[Bug 974454] [NEW] resolv.conf loses search directive with domain during pxe boot

Mac Welch learn2mac at gmail.com
Thu Apr 5 17:25:05 UTC 2012 

Public bug reported:

When performing a pxe boot using the netboot image from the precise-
server-amd64 iso, resolv.conf is modified and the search directive
containing the domain provided by dhcp is removed. I can see that the
entry is picked up during the boot of the image initially. The file is
then overwritten removing the search directive. This seems to correspond
with a reverse dns lookup being used to obtain a hostname as shown in
the log section provided. Running dhclient after this restores the entry
in resolv.conf.

In monitorng resolv.conf, I found that /etc/resolv.conf is populated
with the following information initially during the pxe boot, which is
the result that is needed:

search provision.example.com
nameserver 10.1.0.2

---------------------------

It is then modified to the following:

nameserver 10.1.0.2

------------------------
Apr  5 14:03:33 netcfg[2088]: DEBUG: No RA received; attempting IPv4 autoconfig
Apr  5 14:03:33 netcfg[2088]: WARNING **: Started DHCP client; PID is 2147
Apr  5 14:03:34 dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 1
Apr  5 14:03:34 dhclient: DHCPREQUEST of 10.1.0.112 on eth0 to 255.255.255.255 port 67
Apr  5 14:03:34 dhclient: DHCPOFFER of 10.1.0.112 from 10.1.0.2
Apr  5 14:03:34 dhclient: DHCPACK of 10.1.0.112 from 10.1.0.2
Apr  5 14:03:34 dhclient: bound to 10.1.0.112 -- renewal in 7192 seconds.
Apr  5 14:03:36 kernel: [   21.621493] eth0: no IPv6 routers present
Apr  5 14:03:36 netcfg[2088]: DEBUG: Reading domain name returned via DHCP
Apr  5 14:03:36 netcfg[2088]: DEBUG: DHCP domain name is '**************'
Apr  5 14:03:36 netcfg[2088]: DEBUG: Reading NTP servers from DHCP info
Apr  5 14:03:36 netcfg[2088]: DEBUG: Read NTP server 10.1.0.2
Apr  5 14:03:36 netcfg[2088]: DEBUG: Reading nameservers from /etc/resolv.conf
Apr  5 14:03:36 netcfg[2088]: DEBUG: Read nameserver 10.1.0.2
Apr  5 14:03:36 netcfg[2088]: DEBUG: State is now 1
Apr  5 14:03:36 netcfg[2088]: DEBUG: State is now 2
Apr  5 14:03:36 netcfg[2088]: DEBUG: State is now 5
Apr  5 14:03:36 netcfg[2088]: DEBUG: Using DNS to try and obtain default hostname
Apr  5 14:03:36 netcfg[2088]: DEBUG: Getting default hostname from rDNS lookup of autoconfigured address 10.1.0.112
Apr  5 14:03:36 netcfg[2088]: DEBUG: getnameinfo() returned -3: errno 0 (Success)
Apr  5 14:03:36 netcfg[2088]: DEBUG: Getting default hostname from rDNS lookup of autoconfigured address fe80::250:56ff:feb8:5e
Apr  5 14:03:36 netcfg[2088]: DEBUG: getnameinfo() returned -2: errno 0 (Success)

-------------------

pxelinux.cfg entry:

LABEL default
  MENU DEFAULT
  MENU LABEL Ubuntu 12.04 (64-bit) Installer
  IPAPPEND 2
  KERNEL ubuntu/12.04/amd64/linux
  APPEND interface=auto lang=en_US locale=en_US console-setup/layoutcode=us priority=critical debian-installer/allow_unauthenticated=true initrd=ubuntu/12.04/amd64/initrd.gz url=http://kickstart/cgi-bin/example.cgi ramdisk_size=10882 root=/dev/ram0 devfs=mount,dall rw --

** Affects: netcfg (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: precise

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https://bugs.launchpad.net/bugs/974454

Title:
  resolv.conf loses search directive with domain during pxe boot

Status in “netcfg” package in Ubuntu:
  New

Bug description:
  When performing a pxe boot using the netboot image from the precise-
  server-amd64 iso, resolv.conf is modified and the search directive
  containing the domain provided by dhcp is removed. I can see that the
  entry is picked up during the boot of the image initially. The file is
  then overwritten removing the search directive. This seems to
  correspond with a reverse dns lookup being used to obtain a hostname
  as shown in the log section provided. Running dhclient after this
  restores the entry in resolv.conf.

  In monitorng resolv.conf, I found that /etc/resolv.conf is populated
  with the following information initially during the pxe boot, which is
  the result that is needed:

  search provision.example.com
  nameserver 10.1.0.2

  ---------------------------

  It is then modified to the following:

  nameserver 10.1.0.2

  ------------------------
  Apr  5 14:03:33 netcfg[2088]: DEBUG: No RA received; attempting IPv4 autoconfig
  Apr  5 14:03:33 netcfg[2088]: WARNING **: Started DHCP client; PID is 2147
  Apr  5 14:03:34 dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 1
  Apr  5 14:03:34 dhclient: DHCPREQUEST of 10.1.0.112 on eth0 to 255.255.255.255 port 67
  Apr  5 14:03:34 dhclient: DHCPOFFER of 10.1.0.112 from 10.1.0.2
  Apr  5 14:03:34 dhclient: DHCPACK of 10.1.0.112 from 10.1.0.2
  Apr  5 14:03:34 dhclient: bound to 10.1.0.112 -- renewal in 7192 seconds.
  Apr  5 14:03:36 kernel: [   21.621493] eth0: no IPv6 routers present
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Reading domain name returned via DHCP
  Apr  5 14:03:36 netcfg[2088]: DEBUG: DHCP domain name is '**************'
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Reading NTP servers from DHCP info
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Read NTP server 10.1.0.2
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Reading nameservers from /etc/resolv.conf
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Read nameserver 10.1.0.2
  Apr  5 14:03:36 netcfg[2088]: DEBUG: State is now 1
  Apr  5 14:03:36 netcfg[2088]: DEBUG: State is now 2
  Apr  5 14:03:36 netcfg[2088]: DEBUG: State is now 5
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Using DNS to try and obtain default hostname
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Getting default hostname from rDNS lookup of autoconfigured address 10.1.0.112
  Apr  5 14:03:36 netcfg[2088]: DEBUG: getnameinfo() returned -3: errno 0 (Success)
  Apr  5 14:03:36 netcfg[2088]: DEBUG: Getting default hostname from rDNS lookup of autoconfigured address fe80::250:56ff:feb8:5e
  Apr  5 14:03:36 netcfg[2088]: DEBUG: getnameinfo() returned -2: errno 0 (Success)

  -------------------

  pxelinux.cfg entry:

  LABEL default
    MENU DEFAULT
    MENU LABEL Ubuntu 12.04 (64-bit) Installer
    IPAPPEND 2
    KERNEL ubuntu/12.04/amd64/linux
    APPEND interface=auto lang=en_US locale=en_US console-setup/layoutcode=us priority=critical debian-installer/allow_unauthenticated=true initrd=ubuntu/12.04/amd64/initrd.gz url=http://kickstart/cgi-bin/example.cgi ramdisk_size=10882 root=/dev/ram0 devfs=mount,dall rw --

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