Comments on: Linux Force DHCP client (dhclient) to renew ip address

By: Philip

Philip — Sun, 30 Oct 2011 18:15:55 +0000

You need to tell the dhcp server to issue a different one, typically I dhcp server will if it can issue the same address.

You may be able to tell it to forget what it last issued, or you can usually make a mapping between the mac address of your nic and the ip you want, but generally unless you do something on the server it wil reissue the same address.

By: Danilo

Danilo — Wed, 07 Sep 2011 22:21:03 +0000

Just what i needed!

By: kOz

kOz — Tue, 05 Apr 2011 12:42:49 +0000

Fantastic! Worked like a charm on Ubuntu 10.10! Thanx!

By: David Balažic

David Balažic — Sat, 19 Mar 2011 19:16:00 +0000

Oh, webmaster please fix the typos in my previous post… :-)
(for network device names, use the same one of course, above I used ince eth0, then eth1)

By: David Balažic

David Balažic — Sat, 19 Mar 2011 19:14:04 +0000

More detail, about this not working on Ubuntu:
sudo dhclient -r -pf /var/run/dhclient-eth1.pid -lf /var/lib/dhcp3/dhclient-eth1.lease eth1

This kill the running dhcp daemon which is noticed by Network Manager which then immediately downs the interface, so the dhclient can not send the DHCPRELEASE packet.

The solution is to disable NM (right clik on its icon and uncheck the first option “Enable Netwroking” – this is so on Ubuntu 10.10, other version might look a bit different), kill existing dhclient processes, then establish the connection manually, run dhclient eth0 , then run the above dhclient command to release the IP.

For connection to WPA protected WLAN networks follow the description on http://linux.icydog.net/wpa.php

(In windows this is justa matter of running “ipconfig /release wirelless*” :P )

By: Mike Bethany

Mike Bethany — Sat, 19 Feb 2011 16:45:32 +0000

If you’re having problems getting your Linux distro to get a new IP the easiest thing to do is to just reboot your router (assuming you can do that). If that doesn’t work you can add the old address as a statically assigned DHCP address to a bogus MAC address. This will lock the Linux box out of it’s old address and force it to get the new address.

By: jamkomo

jamkomo — Fri, 04 Feb 2011 03:06:23 +0000

Well, it releases them, but when I renew it, it gives me the same ip back. I wanted a new IP. Is there way to force a NEW one?

By: Christian

Christian — Wed, 19 Jan 2011 18:45:10 +0000

Thank for your solution, really help me.

By: jeffory

jeffory — Wed, 17 Nov 2010 04:17:31 +0000

@ David Balažic

It wasn’t working for me for me with Ubuntu 10.04…[continued if this posts]

By: PCG

PCG — Thu, 27 May 2010 09:22:04 +0000

briliant!

By: Flyte

Flyte — Thu, 18 Feb 2010 02:27:38 +0000

I set up static DHCP assignments and then needed to switch my server over to DHCP. To do this remotely I simply put the two commands on a single line:

dhclient -r; dhclient

If you’ve set up the static DHCP to use the IP address that you’ve already given it then you shouldn’t become disconnected from your SSH session :)

By: Eduardo Calvillo

Eduardo Calvillo — Mon, 01 Feb 2010 19:35:55 +0000

Thank you for the recommendation, it works good.

By: How to Assign IP Address In DHCP in Linux

How to Assign IP Address In DHCP in Linux — Mon, 23 Nov 2009 05:56:41 +0000

Dear sir
Please Help Me
How t o Assign IP Address For DHCP Client Linux..

Thanks

By: David Balažic

David Balažic — Wed, 07 Oct 2009 22:35:27 +0000

Nope. After sudo dhclient -r the interface still has the IP address. See details: http://pastebin.com/f8d2a4e2

By: Schmid Hans-Peter

Schmid Hans-Peter — Wed, 07 Oct 2009 15:19:56 +0000

Works for me on Ubuntu 9.04. It seems to me, that the network-manager does not notice the change. After sudo dhclient -r the command ifconfig eth0 shows no ip address at the interface. After sudo dhclient the command ifconfig eth0 shows an ip address again.

Thank you

By: David Balažic

David Balažic — Tue, 01 Sep 2009 17:52:45 +0000

This does not work on Ubuntu 9.04

It seems that network manager runs it own copy of dhclient.

By: Thamizhannal

Thamizhannal — Fri, 07 Aug 2009 07:24:55 +0000

This command worked me..thanks a lot

By: anon

anon — Wed, 08 Jul 2009 01:21:33 +0000

Thanks!

By: thehuyvb

thehuyvb — Mon, 22 Jun 2009 02:13:07 +0000

Thanks so much! it’s work ^^

By: synick

synick — Thu, 27 Nov 2008 07:10:34 +0000

Hi,

This worked great, I was having a bit of problems thought worked them out in the end, thought I would share.

I unplugged the network cable, then plugged back in a couple minutes later. Couldn’t access network, tried dhclient -r command and didn’t work. Found that dhcpcd was still running, so done a killall -9 dhcpcd then executed dhclient…worked!