DHCP problem

Posted on 2002-04-16
Medium Priority
Last Modified: 2012-06-21

I have a machine running WindowsXP and Linux.

I get my ip-number by dhcp. If I shutdown XP
the dhcp will not give me a new ip-number in linux until after one hour (the lease time) I have no problems the other way... It seems lik the ip-address don't get released when I shutdown XP.
(if I fake a new hw address for my network-card in linux the network works after restarting from XP.)

Is there any way to solve my problem or whos as should I kick.
(My Internet Provider because their dhcp server sucks or Microsoft because XP don't relese the address when I shut down the machine?

Question by:hulken
  • 3
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  • +7

Expert Comment

ID: 6945277
Only a comment:
Try to disable the network card before you shut down the XP.

Expert Comment

ID: 6946371
well, I don't htink it should matter if XP releases the ip address or not. When Linux boots up, it should try to obtain an IP address. Is the DHCP server a windows server? is it ont eh same LAN?
LVL 41

Expert Comment

ID: 6946543
create a batch file and in it have it say
ipconfig /release all
save it as release.bat on your desktop
then just double click on the release.bat before you shut down
then when you boot up linux it should have no problem
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LVL 41

Expert Comment

ID: 6946546
Is this a dilaup conenction or dsl/cable?

Expert Comment

ID: 6946553
I agree with ymash, it shouldn't matter if it releases it or not.

Im not sure what type of Internet connection you have, but some providers require that your machine has a certain computer name to obtain an IP address. -- just a thought.  Not use if this is the same with Linux however.

Expert Comment

ID: 6946682
Just a quick comment I work for an ISP doing cable modem installs and troubleshooting.  Although were are full DHCP at my company, we don't release ips everytime a person shutsdown a computer.  even if you go to Winipcfg in run and hit release and renew  a whole bunch of times, your still gonna get the same ip, sometimes you could have the same ip for about a day or two.

One thing i wasn't quite sure about from your question was that is the fact that you're not constantly getting a new ip bothering you or are you saying that your not pulling an ip at all when you restart???

Author Comment

ID: 6947101
What bathering me is if I go from linux back to xp and so on for a several times I can not acces the net because the dhcp server is locked on my network card's hardware address and wont give me a new address. (if I don't get a new address I can not acces the network outside my subnet  for some reaseon. Probably because the lock the ip-number to my mac address or something.

In linux I have no problem because I have modifyed my startup script to fake another mac address for my card.

Expert Comment

ID: 6947556
First off, I have never heard of ANY DHCP client to ever perform a release at shutdown.  This just isn't how DHCP works.  Second, you mention you are modifying the MAC for Linux.  Most ISPs will only allow 1 MAC to have an IP at a time unless you are paying for more.  This is probably why you have to wait for the release time to get the new IP.  If you were to leave the MAC the same, your Linux box would probably grab the same IP the XP build is grabbing.  Otherwise, talk to your ISP and see if they will give an IP to a second MAC, which will probably cost you a little bit more.

Author Comment

ID: 6947643
The DHCP server will give me a new ip-address for up to 5 different MAC adresses. And if I leave the MAC at the same as in XP I will not get any ip-address at all from the dhcp server. (or if I get one I can't access the net outside my default gateway.

Expert Comment

ID: 6947668
I'm confused - if you are able to modify 1 of the MAC's and get an IP for both of them, what is the problem?  Also, your original question was about releasing addresses automatically, which isn't normal behaviour for a DHCP client.  If you need assistance in troubleshooting other problems such as non-responding subnets, then please provide additional detail about your network, including how you connect to your ISP, subnets involved, addressing, masking, etc.

Expert Comment

ID: 6948388
are you using software from your ISP to get you DNCP address? by default, you computer will ask the DHCP server for teh same address everytime it boots up, if the address is avialable them you get it, if not, it will assign a different one. Sounds to me that the problem is at the ISP. You should talk to them about it and see what they say!
LVL 24

Expert Comment

ID: 6948895
> whos as should I kick.

generally stick tongue out at all, but kick ISP

DHCP address goes to MAC. Not to OS.
Whether asking for new address or renewal, DHCP server should give the one 'currently' assigned, which lasts for a period (hours) after it was released.

Try your winIPcfg. Renew. Renew. Release. Renew.
Should be consistent on gaining and regaining same IP.

Likely the ISP is using some 'enhancement' that some mfr (like MS) made up to be compatible with RFC while not compliant
LVL 24

Accepted Solution

SunBow earned 400 total points
ID: 6949030
oops. Misread the Q, but same answer from me.

Rephrasing, Out of some 'friendliness', dhcp server can retain memory of old IP after it was released, for a period. As I recall, an MS one would hold for hours, even days, for long leases - but not the entire lease period. At least early Windoze workstations released or forgot IPs upon shutdown. But they'd get same one back the next day.

The server sort of hands out leases to addresses not used, or not in quite a while. This can aid pooling, batching, and garbage collection (not that it is needed), especially when sufficient addresses available.

But for ISP, the presumption is that there are less addresses than subscribers, so that they'd be a wanting to free the address ASAP. Such as, taking it away from PC once it is detected as unresponsive. If lease is as much as an hour or more, - I guess they don't need 'em so much after all.

How about ... trying second NIC? Now that they are getting down to $10 ea, it could be contingency to have 2nd one plugged in for case of one going bad. Use one for each OS until then. Hmm?
LVL 24

Expert Comment

ID: 6949049
> by default, you computer will ask the DHCP server for teh same address everytime it boots up

No, Not so. If addresss released, it asks for new one. But as above, server likely remembers and provides old one.

If not released, then computer asks for renewal of original address for roughly 3/4 - 7/8 of the designated lease period (differs by OS/mfr). Computer will actually start asking for a 'new' address prior to lease period expiring (not wanting to be caught without a legit one, it broadcasts everywhere to get anything, before time runs out).

scraig84> if you are able to modify 1 of the MAC's and get an IP for both of them, what is the problem?


thus if there is some remaining problem, my guess is ISP

Author Comment

ID: 6950124
I guess that the best way to solve my problem is to create
a service that runs ipconfig /release on shutdown.

Expert Comment

ID: 6975994
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