When running an Ubuntu server on RHEL6 the dhclient on Ubuntu will report 'bad udp checksum' in response to the DHCP Offer packets coming from the Host.
This is on a libvirt controlled KVM system using libvirt controlled dnsmasq processes on the Host.
Optimisations within the kernel appear to be upsetting dhclient.
http://www.pubbs.net/201004/dhcp/30492-dhcpd-problem-on-virtual-machines.html
ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: linux-image-2.6.32-24-generic-pae (not installed)
Regression: Yes
Reproducible: Yes
ProcVersionSignature: User Name 2.6.32-24.38-generic-pae 2.6.32.15+drm33.5
Uname: Linux 2.6.32-24-generic-pae i686
AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access /dev/snd/: No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory
Architecture: i386
ArecordDevices: Error: [Errno 2] No such file or directory
CurrentDmesg:
[ 13.240032] eth0: no IPv6 routers present
[ 2868.734972] psmouse.c: Explorer Mouse at isa0060/serio1/input0 lost synchronization, throwing 1 bytes away.
Date: Tue Jul 27 09:33:31 2010
Lspci: Error: [Errno 2] No such file or directory
Lsusb: Error: [Errno 2] No such file or directory
MachineType: Red Hat KVM
PciMultimedia:
ProcCmdLine: root=UUID=129537b3-af8e-4e06-bd9d-06626fa40823 ro quiet splash
ProcEnviron:
LANG=en_GB.UTF-8
SHELL=/bin/bash
SourcePackage: linux
dmi.bios.date: 01/01/2007
dmi.bios.vendor: Seabios
dmi.bios.version: 0.5.1
dmi.chassis.type: 1
dmi.chassis.vendor: Red Hat
dmi.modalias: dmi:bvnSeabios:bvr0.5.1:bd01/01/2007:svnRedHat:pnKVM:pvrRHEL6.0.0PC:cvnRedHat:ct1:cvr:
dmi.product.name: KVM
dmi.product.version: RHEL 6.0.0 PC
dmi.sys.vendor: Red Hat
Description of problem:
While running an Ubuntu Lucid virtual server under kvm on RHEL6, the DHCP system reports 'bad udp checksum' in response to DHCP offer packets coming from the libvirt launched dnsmasq process on the Host. Comparing RHEL5 to RHEL6 show that tx checksumming is switched on across the 'vnet' interfaces.
Version-Release number of selected component (if applicable):
kernel.x86_64 2.6.32-44.1.el6 @anaconda-
How reproducible:
Setup a virtual network handing out DHCP addresses and run a virtual machine running dhclient3. If you run the dhclient3 in the console, you will see 'bad udp checksum in 5 packets' errors. tcpdump shows that the DHCP offer packet are reaching the virtual machine.
Steps to Reproduce:
1.
2.
3.
Actual results:
'bad udp checksum in 5 packets'
Expected results:
virtual machine picks up the ip address as normal.
Additional info:
http://