DHCP 4.3.0rc1 Release Notes
| Author: Sue Graves Reference Number: AA-01106 Views: 2300 Created: 2014-01-28 00:23 Last Updated: 2014-01-28 19:51
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Internet Systems Consortium DHCP Distribution
27 January 2014
The major "theme" for ISC DHCP 4.3.x was to update the support for
DHCPv6 to include several of the features that have been available
for DHCPv4. These include:
- Support the use of classes
- Support for on_commit, on_expiry and on_release statements
- Better logging of address assignments
- Support for using DHCPv6 relay options in expressions
This release also adds support for the standard DDNS as described in the
current RFCs as well as enhancing support for dynamically adding and removing
subclasses via OMAPI.
There are a number of DHCPv6 limitations and features missing in this
release, which will be addressed in the future:
- Only Solaris, Linux, FreeBSD, NetBSD, and OpenBSD are supported.
- DHCPv6 includes human-readable text in status code messages, in
English. A method to reconfigure or support other languages would
- The "host-identifier" option is limited to a simple token.
- The client and server can only operate DHCPv4 or DHCPv6 at a time,
not both. To use both protocols simultaneously, two instances of the
relevant daemon are required, one with the '-6' command line option.
For information on how to install, configure and run this software, as
well as how to find documentation and report bugs, please consult the
ISC DHCP uses standard GNU configure for installation. Please review the
output of "./configure --help" to see what options are available.
The system has only been tested on Linux, FreeBSD, and Solaris, and may not
work on other platforms. Please report any problems and suggested fixes to
ISC DHCP is open source software maintained by Internet Systems
Consortium. This product includes cryptographic software written
by Eric Young (firstname.lastname@example.org).
Changes since 4.2.0 (new features)
- If a client renews before 'dhcp-cache-threshold' percent of its lease
has elapsed (default 25%), the server will reuse the allocated lease
(provide a lease within the currently allocated lease-time) rather
than extend or renew the lease. This absolves the server of needing
to perform an fsync() operation on the lease database before reply,
which improves performance. [ISC-Bugs #22228]
Update this patch to support asynchronous DDNS. If the server is
attempting to do DDNS on a lease it should be updated and written to
disk even if that wouldn't be necessary due to the thresholding.
- The 'no available billing' log line now also logs the name of the last
matching billing class tried before failing to provide a billing.
- A problem with missing get_hw_addr function when --enable-use-sockets
was used is now solved on GNU/Linux, BSD and GNU/Hurd systems. Note
that use-sockets feature was not tested on those systems. Client and
server code no longer use MAX_PATH constant that is not defined on
GNU/Hurd systems. [ISC-Bugs #25979]
- Add a perl script in the contrib directory, dhcp-lease-list.pl, which
can parse v4 lease files and output the lease information in a more
human friendly manner. This was written by Christian Hammers with
some updates by vom and ISC. This is contributed code and is not
supported by ISC; however it may be useful to some users.
- Add support in v6 for on-commit, on-expire and on-release.
- Add support for using classes with v6.
- Update the DDNS code to current standards and allow for sharing
of DDNS entries between v4 and v6 clients. The new code is used
if the ddns-update-style is set to "standard", the older code is
still available if ddns-update-style is set to "interim". The
oldest DDNS code "ad-hoc" has been removed. Thanks to Thomas Pegeot
who submitted a patch for this issue. This patch is based on
that work with some modifications.
- Add a configuration option to the server to suppress using fsync().
Enabling this option will mean that fsync() is never called. This
may provide better performance but there is also a risk that a lease
will not be properly written to the disk after it has been issued
to a client and before the server stops. Using this option is
- Add some logging statements to indicate when the server is ready
to serve. One statement is emitted after the server has finished
reading its files and is about to enter the dispatch loop.
This is "Server starting service.".
The second is emitted when a server determines that both it and
its failover peer are in the normal state.
This is "failover peer <name>: Both servers normal."
- Add support for accessing options from v6 relays. The v6relay
statement allows the administrator to choose which relay to
use when searching for an option, see the dhcp-options man page
for a description. The host-identifer option has also been
updated to support the use of relay options see the dhcpd.conf
man page for a description.
- When doing DDNS if there isn't an appropriate zone statement attempt
to find a reasonable nameserver via a DNS resolver. This restores
some functionality that was lost in the transition to asynchronous
DDNS. Due to the lack of security and increase in fragility of the
system when using this feature we strongly recommend the use of
appropriate zone statements rather than using this functionality.
- Add support for specifying the address from which to send
DDNS updates on the DHCP server. There are two new options
"ddns-local-address4" and "ddns-local-address6" that each take
one instance of their respective address types.
- Add ignore-client-uids option in the server. This option causes
the server to not record a client's uid in its lease. This
violates the specification but may also be useful when a client
can dual boot using different client ids but the same mac address.
Thank you to Brian De Wolf at Cal Ply Pomona for the patch.
- Extend the DHCPINFORM processing to honor the subnet selection option
and take host declarations into account.
Thanks to Christof Chen for testing and submitting the patch.
- Extend the hardware expression to look into the lease structure
for a hardware address if there is no packet. This allows the
server to find the hardware address during on-expiry processing.
- Add definitions for some options that have been specified by the IETF.
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