[Dnsmasq-discuss] DHCP Issue

richardvoigt at gmail.com richardvoigt at gmail.com
Sun Jul 22 02:50:56 BST 2007


On 7/22/07, Steven <steven3k at gmail.com> wrote:
>
> Many thanks!!!
>
> I disabled checksum offload with this command:
>
> sudo ethtool -K eth0 rx off tx off
>
> and now everything works... :)



Glad to hear it.

In most cases the checksum offload only messes up wireshark capture but I've
also seen some cases where the actual packets on the wire are corrupt.
Never very nice to be one of the bug cases.


On 7/22/07, Steven <steven3k at gmail.com> wrote:
> > Hi,
> >
> > The card on the server is this:
> >
> > steven at steven-desktop:~$ lspci | grep Marvell
> > 02:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8053
> > PCI-E Gigabit Ethernet Controller (rev 15)
> >
> >
> > On 7/22/07, richardvoigt at gmail.com <richardvoigt at gmail.com> wrote:
> > >
> > >
> > > On 7/21/07, Simon Kelley <simon at thekelleys.org.uk> wrote:
> > > > Steven wrote:
> > > > > Hi,
> > > > > I have a problem setting up a dhcp server using dnsmasq.
> > > > >
> > > > > Seems that the server is working fine but the client are not able
> to
> > > > > get an ip address.
> > > > > The interface on the server is configured to have a static IP
> address,
> > > > > and on the client DHCP is used (obviously).
> > > > > The client sends a DHCPDISCOVER packet, dnsmasq receives it and
> sends
> > > > > a DHCPOFFER packet, but the client doesn't recognizes this packet
> (i
> > > > > think).
> > > > > With other dhcp server (as dhcp3-server) everything is working
> fine,
> > > > > so i suspect this may be an issue with dnsmasq or my config file.
> > > > >
> > > > > I'm using Ubuntu, Feisty Fawn, Linux steven-laptop
> 2.6.20-16-generic
> > > > > #2 SMP Thu Jun 7 20:19:32 UTC 2007 i686 GNU/Linux
> > > > >
> > > >
> > > > The explanation for dhclient ignoring the DHCPOFFERS seems to be
> that
> > > > the UDP checksum is incorrect. Is the Ubuntu system the client, or
> the
> > > > server? The checksum problem seems to be  originating on the server,
> and
> > > > if the server is running Ubuntu (or any Linux distro) then it's a
> kernel
> > > > problem: on Linux dnsmasq delegates UDP and IP header creation to
> the
> > > > kernel. If you are running dnsmasq on *BSD, then it could be a
> dnsmasq
> > >
> > > What kind of network card on the server?  Some fancy ones support
> "checksum
> > > offload" and this has bugs more often than not.
> > >
> > > > problem: on those platforms (some of) the UDP and IP headers are
> created
> > > > by dnsmasq itself.
> > > >
> > > > Cheers,
> > > >
> > > > Simon.
> > > >
> > > > _______________________________________________
> > > > Dnsmasq-discuss mailing list
> > > > Dnsmasq-discuss at lists.thekelleys.org.uk
> > > >
> > > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> > > >
> > >
> > >
> >
>
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