ISC DHCP 4.1-ESV-R14b1 is now available for download

Shawn Routhier sar at
Wed Sep 7 17:46:22 UTC 2016

This is the first beta release of ISC DHCP 4.1-ESV-R14,
a maintenance release which contains a number of bug fixes.

Field testing is an important part of our quality process.
Please report bugs to dhcp-bugs at

A list of the changes in this release has been appended to the end
of this message.  For a complete list of changes from any previous
release, please consult the RELNOTES file within the source distribution.
They can also be found at:

Knowledge base articles about various features can be found starting from:

Webinars can be found here:

This release, and its OpenPGP-signatures are available now from:

ISC's Release Signing Key can be obtained at:

The following are changes that may be more interesting and require
a bit more explanation.

The code to construct DHCPv6 packets used by the server was enhanced
to support sending simple encapsulated options.  The only currently
defined option that is affected is the FQDN option.  [ISC-Bugs #29246]

Some issues were found in the handling of abandoned DHCPv4 leases.
Under some conditions an abandoned lease could be used much earlier
than expected and potentially without a ping check.  As part of the
patch we have added a new global configuration parameter "abandon-lease-time"
which determines how long a lease will be abandoned before it returns to
the available pool.  See the man page for the server configuration
for more information.  [ISC-Bugs #41815]

In the dhcrelay program we have now added the DHCPv4 options -iu and -id
to better control listening on interfaces.  The previous command to
specify an interface -i is still available and instructs the relay
to listen for any packets on that interface.  The -iu (upstream) option
will only listen for replies from servers or other relays while the -id
(downstream) option will only listen for requests from clients or other
relays.  By using these options (especially -iu for upstream interfaces)
the relay should avoid the duplication of packets it previously did.
[ISC-Bugs # 41547]

A bug in the interface handling code caused it to have problems with
interface names of exactly 15 characters.  This has been unnoticed in
the code for a while but with many people using docker and creating
15 character names it was discovered and is now fixed.  [ISC-Bugs #42226]

The following is the list of all changes for this release.

                        Changes since 4.1-ESV-R13

- Correct error message in relay to use remote id length instead
  of circuit id length.
  [ISC-Bugs #42556]

- Add support for including an encapsulated option in a response
  from the DHCPv6 server.  This allows the v6 FQDN option to be
  returned in responses.
  [ISC-Bugs #29246]

- Leases are now scrubbed of certain prior use information when pool
  re-balancing reassigns them from one FO peer to the other.  This
  corrects an issue where leases that were offered but ignored retained
  the client hostname from the original client. Thanks to Pavel Polacek,
  Jan Evangelista Purkyne University for reporting the issue.
  [ISC-Bugs #42008]

- Correct how the pick-first-value expression is written to a lease
  file.  Previously it was written as a concat expression due to
  a cut and paste error.
  [ISC-Bugs #42253]

- Added global configuration parameter, abandon-lease-time, which determines
  the amount of time a lease remains abandoned.  The default is 84600 seconds.
  Additionaly, the server now conducts a ping check (if ping checks are
  enabled) prior to offering an abandoned lease to client.  Our thanks to
  David Zych at University of Illinois for reporting the issue and working
  with us to produce a viable solution.
  [ISC-Bugs #41815]

- Correct handling of interface names during interface discovery. This
  addresses an issue where interface names of 15 characters in length
  could lead to crashes or interface recognition errors during startup
  of dhcpd, dhclient, and dhcrelay.
  [ISC-Bugs #42226]
  [ISC-Bugs #42310]

- Change dmalloc to use a size_t as the length argument to bring it
  in line with the call it will make to malloc().
  [ISC-Bugs #40843]

- If the failover socket can't be bound close it, otherwise if the
  user configures an incorrect address in the failover stanza the
  server will continue to open new sockets every 90 seconds until
  it runs out.
  [ISC-Bugs #42452]

- Add DHCPv4-mode, dhcrelay command line options, "-iu" and "-id", that
  allow interfaces to be upstream or downstream respectively.  Upstream
  interfaces will only accept and forward BOOTP replies, while downstream
  interfaces will only accept and forward BOOTP requests.
  [ISC-Bugs #41547]

- Clean up some memory references in the vendor-class construct.
  [ISC-Bugs #42984]

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