Arch Linux

Coret

Member

Registered: 2017-01-08

Posts: 8

DHCP server offering IP to itself

I am not entirely sure this is an issue or a mistake of configuration on my part, but I noticed that the DHCP server finds its own MAC on the network and the offers an IP address. Wether I place a fixed IP on the conf file for the server or not I noticed this behavior, this is what the log file shows:

Jan 21 17:46:48 arch dhcpd[18097]: DHCPDISCOVER from fc:aa:14:55:9e:3d via enp2s0
Jan 21 17:46:48 arch dhcpd[18097]: DHCPOFFER on 192.168.25.2 to fc:aa:14:55:9e:3d via enp2s0
Jan 21 17:47:52 arch dhcpd[18097]: DHCPDISCOVER from fc:aa:14:55:9e:3d via enp2s0
Jan 21 17:47:52 arch dhcpd[18097]: DHCPOFFER on 192.168.25.2 to fc:aa:14:55:9e:3d via enp2s0

To me this doesn't seem very problematic, but it generates unnecessary logs. Is there a way to make the dhcp server ignore its own MAC address?

Slithery

Administrator

From: Norfolk, UK

Registered: 2013-12-01

Posts: 5,776

Re: DHCP server offering IP to itself

Don't use DHCP on the server, set it up with a static IP.

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No, it didn't "fix" anything. It just shifted the brokeness one space to the right. - jasonwryan
Closing -- for deletion; Banning -- for muppetry. - jasonwryan

aur - dotfiles

x33a

Forum Fellow

Registered: 2009-08-15

Posts: 4,587

Re: DHCP server offering IP to itself

Coret, you mention that setting a static ip doesn't work. Elaborating on slithery's suggestion, ensure that you have disabled dhcp client service on the server.

Coret

Member

Registered: 2017-01-08

Posts: 8

Re: DHCP server offering IP to itself

I set the server with a fixed IP using netctl configuration, here is the file:

Interface=enp2s0
Connection=ethernet
IP=static
Address=('192.168.25.2/24')
Gateway=('192.168.25.1')
DNS=('192.168.25.1')

## For IPv6 autoconfiguration
#IP6=stateless

## For IPv6 static address configuration
IP6=no

I do believe that is all that I needed to do.

I still think, based on the logs, that the DHCP server "saw" that mac address on the network and offered the IP address. Though to be sure I would need to use TCP dump and analyze the network packages...

Coret

Member

Registered: 2017-01-08

Posts: 8

Re: DHCP server offering IP to itself

Managed to fix it, turns out there a configuration on the dhcpd conf file that can be used to ignore a mac address. With that in place there were no more of those logs messages.