[Bug 930962] Re: dhcp3-server reports many bad udp checksums to syslog using virtio NIC

Thu Jan 17 23:54:21 UTC 2013

This bug was fixed in the package isc-dhcp - 4.2.4-4ubuntu1

---------------
isc-dhcp (4.2.4-4ubuntu1) raring; urgency=low

  * Merge from Debian, remaining changes:
    - Apparmor profiles for dhclient and dhcpd.
    - Upstart jobs for isc-dhcp-server, isc-dhcp-server6, isc-dhcp-relay and
      isc-dhcp-relay6. (LP: #944849)
    - Separate default file for isc-dhcp-relay6. (LP: #944849)
    - Apport hook for isc-dhcp-client and isc-dhcp-server.
    - dhclient.conf: Set for IPv6 (dhcp6.*) (LP: #770324)
    - If /etc/ltsp/dhcpd.conf exists, use that instead of /etc/dhcp/dhcpd.conf
    - Drop isc-dhcp-server/new_auth_behavior question from high to medium
    - Create user/group dhcpd (LP: #727837)
    - Create /etc/dhcp/ddns-keys/ for DDNS updates (LP: #341817)
    - Build with extra hardening and use --enable-paranoia to run dhcpd as user
      (LP: #727837)
    - Add IPv6 support to dhclient-script.linux.udeb
    - Wait for /etc/resolv.conf to be writable in dhclient-script.linux.
      (LP: #856984)
    - Sanitize environment in dhclient-script.linux. (LP: #1045986)
    - Don't call 'ip addr flush' as it breaks IPv6 networking. (LP: #1023174)
    - debian/apparmor-profile.dhclient: update to add the new paths used by
      NetworkManager for its conf and leases files; standardized under
      /var/lib/NetworkManager.
    - Remaining Ubuntu patches:
      + dhclient-fix-backoff
      + dhclient-more-debug (LP: #35265)
      + dhclient-safer-timeout (LP: #838968)
      + dhcpd.conf-subnet-examples (LP: #26661)
      + multi-ip-addr-per-if (LP: #717166)
      + onetry_retry_after_initial_success (LP: #974284)
      + revert-next-server
    - Dropped Ubuntu patches:
      + dhclient-onetry-call-clientscript (now in Debian)
  * Fix isc-dhcp-server-ldap not actually containing ldap support.
    Thanks to Christian Hoffmann for tracking down the issue. (LP: #1071928)
  * Don't set fqdn.fqdn in dhclient.conf as that seems to confuse some DHCP
    servers. An alternative would have been to only set fqdn.fqdn and not
    host-name, but that appears to confuse another set of servers.
    For now go with just host-name which is the most common and if becomes a
    big problem for IPv6 (where fqdn.fqdn is apparently required), then we'll
    need to have a separate dhclient6.conf file and change all the calls to
    dhclient -6 to use that file instead. (LP: #1088682)
  * Include patch from RedHat/Fedora to deal with hardware/xen/virtio offload
    of UDP checksums. (LP: #930962)

isc-dhcp (4.2.4-4) unstable; urgency=medium

  * Run exit hooks when "dhclient -1" fails (closes: #486520).
  * Add dhcp6.name-servers and dhcp6.domain-search to the default request
    options in dhclient.conf (closes: #693315).
 -- Stephane Graber <stgraber at ubuntu.com>   Thu, 17 Jan 2013 17:09:14 -0500

** Changed in: isc-dhcp (Ubuntu)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/930962

Title:
  dhcp3-server reports many bad udp checksums to syslog using virtio NIC

Status in “isc-dhcp” package in Ubuntu:
  Fix Released

Bug description:
  Tested with  dhcp3-server ver. 3.1.3-2ubuntu3.3  in Ubuntu 10.04.3
  Server, x64.

  The DHCP server reports that UDP packets sent to it have bad
  checksums:

  Feb 11 06:57:18 ... dhcpd: 5 bad udp checksums in 5 packets
  Feb 11 06:58:22 ... dhcpd: last message repeated 7 times
  Feb 11 06:59:17 ... dhcpd: last message repeated 7 times

  The DHCP server host is a KVM virtual machine using a virtio-based
  virtual NIC.

  This problem has been reported for other distros using KVM and virtio:

  https://bugs.mageia.org/show_bug.cgi?id=1243

  http://www.mail-archive.com/kvm@vger.kernel.org/msg41958.html
   - suggests using iptables to write in a checksum

  http://pkgs.fedoraproject.org/gitweb/?p=dhcp.git;a=blob;f=dhcp-4.2.2-xen-checksum.patch;h=038d346d726e131f1ab2579fe015a72b49733a0d;hb=HEAD
   - Fedora patch to dhcp to avoid this

  The simplest workaround is to change the virtual NIC type from virtio
  to Intel e1000 in KVM. Apparently this driver calculates checksums.
  But virtio is the default driver type.

  Thanks,
  Tim Miller Dyck

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