[Bug 1292019] Re: ubuntu causes DHCP DOS attack during install

[Jeremiah Bailey]

This also affects me, I tried with Ubuntu server iso as well as the
netboot tarball.  I have tried using an automated install via preseed as
well as KS and a manual install just loading the kernel and initrd via
tftp.  ALL of these methods result in a loop where the client receives a
DHCPOFFER from the server(which in my case is our network firewall),
this is then followed by a DHCPACK, then the client DHCPDECLINES and
keeps looping through all available DHCP addresses in the pool until the
DHCP server has no more addresses to give out.

There appears to be an old similar bug here:
https://bugs.launchpad.net/ubuntu/+source/netcfg/+bug/848072

Is anyone able to look into this?  I have been beating my head against
the wall for about a week now and could really use some assistance.

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https://bugs.launchpad.net/bugs/1292019

Title:
  ubuntu causes DHCP DOS attack during install

Status in “netcfg” package in Ubuntu:
  Confirmed

Bug description:
  While installing ubuntu server 14.4 or older version 13 we have an DOS
  on DHCP

  During the install at the detect network IP using DHCP we have had
  issues where if this process is left on this screen overnight we have
  about 10 million DHCP request/decline events.  (a request every ~4ms)

  1.  click detect IP using DHCP... the bar goes across the screen then gives up...
  2.  leave the installer at the screen [retry network detection].
  3. /detection seems to still continue in a background process/

  This is extremely aggressive on our network.

  Please have someone look into this before the LTS release.

  Thanks.

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