IP Address Randomly Changes???

dvc5 · Posted: Mon Mar 22, 2004 7:27 am Post subject: IP Address Randomly Changes???

I searched around a bit and couldn't really find anything like this. I've got a server that's sitting on a small subnet of a home router that's configured to give out IP Addresses through DHCP. Tonight I tried to login to the server to do the usual log-checking and backups and low-and-behold, I couldn't login to 192.168.0.13...I did a check on the router for "attached devices" and there was a machine connected on 192.168.0.15. Sure enough, this was the server.
So somehow the IP address changed for this box even though I hadn't logged into it and changed it manually. Everything seemed fine (ran chkrootkit, rc-status, etc) and there was no unusual log activity. Is this something that can happen with DHCP? Any information on this interesting phenomenon would be greatly appreciated. :roll:

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Crimson Rider · Posted: Mon Mar 22, 2004 8:43 am Post subject:

Yes it's something that could happen with DHCP.

If it's getting the address from DHCP it's entirly possible that the DHCP server for some reason or another gives it another adress.

Some sys admins even force this behaviour as a sort of security. Random changing the IP over the network to deny hackers access.

This post was answered in accordance with "the adopt an unanswered post initiative today"
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Code, justify, code - Pitr Dubovich

dvc5 · Posted: Mon Mar 22, 2004 8:49 am Post subject:

Thanks for the quick reply. That's certainly the type of answer I was hoping to hear. I thought it might be possible, just kinda weird that it's never done that before.

_________________
#define NULL rand() /*heh heh heh */

Green Is Good

Crimson Rider · Posted: Mon Mar 22, 2004 9:23 am Post subject:

Maybe you changed something about your computer, or perhaps it's a date/time thing. Anyway, seems like the lease expired and it just issued a new ip lease instead of prolonging the old one.

good luck.
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Code, justify, code - Pitr Dubovich

dvc5 · Posted: Thu Mar 25, 2004 4:03 am Post subject:

Just an update, I've set the server to statically assign an IP address to eth0. No more of this dhcp madness! :twisted:

_________________
#define NULL rand() /*heh heh heh */

Green Is Good

Crimson Rider · Posted: Thu Mar 25, 2004 9:32 am Post subject:

Actually DHCP is quite usefull.

It is used for a lot of things. For instance, Demon NL, my ISP, used DHCP to provide me with my static IP. I also use DHCP to allow anyone with a reasonably modern computer to plug in at my home/office and be online instantly. This works both for Windows boxes and Linux computers.

It takes some getting used to, but DHCP is superb in corporate networks. I mean would you like to change the IP's of a few hundred machines by hand ? (Or run the risk that you have indentical IP and other such conflicts ? )
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Code, justify, code - Pitr Dubovich

dvc5 · Posted: Thu Mar 25, 2004 9:36 am Post subject: