Forcing dhclient to use 255.255.255.255

Hi,

In a fresh FC14 install my log is flooded with dhcp requests:

dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
[..]

After some random time it sends the request to 255.255.255.255 and gets
a reply instantly:

dhclient: DHCPREQUEST on eth1 to 255.255.255.255 port 67
dhclient: DHCPACK from x.y.z.129
dhclient: bound to n.n.n.n -- renewal in 30394 seconds.

Seems it sends the requests to the wrong server - it keeps trying
x.y.z.41, gives up, tryes 255.255.255.255, and gets a reply from x.y.z.129.

Is there a way to force dhclient to use 255.255.255.255 every time?

/Thomas

Il Sun, 20 Feb 2011 19:49:16 +0100, Thomas Rasmussen ha scritto:
[cut]
> Is there a way to force dhclient to use 255.255.255.255 every time?
>
> /Thomas

You need to use

dhclient -r eth1

when you power off. Alternatively you can erase the lease file (usually
under /var/lib/dhclient/).

If dhclient can't find a valid lease for DHCPREQUEST, it sends
DHCPDISCOVER.

Enrico

At 21-02-2011 09:14, Enrico wrote:
> You need to use
>
> dhclient -r eth1
>
> when you power off. Alternatively you can erase the lease file (usually
> under /var/lib/dhclient/).
>
> If dhclient can't find a valid lease for DHCPREQUEST, it sends
> DHCPDISCOVER.

I should have mentioned this is a server, it is never powered off.

eth1 is the internet connection, eth0 is my local network.

It happens every time the lease expires - DHCPREQUEST every 3 or 4
seconds for several hours, until it figures out to use 255.255.255.255

It works, I never loose the internet connection, but it makes it hell to
look through /var/log/messages for "real" problems.

/Thomas

On 21.2.11 10:35 , Thomas Rasmussen wrote:
> At 21-02-2011 09:14, Enrico wrote:
>> You need to use
>>
>> dhclient -r eth1
>>
>> when you power off. Alternatively you can erase the lease file (usually
>> under /var/lib/dhclient/).
>>
>> If dhclient can't find a valid lease for DHCPREQUEST, it sends
>> DHCPDISCOVER.
>
> I should have mentioned this is a server, it is never powered off.
>
> eth1 is the internet connection, eth0 is my local network.
>
> It happens every time the lease expires - DHCPREQUEST every 3 or 4
> seconds for several hours, until it figures out to use 255.255.255.255
>
> It works, I never loose the internet connection, but it makes it hell to
> look through /var/log/messages for "real" problems.
>
> /Thomas

In my Debian, the lease file is in /var/lib/dhcp3/dhclient.eth0.leases.
Please check what is in the last lease as option dhcp-server-identifier.

--

Tauno Voipio
tauno voipio (at) iki fi

In message <4d62cc9a$0$23763$(E-Mail Removed)>, Thomas Rasmussen
wrote:

> ... but it makes it hell to look through /var/log/messages for "real"
> problems.

grep -v is your friend.

On 02/20/2011 07:49 PM, Thomas Rasmussen wrote:
> Hi,
>
> In a fresh FC14 install my log is flooded with dhcp requests:
>
> dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
> dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
> dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
> dhclient: DHCPREQUEST on eth1 to x.y.z.41 port 67
> [..]
>
> After some random time it sends the request to 255.255.255.255 and gets
> a reply instantly:
>
> dhclient: DHCPREQUEST on eth1 to 255.255.255.255 port 67
> dhclient: DHCPACK from x.y.z.129
> dhclient: bound to n.n.n.n -- renewal in 30394 seconds.
>
> Seems it sends the requests to the wrong server - it keeps trying
> x.y.z.41, gives up, tryes 255.255.255.255, and gets a reply from x.y.z.129.
>
> Is there a way to force dhclient to use 255.255.255.255 every time?
>
> /Thomas
>
>

After looking you up at robtex I'm guessing it could be a misconfigured
dhcp server at Bredbånd Nord I/S. Can you contact them?
x.y.z.41 is probably your dns server, x.y.z.129 is the dhcp server.
http://zhigang.org/wiki/DHCP may give you a solution/workaround for your
problem: add "reject x.y.z.41" to your dhclient.conf.

Michel

> After looking you up at robtex I'm guessing it could be a misconfigured
> dhcp server at Bredbånd Nord I/S. Can you contact them?

That is my ISP, I'll try sending them an email to make them aware of the
problem.

> x.y.z.41 is probably your dns server, x.y.z.129 is the dhcp server.
> http://zhigang.org/wiki/DHCP may give you a solution/workaround for your
> problem: add "reject x.y.z.41" to your dhclient.conf.

That should work - I'll do that if my ISP doesn't fix their DHCP server.

Thanks!

/Thomas

At 21-02-2011 22:21, Tauno Voipio wrote:
> In my Debian, the lease file is in /var/lib/dhcp3/dhclient.eth0.leases.
> Please check what is in the last lease as option dhcp-server-identifier.
>

interface "eth1";
fixed-address n.n.n.n;
option subnet-mask 255.255.255.128;

option routers x.y.z.129; <--- This is where I get my IP from

option dhcp-lease-time 86400;
option dhcp-message-type 5;
option domain-name-servers n.n.n.n,n.n.n.n;

option dhcp-server-identifier x.y.z.41; <--- Obviously wrong!

option interface-mtu 576;
option broadcast-address 255.255.255.255;
renew 4 2011/02/24 13:24:03;
rebind 5 2011/02/25 00:20:19;
expire 5 2011/02/25 03:20:19;

I have mailed my ISP with this info - Thanks!

/Thomas