum out of ideas right now
>
I doubt your server is the one requesting the IP. Could it be another
machine with the same name?

Mike
Message 3 of 10
Anonymous
in reply to: Anonymous


> I doubt your server is the one requesting the IP. Could it be another
> machine with the same name?
>
> Mike
>
>

As far as I knew, you can't do that. Computer names have to be unique
withing the same network. Depending on the DHCP server you are using
(OS wise) it should record the MAC address of the requesting machine.
Check the logs to see if it is indeed the License server that is making
the request.

It's possible that the Flexlm server software installed some network
stuff that is requesting a DHCP address. I would check the settings on
the server to see if that's the case. But this is purely speculation,
since I am unfamiliar with the Flexlm software.

Cheers,
CMF
Message 4 of 10
Anonymous
in reply to: Anonymous

The only way I can think of that DHCP will hand out three IP addresses is if
there were network interfaces to assign them to. At a Command prompt (DOS)
type IPCONFIG /ALL and see how many adapters are defined on that server.
Also look at the descriptions of the adapters, some may be logical adapters
and the description should provide you a clue as to their source. What
happens if you ping these phantom IP addresses?

I do not know of anything in the FLEXlm license management system that could
trigger this behavior.

--
Jerry Milana,
Autodesk Professional Services

"Chris Ferris" wrote in message
news:74B6AF923BE487ADAE72799B9E86DCA4@in.WebX.maYIadrTaRb...
>
> > I doubt your server is the one requesting the IP. Could it be another
> > machine with the same name?
> >
> > Mike
> >
> >
>
> As far as I knew, you can't do that. Computer names have to be unique
> withing the same network. Depending on the DHCP server you are using
> (OS wise) it should record the MAC address of the requesting machine.
> Check the logs to see if it is indeed the License server that is making
> the request.
>
> It's possible that the Flexlm server software installed some network
> stuff that is requesting a DHCP address. I would check the settings on
> the server to see if that's the case. But this is purely speculation,
> since I am unfamiliar with the Flexlm software.
>
> Cheers,
> CMF
>
Message 5 of 10
Anonymous
in reply to: Anonymous

Mike Donahue wrote:
> "rich" wrote in message
> news:ED634CA66ED1E61F1D284A68BAC0BD56@in.WebX.maYIadrTaRb...
>
>>Greetings all, I have a fun one.
>>
>>First,
>>Win 2k
>>One nic
>>Static IP (always has been)
>>
>>When I upgraded our license server to the new Flexlm (from 2002 to
>>2004, our server suddenly, according to two different logs, started
>>requesting *2* IP addresses via DHCP! The DHCP server is happily
>>handing them out but the license server is keeping it's proper static
>>address. The real problem is that we are using dynamic dns updates so
>>suddenly our server has 3 dns entries. This is obviously a problem.
>>
>>It's a really cranium tickler, I am plum out of ideas right now
>>
>
> I doubt your server is the one requesting the IP. Could it be another
> machine with the same name?
>
> Mike
>
>
It absolutly is unless another machine is spoofing the mac address
Message 6 of 10
Anonymous
in reply to: Anonymous

None of that seems to apply. There is only one adapter defined in "My
Network Places". Ipconfig lists what it is supposed to list (one adapter
at the static address). Nothing exists at the rouge addresses.
Yesterday we tried disabling the dhcp client service on the license
server to no avail.

The only strange thing that I've found is an "Incomming Connections"
item in "MY Network Places" but it seems to be part of another licnece
managment software that uses a parallel port key. I disabled all tcp/ip
functions related to it.

sigh, it's the problem that won't go away. 4 sets of eyes have examined
it so far.

jerry milana wrote:

> The only way I can think of that DHCP will hand out three IP addresses is if
> there were network interfaces to assign them to. At a Command prompt (DOS)
> type IPCONFIG /ALL and see how many adapters are defined on that server.
> Also look at the descriptions of the adapters, some may be logical adapters
> and the description should provide you a clue as to their source. What
> happens if you ping these phantom IP addresses?
>
> I do not know of anything in the FLEXlm license management system that could
> trigger this behavior.
>
> --
> Jerry Milana,
> Autodesk Professional Services
>
> "Chris Ferris" wrote in message
> news:74B6AF923BE487ADAE72799B9E86DCA4@in.WebX.maYIadrTaRb...
>
>>
>>
>>>I doubt your server is the one requesting the IP. Could it be another
>>>machine with the same name?
>>>
>>>Mike
>>>
>>>
>>
>>As far as I knew, you can't do that. Computer names have to be unique
>>withing the same network. Depending on the DHCP server you are using
>>(OS wise) it should record the MAC address of the requesting machine.
>>Check the logs to see if it is indeed the License server that is making
>>the request.
>>
>>It's possible that the Flexlm server software installed some network
>>stuff that is requesting a DHCP address. I would check the settings on
>>the server to see if that's the case. But this is purely speculation,
>>since I am unfamiliar with the Flexlm software.
>>
>>Cheers,
>>CMF
>>
>
>
>
Message 7 of 10
Anonymous
in reply to: Anonymous

So, if you ping the rouge addresses, the ping fails? If you get an answer
from ping try running arp -A to take a look at the MAC addresses. On the
DHCP servers side make sure that the rouge IPs are not reserved or held
under lease.

--
Jerry Milana,
Autodesk Professional Services

"rich" wrote in message
news:3FEFFEC05A54274EA02AD05D043E7145@in.WebX.maYIadrTaRb...
> None of that seems to apply. There is only one adapter defined in "My
> Network Places". Ipconfig lists what it is supposed to list (one adapter
> at the static address). Nothing exists at the rouge addresses.
> Yesterday we tried disabling the dhcp client service on the license
> server to no avail.
>
> The only strange thing that I've found is an "Incomming Connections"
> item in "MY Network Places" but it seems to be part of another licnece
> managment software that uses a parallel port key. I disabled all tcp/ip
> functions related to it.
>
> sigh, it's the problem that won't go away. 4 sets of eyes have examined
> it so far.
>
> jerry milana wrote:
>
> > The only way I can think of that DHCP will hand out three IP addresses
is if
> > there were network interfaces to assign them to. At a Command prompt
(DOS)
> > type IPCONFIG /ALL and see how many adapters are defined on that server.
> > Also look at the descriptions of the adapters, some may be logical
adapters
> > and the description should provide you a clue as to their source. What
> > happens if you ping these phantom IP addresses?
> >
> > I do not know of anything in the FLEXlm license management system that
could
> > trigger this behavior.
> >
> > --
> > Jerry Milana,
> > Autodesk Professional Services
> >
> > "Chris Ferris" wrote in message
> > news:74B6AF923BE487ADAE72799B9E86DCA4@in.WebX.maYIadrTaRb...
> >
> >>
> >>
> >>>I doubt your server is the one requesting the IP. Could it be another
> >>>machine with the same name?
> >>>
> >>>Mike
> >>>
> >>>
> >>
> >>As far as I knew, you can't do that. Computer names have to be unique
> >>withing the same network. Depending on the DHCP server you are using
> >>(OS wise) it should record the MAC address of the requesting machine.
> >>Check the logs to see if it is indeed the License server that is making
> >>the request.
> >>
> >>It's possible that the Flexlm server software installed some network
> >>stuff that is requesting a DHCP address. I would check the settings on
> >>the server to see if that's the case. But this is purely speculation,
> >>since I am unfamiliar with the Flexlm software.
> >>
> >>Cheers,
> >>CMF
> >>
> >
> >
> >
>
Message 8 of 10
Anonymous
in reply to: Anonymous

The ping fails. Basicly it looks like cadstuff (the license server)
asks for an address, dhcp assigns it, but cadstuff doesn't do anything
with it except ask again a few hours later. Oh, and it doesn't just ask
once, noooo, it asks twice and of course gets two addresses allocated!

The problem may be fixed now but unfortunatly it appears to be a mystery
fix. We turned off the dhcp client on cadstuff with no effect but upon
reboot it doesn't appear to broadcasting anymore requests. We'll know
for sure on friday morning if it really worked.

jerry milana wrote:
> So, if you ping the rouge addresses, the ping fails? If you get an answer
> from ping try running arp -A to take a look at the MAC addresses. On the
> DHCP servers side make sure that the rouge IPs are not reserved or held
> under lease.
>
> --
> Jerry Milana,
> Autodesk Professional Services
>
> "rich" wrote in message
> news:3FEFFEC05A54274EA02AD05D043E7145@in.WebX.maYIadrTaRb...
>
>>None of that seems to apply. There is only one adapter defined in "My
>>Network Places". Ipconfig lists what it is supposed to list (one adapter
>>at the static address). Nothing exists at the rouge addresses.
>>Yesterday we tried disabling the dhcp client service on the license
>>server to no avail.
>>
>>The only strange thing that I've found is an "Incomming Connections"
>>item in "MY Network Places" but it seems to be part of another licnece
>>managment software that uses a parallel port key. I disabled all tcp/ip
>>functions related to it.
>>
>>sigh, it's the problem that won't go away. 4 sets of eyes have examined
>>it so far.
>>
>>jerry milana wrote:
>>
>>
>>>The only way I can think of that DHCP will hand out three IP addresses
>
> is if
>
>>>there were network interfaces to assign them to. At a Command prompt
>
> (DOS)
>
>>>type IPCONFIG /ALL and see how many adapters are defined on that server.
>>>Also look at the descriptions of the adapters, some may be logical
>
> adapters
>
>>>and the description should provide you a clue as to their source. What
>>>happens if you ping these phantom IP addresses?
>>>
>>>I do not know of anything in the FLEXlm license management system that
>
> could
>
>>>trigger this behavior.
>>>
>>>--
>>>Jerry Milana,
>>>Autodesk Professional Services
>>>
>>>"Chris Ferris" wrote in message
>>>news:74B6AF923BE487ADAE72799B9E86DCA4@in.WebX.maYIadrTaRb...
>>>
>>>
>>>>
>>>>
>>>>>I doubt your server is the one requesting the IP. Could it be another
>>>>>machine with the same name?
>>>>>
>>>>>Mike
>>>>>
>>>>>
>>>>
>>>>As far as I knew, you can't do that. Computer names have to be unique
>>>>withing the same network. Depending on the DHCP server you are using
>>>>(OS wise) it should record the MAC address of the requesting machine.
>>>>Check the logs to see if it is indeed the License server that is making
>>>>the request.
>>>>
>>>>It's possible that the Flexlm server software installed some network
>>>>stuff that is requesting a DHCP address. I would check the settings on
>>>>the server to see if that's the case. But this is purely speculation,
>>>>since I am unfamiliar with the Flexlm software.
>>>>
>>>>Cheers,
>>>>CMF
>>>>
>>>
>>>
>>>
>
>
Message 9 of 10
Anonymous
in reply to: Anonymous

"rich" wrote in message
news:C815BBC2759CBA8656F54A4EEEEF7D52@in.WebX.maYIadrTaRb...


Ok. let's get a little more granular, starting with DHCP.

In the DHCP manager, are you seeing seperate addresses under address leases?
To machines with the same cadstuff name? Are the Unique IDs the same?

Mike
Message 10 of 10
Anonymous
in reply to: Anonymous

Mike Donahue wrote:
> "rich" wrote in message
> news:C815BBC2759CBA8656F54A4EEEEF7D52@in.WebX.maYIadrTaRb...
>
>
> Ok. let's get a little more granular, starting with DHCP.
>
> In the DHCP manager, are you seeing seperate addresses under address leases?
> To machines with the same cadstuff name? Are the Unique IDs the same?
>
> Mike
>
>
For starters, some people know better than to use windows servers 😉 My
dhcp/dns server us running on linux. But to answer your questions.
Each of the addresses are handed out to cadstuff and the mac matches
what is on cadstuff. The only anomily with the names is that one
address is given to the host name and the other goes out to it's fdqn.

Not to spoil anyones fun but we managed to make the problem go away but
we still don't understand why it happened. I'm more than happy to keep
working this out if it might help me to understand why it happened.

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