Dear Maintainer,
there are some points of reported problem:

- DHCP server is used like secondary server for failover high avalability service
- problem with 100% CPU consuming
- service was troubleshooted with commands: strace dhcpd -f

Problem output:

read(8, "", 4047)                       = 0
gettimeofday({1363957696, 815455}, NULL) = 0
select(22, [4 5 7 8 9], [], NULL, {13, 422598}) = 1 (in [8], left {13, 422596})
gettimeofday({1363957696, 815495}, NULL) = 0
gettimeofday({1363957696, 815511}, NULL) = 0

Having just witnessed the same symptoms on our production service I
performed a quick investigation.

This revealed that dhcpd was iterating over a gettimeofday ... select
loop in which select was returning immediately with three sockets to
the failover peer that were in CLOSE_WAIT state. I was unable to debug
further since restoring service was a priority.

I shall add this to my ever growing list of failure modes for the ISC
DHCP server failover implementation.

I believe this is a bug in the ISC dhcpd.  However, I did solve it in my
case (Debian Wheezy isc-dhcp-server 4.2.2.dfsg.1-5+deb70u6).

netstat -pant|grep dhcp
revealed a lot of CLOSE_WAIT sockets to my DHCP server's failover
partner (Ubuntu Trusty isc-dhcp-server 4.2.4-7ubuntu12).

It turned out that the secondary Ubuntu machine had two copies of dhcpd
running (ps aux|grep dhcpd).  Killing the rogue version, and restarting
the primary Debian version cleared up the issue.

But the dhcpd still treats CLOSE_WAIT sockets incorrectly....

Daniel

Hi dear,

It's a pleasure meeting you! My name is Shaye, from USA, a US Amry, base in
Libya Military Camp, I have an important issue to discuss with you, please
reply me for more discussion.

Regards
Lt. Shaye

Dear submitter,

as the package isc-dhcp has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1143544

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)