ISC Dynamic Host Configuration Protocol (DHCP)

DHCP Distribution: Version 3.1.0

Version 3.1.x of the ISC DHCP Distribution includes the following major new features compared to its 3.0.x derivative:

• A significantly enhanced Failover protocol implementation, which:
  • Implements MAC Address Affinity to reduce the frequency of clients being assigned new IP addresses;
  • Supports the assignment of failover-protected addresses to legacy BOOTP clients;
  • Implements a dynamic lease reservation system that provides improved accounting of the use of fixed address assignments, by allocating fixed addresses out of the pool of dynamic leases; and
  • Further improves tools and reduces operator oversight necessary for maintaining a functioning system.
• Support for DHCP Leasequery, and the VIVCO/VIVSO options, which makes easy and comfortable integration with DOCSIS devices and the environment in which they are used.
• Management of class and subclass statements via OMAPI.
• Several server configuration options related to dynamic DNS behavior
• Other new configuration functions, including "execute()", which runs a shell command from within a dhcpd or dhclient configuration file

For a full list of new features added in this release, please observe the changes list directly following this section.

The release is located at http://ftp.isc.org/isc/dhcp/dhcp-3.1.0.tar.gz

For information on how to install, configure and run this software, as well as how to find documentation and report bugs, please consult the README file.

The Dynamic DNS Update support is a descendent of an implementation done by Lans Carstensen and Brian Dols at Rose-Hulman Institute of Technology, Jim Watt at Perkin-Elmer, Irina Goble at Integrated Measurement Systems, and Brian Murrell at BC Tel Advanced Communications. I'd like to express my thanks to all of these good people here, both for working on the code and for prodding me into improving it.

We've had successful builds on the following systems:

• AIX 5.1
• FreeBSD-5.2.1
• HP/UX 11.11i
• Linux-2.4
• MacOS X 10.3.
• SunOS 5.9 sun4u and i386
• Tru64 V5.1

Changes since 3.1.0rc1

• The parse warning that 'deny dyanmic bootp;' must be configured for failover protected subnets was removed.

Changes since 3.1.0b2

• Silenced compiler warnings on NetBSD
• Failover rebalance events no longer play ping pong with round errors (moving leases between free and back to backup where there are an odd number of leases).
• The 'pool' log line has been split into two messages, one before the rebalance run, and one after.
• Any queued BNDACKs are transmitted before transmitting new BNDUPDs. This enforces the correct sequence of events for the remote server processing these messages.
• Fixed a bug in which write_lease() might report a failure incorrectly
• supersede_lease() now requeues leases in their respective hardware address hash bucket. This mirrors client identifier behaviour.

Changes since 3.1.0b1

• Added -x option to dhclient, which triggers dhclient processes to exit gracefully without releasing leases first.
• Fixed a bug that caused OMAPI clients to freeze when opening lease objects.
• A new server config option "fqdn-reply" specifies whether the server should send out option 81 (FQDN). Defaults to "on". If set to "off", the FQDN option is not sent, even if the client requested it. This is needed because some clients misbehave otherwise. Thanks to Christof Chen at Allianz.
• Allow trace output files (-tf option) to be overwritten, rather than crashing dhcpd if the file already exists
• A bug was fixed that caused dhcpd to segfault if a pool was declared outside the scope of a subnet in dhcpd.conf.
• Some uninitialized values were repaired in dhcpleasequery.c that caused the server to abort.
• A new server config option, 'do-reverse-updates', has been added which causes the server to abstain from performing updates on PTR records. Thanks to a patch from Christof Chen at Allianz.
• A bug was repaired in subencapsulation support, where spaces separated by empty spaces would not get included.
• Corrected one situation where the column index variable might be used without being initialized, in expression-printing.
• Silenced several other compiler warnings.
• A bug in dhclient was repaired which caused it to send parameter request lists of 55 bytes in length no matter how long the declared PRL was.
• 'dhcp.c(3953): non-null pointer' has been repaired. This fixes a flaw wherein the DHCPv4 server may ignore a configured server-identifier.
• A flaw in failover startup sequences was repaired that sometimes left the primary DHCP server's pool rebalance schedules unscheduled.
• Corrected a flaw that broke encapsulated spaces included due to presence on the parameter request list.

Changes since 3.1.0a3

• The execute() statement has been changed from a "numeric expression" to an "executable statement", so that it can now be used with the syntax "execute(cmd, arg, ...)" rather than "eval(execute(cmd, arg, ...))".
• Some spelling fixes.

Changes since 3.1.0a2

• A bug was fixed where attempting to permit leasequeries results in a fatal internal error, "Unable to find server option 49".
• A bug was fixed in dhclient rendering the textual output form of the domain-search option syntax.

Changes since 3.1.0a1

• A bug in the FQDN universe that added FQDN codes to the NWIP universe's hash table was repaired.
• The servers now try harder to transmit pending binding updates when entering normal state.
• UPDREQ/UPDREQALL handling was optimized - it no longer dequeues and requeues all pending updates. This should reduce the number of spurious 'xid mismatch' log messages.
• An option definition referencing leak was fixed, which resulted in early termination of dhclient upon the renewal event.
• Some default hash table sizes were tweaked, some upwards, some downwards. 3.1.0a1's tables resulted in a reduction in default server memory use. The new selected values provide more of a zero sum (increasing the size of tables likely to be populated, decreasing the size of tables unlikely).
• Lease structures appear in three spearate hashes: by IP address, by UID, and by hardware address. One type of table was used for all three, and improvements to IP address hashing were applied to all three (so UID and hardware addresses were treated like 4-byte integers). There are now two types of tables, and the uid/hw hashes use functions more appropriate to their needs.
• The max-lease-misbalance percentage no longer causes scheduled rebalance runs to be skipped: it still governs the schedule, but every scheduled run will attempt balance.
• A segfault bug in recursive encapsulation support has been corrected.

Changes since 3.0 (New Features)

• A workaround for certain STSN servers that send a mangled domain-name option was introduced for dhclient. The client will now accept corrupted server responses, if they contain a valid DHCP_MESSAGE_TYPE (OFFER, ACK, or NAK). The server will continue to not accept corrupt client packets.
• Support for 'reserved' (psuedo-static) and BOOTP leases via failover was introduced.
• Support for adding, removing, and managing class and subclass statements via OMAPI.
• The failover implementation was updated to comply with revision 12 of the protocol draft.
• 'make install' now creates the initial zero-length dhcpd.leases file if one does not already exist on the system.
• RFC3942 compliance, site-local option spaces start at 224 now, not 128.
• The Load Balance Algorithm was misimplemented. The current implementation matches RFC 3074.
• lcase() and ucase() configuration expressions have been added which adjust their arguments from upper to lower and lower to upper cases respectively. Thanks to a patch from Albert Herranz.
• The dhclient 'reject ...;' statement, which rejects leases given by named server-identifiers, now permits address ranges to be specified in CIDR notation. Thanks to a patch from David Boyce.
• The subnet-mask option is now supplied by default, but at lowest priority. This helps a small minority of clients that provide parameter request lists, but do not list the subnet-mask option because they were designed to interoperate with a server that behaves in this manner.
• The FQDN option is similarly supplied even if it does not appear on the parameter request list, but not to the exclusion of options that do appear at the parameter request list. Up until now it had ultimate priority over the client's parameter request list.
• Varying option space code and length bit widths (8/16/32) are now supported. This is a milestone in achieving RFC 3925 "VIVSO" and DHCPv6 support.
• A new common (server or client) option, 'db-time-format local;', has been added which prints the local time in /var/db/dhcpd.leases rather than UTC. Thanks to a patch from Ken Lalonde.
• Some patches to improve DHCP Server startup speed from Andrew Matheson have been incorporated.
• Failover pairs now implement 'MAC Affinity' on leases moving from the active to free states. Leases that belonged to the failover secondary are moved to BACKUP state rather than FREE upon exiting EXPIRED state. If lease rebalancing must move leases, it tries first to move leases that belong to the peer in need.
• The server no longer sends POOLREQ messages unless the pool is severely misbalanced in the peer's favor (see 'man dhcpd.conf' for more details).
• Pool rebalance events no longer happen upon successfully allocating a lease. Instead, they happen on a schedule. See 'man dhcpd.conf' for the min-balance and max-balance statements for more information.
• The DHCP Relay Agent Information Option / Link Selection Sub-Option is now supported. (See RFC3527 for details).
• A new DDNS related server option, update-conflict-detection, has been added. If this option is enabled, dhcpd will perform normal DHCID conflict resolution (the default). If this option is disabled, it will instead trust the assigned name implicitly (removing any other bindings on that name). This option has not been made available in dhclient.
• In those cases where the DHCP software manufactures an IP header (to transmit via bpf, lpf, etc), the IP TTL the software selects has been increased from 16 to 128. This is intended to match Microsoft Windows DHCP Client behaviour, to increase compatibility.
• 'ignore client-updates;' now has behaviour that is different from 'deny client-updates;'. The client's request is not truly ignored, rather it is encouraged. Should this value be configured, the server updates DNS as though client-updates were set to 'deny'. That is, it enters into DNS whatever it is configured to do already, provided it is configured to. Then it sends a response to the client that lets the client believe it is performing client updates (which it will), probably for a different name. In essence, this lets the client do as it will, ignoring this aspect of their request.
• Support for compressed 'domain name list' style DHCP option contents, and in particular the domain search option (#119) was added.
• The DHCP LEASEQUERY protocol as defined in RFC4388 is now implemented. LEASEQUERY lets you query the DHCP server for information about a lease, using either an IP address, MAC address, or client identifier. Thanks to a patch from Justin Haddad.
• DHCPD is now RFC2131 section 4.1 compliant (broadcast to all-ones ip and ethernet mac address) on the SCO platform specifically without any strange ifconfig hacks. Many thanks go to the Kroger Co. for donating the hardware and funding the development.
• A new common configuration executable statement, execute(), has been added. This permits dhcpd or dhclient to execute a named external program with command line arguments specified from other configuration language. Thanks to a patch written by Mattias Ronnblom, gotten to us via Robin Breathe.
• A new dhcp server option 'adaptive-lease-time-threshold' has been added which causes the server to substantially reduce lease-times if there are few (configured percentage) remaining leases. Thanks to a patch submitted from Christof Chen.
• Encapsulated option spaces within encapsulated option spaces is now formally supported.

Changes since 3.0.5rc1

• A bug was repaired in fixes to the dhclient, which saught to run the dhclient-script with the 'EXPIRE' state should it receive a NAK in response to a REQUEST. The client now iterates the PREINIT state after the EXPIRE state, so that interfaces that might be configured 'down' can be brought back 'up' and initialized.
• DHCPINFORM handling for clients that properly set ciaddr and come to the server via a relay aget has been repaired.

Changes since 3.0.4

• A warning that host statements declared within subnet or shared-network scopes are actually global has been added.
• The default minimum lease time (if min-lease-time was not specified) was raised from 0 to 300. 0 is not thought to be sensible, and is known to be damaging.
• Added additional fatal error sanity checks surrounding lease binding state count calculations (free/active counts used for failover pool balancing).
• Some time value size fixes in 3.0.4 brought on from FreeBSD /usr/ports were misapplied to server values rather than client values. The server no longer advertises 8-byte lease-time options when on 64-bit platforms.
• A bug where leases not in ACTIVE state would get billed to billed classes (classes with lease limitations) was fixed. Non-active leases OFFERed to clients are no longer billed (but billing is checked before offering).
• The dhcpd.conf.5 manpage was updated in regard to the ddns-domainname configuration option - the default configuration and results should be more clear now.
• If the dhclient were to receive a DHCPNAK while it was in the RENEW state (and consequently, had an active, 'bound' address and related configuration options), it would fail to 'tear down' this information before proceeding into INIT state. dhclient now iterates the dhclient- script with the 'EXPIRE' action to cause these teardowns prior to entering INIT state. Thanks to a patch from Chris Zimmerman.
• The omapi.1 manpage had some formatting errors repaired thanks to a patch from Yoshihiko Sarumaru.
• A few lines of code that were failover-specific were moved within #if defined() clauses so that compilation without failover could be made possible.
• The log message emitted when the 'leased-address' value was not available in dhcpd.conf "executable statements" has been updated to be more helpful. Manpage information for this value has also been updated.
• Abandoned or dissociated (err condition) leases now remove any related dynamic dns bindings. Thanks to a patch from Patrick Schoo.
• Attempting to write a new lease file to replace a corrupt (due to encountering non-retryable errors during writing) lease file should no longer result in an infinite recursion.
• Host declaration hardware addresses and client identifiers may only be configured once. dhcpd will now fail to load config files that specify multiple identifiers (previous versions would silently over-ride the value with the later configured value).

Changes since 3.0.4b3

• Some manual pages were clarified pursuant to discussion on the dhcp-server mailing list.

Changes since 3.0.4b2

• Null-termination sensing for certain clients that unfortunatley require it in DHCPINFORM processing was repaired.
• The host-name option and a few others were moved from "X" format to "t" format to be compatible with new NULL handling functions.
• DHCPINFORM processing is a little more careful about return addressing its responses, or if responding via a relay. The INFORM related messages also log the 'effective client ip address' rather than the client's supplied ciaddr (since some clients produce null ciaddrs).
• The server was inappropriately sending leases to the RESET state in the event that multiple active leases were found to match a singly-identified client. This was changed to RELEASED (by accepting a different, ACTIVE binding, the client is implicitly releasing its lease). This repairs a bug wherein secondary servers in failover pairs detecting this condition move leases to RESET, and primaries refuse to accept that state transition (properly).
• The memset-after-dmalloc() changes made in 3.0.4b1 have been backed out.

Changes since 3.0.4b1

• Command line parsing in omshell was repaired - it no longer closes STDIN after reading one line.
• The resolver library no longer closes the /etc/resolv.conf file descriptor it opened twice.
• Changes to trailing NULL removal in 't' option-atoms has been rethought, it now includes 'd' (domain name) types, and tries hard not to rewind an option beyond the start of the text field it is un-terminating.

Changes since 3.0.3

• A DDNS update handling function was misusing the DNS error codes, rather than the internal generic result enumeration. The result is a confusing syslog line, logging the wrong condition.
• The DHCP Server was not checking pool balance in the case where it brought a non-ACTIVE lease out of storage for a client that was returning to use a lease it once had long ago, and had since expired.
• Failover peers no longer bother to look for free leases to allocate when they already found the client's ACTIVE lease. DISCOVERs are load balanced wether freely-allocated or not, unless the server doubts the peer has leases to allocate.
• Fixed a bug in dhcrelay agent addition code that suppressed trailing PAD options - it was suppressing only one trailng PAD option, rather than the entire block of them.
• Fixed some unlikely overlapping-region memcpy() bugs in dhcrelay agent option addition and stripping code. Added a few sanity checks.
• Added some sanity checks to OMAPI connection/authentication code.
• dmalloc() memset()'s the non-debug (data) portion of the allocated memory to zero. Code that memset()'s the result returned by dmalloc() to zero is redundant. These redundancies were removed.
• Some type declaration corrections to u_int16_t were made in common/tr.c (Token Ring support) thanks to a patch from Jason Vas Dias at RedHat.
• A failover bug that was allowing leases that EXPIRED or were RELEASED where tsfp and tstp are identical timestamps to languish in these transitional states has been repaired. As a side effect, lease databases should be kept more consistent overall, not just for these transitional states.
• If the lease db is deleted out from under the daemon, and it moves to rewrite the db, it will go ahead with the operation and move the new db into place once it detects the old db does not exist.
• dhclient now ignores IRDA, SIT, and IEEE1394 network interfaces, as it is either nonsensical or (in the case of IEEE1394) is not known to support these interfaces. Thanks to Marius Gedminas and Andrew Pollock of Debian.
• Some previously undocumented reasons for dhclient-script invoking has been doucmented in the dhclient-script.8 manpage.
• Failover potential expiry calculations (TSTP) have been corrected. Results should be substantially more consistent, and proper given the constraints.
• Adjusted lease state validation checks in potential-conflict, to account for possible clock skew similarly to normal state, and several previously illegal transitions were made legal (ex: active->released).
• An impossible sanity check was removed from omapi/buffer.c, thanks to a patch from 'infamous42md'.
• An OMAPI host/network byte order problem in lease time values has been repaired.
• Several minor bugs, largely relating to treating 8-byte time values as 4-byte entities, have been repaired after careful review of the FreeBSD ports collection's patch set. Thanks to the nameless entities who have contributed to the FreeBSD ports.
• When writing a trace file, the file is now created with permissions 0600, to help administrators avoid accidentally publicising sensitive config data.
• The calculation of the maximum size of DHCP packets no longer includes Ethernet framing overhead. The result is that the 'Maximum Message Size' option advertised by clients, or the default value 576, is no longer reduced by 14 bytes, and instead directly reflects the IP level MTU (and the default, minimum allowed IP MTU of 576).
• The special status of RELEASED/EXPIRED/RESET leases when a server is operating in partner-down was fixed. It no longer requires a lease be twice the MCLT beyond STOS to 'reallocate', and the expiry event to turn these into FREE leases without peer acknowledgement (after STOS+MCLT) has been repaired.
• Compilation on older Solaris systems (lacking /usr/include/sys/int_types.h) has been repaired.
• "append"ing a string onto the end of a "t" type option (such as the domain-name field) that had been improperly NULL-terminated by the DHCP server will no longer result in a truncated string containing only the option from the server, and not the expected appended value. Thanks to a patch from Jason Vas Dias at RedHat.
• File handlers on configuration state (config files and lease dbs) should be treated consistently, regardless of wether TRACING is defined or not.
• The linux build environment has had some minor improvements - better sensing of 64-bit pointer sizes (only used for establishing an icmp_id), and corrections to #if operators regarding LINUX_MAJOR should it ever move to 3.[01].x.
• The server now tries harder to survive the condition where it is unable to open a new lease file to rewrite the lease state database.

Changes since 3.0.3b3

• dhclient.conf documentation for interface {} was updated to reflect recent discussion on the dhcp-hackers mailing list.
• In response to reports that the software does not compile on GCC 4.0.0, -Werror was removed from Makefile.conf for all platforms that used it. We will address the true problem in a future release; this is a temporary workaround.

Changes since 3.0.3b2

• An error in code changes introduced in 3.0.3b2 was corrected, which caused static BOOTP clients to receive random addresses.

Changes since 3.0.3b1

• A bug was fixed in BOOTPREQUEST handling code wherein stale references to host records would be left behind on leases that were not allocated to the client currently booting (eg in the case where the host was denied booting).
• The dhcpd.conf.5 manpage was updated to be more clear in regards to multiple host declarations (thanks to Vincent McIntyre). 'Interim' style dynamic updates were also retouched.

Changes since 3.0.2

• A bug was fixed where a server might load balance a DHCP REQUEST to its peer after already choosing not to load balance the preceeding DISCOVER. The peer cannot allocate the originating server's lease.
• In the case where a secondary server lost its stable storage while the primary was still in communications-interrupted, and came back online, the lease databases would not be fully transferred to the secondary. This was due to the secondary errantly sending an extra UPDREQ message when the primary made its state transition to PARTNER-DOWN known.
• The package will now compile cleanly in gcc 3.3 and 3.4. As a side effect, lease structures will be 9 bytes smaller on all platforms. Thanks to Jason Vas Dias at Redhat.
• Interface discovery code in DISCOVER_UNCONFIGURED mode is now properly restricted to only detecting broadcast interfaces. Thanks to a patch from Jason Vas Dias at RedHat.
• decode_udp_ip_header was changed so that the IP address was copied out to a variable, rather than referenced by a pointer. This enforces 4-byte alignment of the 32-bit IP address value. Thanks to a patch from Dr. Peter Poeml.
• An incorrect log message was corrected thanks to a patch from Dr. Peter Poeml.
• A bug in DDNS was repaired, where if the server's first DDNS action was a DDNS removal rather than a DDNS update, the resolver library's retransmit timer and retry timer was set to the default, implying a 15 second timeout interval. Which is a little excessive in a synchronous, single-threaded system. In all cases, ISC DHCP should now hold fast to a 1-second timeout, trying only once.
• The siaddr field was being improperly set to the server-identifier when responding to DHCP messages. RFC2131 clarified the siaddr field as meaning the 'next server in the bootstrap process', eg a tftp server. The siaddr field is now left zeroed unless next-server is configured.
• mockup_lease() could have returned in an error condition (or in the condition where no fixed-address was found matching the shared network) with stale references to a host record. This is probably not a memory leak since host records generally never die anyway.
• A bug was repaired where failover servers would let stale client identifiers persist on leases that were reallocated to new clients not sending an id.
• Binding scopes ("set var = value;") are now removed from leases allocated by failover peers if the lease had expired. This should help reduce the number of stale binding scopes on leases.
• A small memory leak was closed involving client identifiers larger than 7 bytes, and failover.
• Configuring a subnet in dhcpd.conf with a subnet mask of 32 bits might cause an internal function to overflow heap. Thanks to Jason Vas Dias at Redhat.
• Some inconsistencies in treating numbers that the lexer parsed as 'NUMBER' or 'NUMBER_OR_NAME' was repaired. Hexadecimal parsing is affected, and should work better.
• In several cases, parse warnings were being issued before the lexical token had been advanced to the token whose value was causing an error... causing parse warnings to claim the problem is on the wrong token.
• Host declarations matching on client identifier for dynamic leases will no longer match fixed-address host declarations (this is now identical to behaviour for host records matching on hardware address).

Changes since 3.0.2rc3

• A previously undocumented configuration directive, 'local-address', was documented in the dhcpd.conf manpage.

Changes since 3.0.2rc2

• Two varaibles introduced in 3.0.2b1 were used without being initialized in the case where neither the FILE nor SNAME fields were available for overloading. This was repaired.
• A heretofore believed to be impossible corner case of the option overloading implementation turned out to be possible ("Unable to sort overloaded options after 10 tries."). The implementation was reworked to consider the case of an option so large it would require more than three chunks to fit.
• Many other instances of variables being used without being initialized were repaired.
• An uninitialized variable in omapi_io_destroy() led to the discovery that this function may result in orphaned pointers (and hence, a memory leak).

Changes since 3.0.2rc1

• allocate_lease() was rewritten to repair a bug in which the server would try to allocate an ABANDONED lease when FREE leases were available.

Changes since 3.0.2b1

• Some dhcp-eval.5 manpage formatting was repaired.

Changes since 3.0.1

• A bug was fixed in the server's 'option overloading' implementation, where options loaded into the 'file' and 'sname' packet fields were not aligned precisely as rfc2131 dictates.
• The FreeBSD client script was changed to support the case where a domain name was not provided by the server.
• A memory leak in 'omshell' per each command line parsed was repaired, thanks to a patch from Jarkko Torppa.
• Log functions writing to stderr were adjusted to use the STDERR_FILENO system definition rather than '2'. This is a no-op for 90% of platforms.
• One call to trace_write_packet_iov() counted the number of io vectors incorrectly, causing inconsistent tracefiles. This was fixed.
• Some expression parse failure memory leaks were closed.
• A host byte order problem in tracefiles was repaired.
• Pools configured in DHCPD for failover possessing permission lists that previously were assumed to not include dyanmic bootp clients are now a little more pessimistic. The result is, dhcpd will nag you about just about most pools that possess a 'allow' statement with no 'deny' that would definitely match a dynamic bootp client.
• The 'ddns-update-style' configuration warning bit now insists that the configuration be globally scoped.
• Two memory leaks in dhclient were closed thanks to a patch from Felix Farkas.
• Some minor but excellently pedantic documentation errors were fixed thanks to a patch from Thomas Klausner.
• Bugs in operator precedence in executable statements have been repaired once again. More legal syntaxes should be parsed legally.
• Failing to initialize a tracefile for any reason if a tracefile was specified is now a fatal error. Thanks to a patch from Albert Herranz.
• Corrected a bug in which the number of leases transferred as calculated by the failover primary and sent to peers in POOLRESP responses may be incorrect. This value is not believed to be used by other failover implementations, excepting perhaps as logged information.
• Corrected a bug in which 'dhcp_failover_send_poolresp()' was in fact sending POOLREQ messages instead of POOLRESP mesasges. This message was essentially ignored since failover secondaries effectively do not respond to POOLREQ messages.
• Type definitions for various bitwidths of integers in the sunos5-5 build of ISC DHCP have been fixed. It should compile and run more easily when built in 64-bit for this platform.
• "allow known-clients;" is now a legal syntax, to avoid confusion.
• If one dhcp server chooses to 'load balance' a request to its failover peer, it first checks to see if it believes said peer has a free lease to allocate before ignoring the DISCOVER.
• log() was logging a work buffer, rather than the value returned by executing the statements configured by the user. In some cases, the work buffer and the intended results were the same. In some other cases, they were not. This was fixed thanks to a patch from Gunnar Fjone and directconnect.no.
• Compiler warnings for some string type conversions was fixed, thanks to Andreas Gustafsson.
• The netbsd build environments were simplified to one, in which -Wconversion is not used, thanks to Andreas Gustafsson.
• How randomness in the backoff-cutoff dhclient configuration variable is implemented was better documented in the manpage, and the behaviour of dhclient in REQUEST timeout handling was changed to match that of DISCOVER timeout handling.
• Omapi was hardened against clients that pass in null values, thanks to a patch from Mark Jason Dominus.
• A bug was fixed in dhclient that kept it from doing client-side ddns updates. Thanks to a patch from Andreas Gustafsson, which underwent some modification after review by Jason Vas Dias.
• Failover implementations disconnected due to the network between them (rather than one of the two shutting down) will now try to re-establish the failover connection every 5 seconds, rather than to simply try once and give up until one of them is restarted. Thanks to a patch from Ulf Ekberg from Infoblox, and field testing by Greger V. Teigre which led to an enhancement to it.
• A problem that kept DHCP Failover secondaries from tearing down ddns records was repaired. Thanks to a patch from Ulf Ekberg from Infoblox.
• 64bit pointer sizes are detected properly on FreeBSD now.
• A bug was repaired where the DHCP server would leave stale references to host records on leases it once thought about offering to certain clients. The result would be to apply host and 'known' scopes to the wrong clients (possibly denying booting). NOTE: The 'mis-host' patch that was being circulated as a workaround is not the way this bug was fixed. If you were a victim of this bug in 3.0.1, you are cautioned to proceed carefully and see if it fixes your problem.
• A bug was repaired in the server's DHCPINFORM handling, where it tried to divine the client's address from the source packet and would get it wrong. Thanks to Anshuman Singh Rawat.
• A log message was introduced to help illuminate the case where the server was unable to find a lease to assign to any BOOTP client. Thanks to Daniel Baker.
• A minor dhcpd.conf.5 manpage error was fixed.

Changes since 3.0.1rc14

• The global variable 'cur_time' was centralized and is now uniformly of a type #defined in system-dependent headers. It had previously been defined in one of many places as a 32-bit value, and this causes mayhem on 64-bit big endian systems. It probably wasn't too healthy on little endian systems either.
• A printf format string error introduced in rc14 was repaired.
• AIX system-dependent header file was altered to only define NO_SNPRINTF if the condition used to #ifdef in vsnprintf in AIX' header files is false.
• The Alpha/OSF system-dependent header file was altered to define NO_SNPRINTF on OS revisions older than 4.0G.
• omapip/test.c had string.h added to its includes.

Changes since 3.0.1rc13

• CAN-2004-0460 - CERT VU#317350: Five stack overflow exploits were closed in logging messages with excessively long hostnames provided by the clients. It is highly probable that these could have been used by attackers to gain arbitrary root access on systems using ISC DHCP 3.0.1 release candidates 12 or 13. Special thanks to Gregory Duchemin for both finding and solving the problem.
• CAN-2004-0461 - CERT VU#654390: Once the above was closed, an opening in log_*() functions was evidented, on some specific platforms where vsnprintf() was not believed to be available and calls were wrapped to sprintf() instead. Again, credit goes to Gregory Duchemin for finding the problem. Calls to snprintf() are now linked to a distribution-local snprintf implementation, only in those cases where the architecture is not known to provide one (see includes/cf/[arch].h). If you experience linking problems with snprintf/vsnprintf or 'isc_print_' functions, this is where to look. This vulnerability did not exist in any previously published version of ISC DHCP.
• Compilation on hpux 11.11 was repaired.
• 'The cross-compile bug fix' was backed out.

Changes since 3.0.1rc12

• Fixed a bug in omapi lease lookup function, to form the hardware address for the hash lookup correctly, thanks to a patch from Richard Hirst.
• Fixed a bug where dhcrelay was sending relayed responses back to the broadcast address, but with the source's unicast mac address. Should now conform to rfc2131 section 4.1.
• Cross-compile bug fix; use $(AR) instead of ar. Thanks to Morten Brorup.
• Fixed a crash bug in dhclient where dhcpd servers that do not provide renewal times results in an FPE. As a side effect, dhclient can now properly handle 0xFFFFFFFF (-1) expiry times supplied by servers. Thanks to a patch from Burt Silverman.
• The 'ping timeout' debugs from rc12 were removed to -DDEBUG only, and reformatted to correct a compilation error on solaris platforms.
• A patch was applied which fixes a case where leases read from the leases database do not properly over-ride previously read leases.
• dhcpctl.3 manpage was tweaked.

Changes since 3.0.1rc11

• A patch from Steve Campbell was applied with minor modifications to permit reverse dns PTR record updates with values containing spaces.
• A patch from Florian Lohoff was applied with some modifications to dhcrelay. It now discards packets whose hop count exceeds 10 by default, and a command-line option (-c) can be used to set this threshold.
• A failover bug relating to identifying peers by name length instead of by name was fixed.
• Delcaring failover configs within shared-network statements should no longer result in error.
• The -nw command line option to dhclient now works.
• Thanks to a patch from Michael Richardson: - Some problems with long option processing have been fixed. - Some fixes to minires so that updates of KEY records will work.
• contrib/ms2isc was updated by Shu-Min Chang of the Intel Corporation. see contrib/ms2isc/readme.txt for revision notes.
• Dhclient no longer uses shell commands to kill another instance of itself, it sends the signal directly. Thanks to a patch from Martin Blapp.
• The FreeBSD dhclient-script was changed so that a failure to write to /etc/resolv.conf does not prematurely end the script. This keeps dhclient from looping infinitely when this is the case. Thanks to a patch from Martin Blapp.
• A patch from Bill Stephens was applied which resolves a problem with lease expiry times in failover configurations.
• A memory leak in configuration parsing was closed thanks to a patch from Steve G.
• The function which discovers interfaces will now skip non-broadcast or point-to-point interfaces, thanks to a patch from David Brownlee.
• Options not yet known by the dhcpd or dhclient have had their names changed such that they do not contain # symbols, in case they should ever appear in a lease file. An option that might have been named "#144" is now "unknown-144".
• Another patch from Bill Stephens which allows the ping-check timeout to be configured as 'ping-timeout'. Defaults to 1.

Changes since 3.0.1rc10

• Potential buffer overflows in minires repaired.
• A change to the linux client script to use /bin/bash, since /bin/sh may not be bash.
• Some missing va_end cleanups thanks to a patch from Thomas Klausner.
• A correction of boolean parsing syntax validation - some illegal syntaxes that worked before are now detected and produce errs, some legal syntaxes that errored before will now work properly.
• Some search-and-replace errors that caused some options to change their names was repaired.
• Shu-min Chang of the Intel corporation has contributed a perl script and module that converts the MS NT4 DHCP configuration to a ISC DHCP3 configuration file.
• Applied the remainder of the dhcpctl memory leak patch provided by Bill Squier at ReefEdge, Inc. (groo@reefedge.com).
• Missing non-optional failover peer configurations will now result in a soft error rather than a null dereference.

Changes since 3.0.1rc9

• A format string was corrected to fix compiler warnings.
• A number of spelling corrections were made in the man pages.
• The dhclient.conf.5 man page was changed to refer to do-forward-updates rather than a configuration option that doesn't exist.
• A FreeBSD-specific bug in the interface removal handling was fixed.
• A Linux-specific Token Ring detection problem was fixed.
• Hashes removed from as-yet-unknown agent options, having those options appear in reality before we know about them will no longer produce self-corrupting lease databases.
• dhclient will use the proper port numbers now when using the -g option.
• A order-of-operations bug with 2 match clauses in 1 class statement is fixed thanks to a patch from Andrew Matheson.
• Compilation problems on Solaris were fixed.
• Compilation problems when built with DEBUG or DEBUG_PACKET were repaired.
• A fix to the dhcp ack process which makes certain group options will be included in the first DHCPOFFER message was made thanks to a patch from Ling Gou.
• A few memory leaks were repaired thanks to patches from Bill Squier at ReefEdge, Inc. (groo@reefedge.com).
• A fix for shared-networks that sometimes give clients options for the wrong subnets (in particular, 'option routers') was applied, thanks to Ted Lemon for the patch.
• Omshell's handling of dotted octets as values was changed such that dots one after the other produce zero values in the integer string.

Changes since 3.0.1rc8

• Fix a format string vulnerability in the server that could lead to a remote root compromise (discovered by NGSEC Research Team, www.ngsec.com).
• Add additional support for NetBSD/sparc64.
• Fix a bug in the command-line parsing of the client. Also, resolve a memory leak.
• Add better support for shells other than bash in the Linux client script.
• Various build fixes for modern versions of FreeBSD and Linux.
• Fix a bad bounds check when printing binding state names.
• Clarify documentation about fixed-address and multiple addresses.
• Fix a typo in the authoritative error message.
• Make a log entry when we can't write a billing class.
• Use conversion targets that are the right size on all architectures.
• Increment the hop count when relaying.
• Log a message when lease state is changed through OMAPI.
• Don't rerun the shared_network when evaluating the pool.
• Fix a reversed test in the parser.
• Change the type of rbuf_max.
• Make FTS_LAST a manifest constant to quiet warnings.

Changes since 3.0.1rc7

• Fix two compiler warnings that are generated when compiling on Solaris with gcc. These stop the build, even though they weren't actually errors, because we prefer that our builds generate no warnings.

Changes since 3.0.1rc6

• Don't allow a lease that's in the EXPIRED, RELEASED or RESET state to be renewed.
• Implement lease stealing for cases where the primary has fewer leases than the secondary, as called for by the standard.
• Add a fudge factor to the lease expiry acceptance code, (suggested by Kevin Miller of CMU).
• Fix a bug in permit_list_match that made it much too willing to say that two permit lists matched.
• Unless DEBUG_DNS_UPDATES is defined, print more user-friendly (and also more compact) messages about DNS updates.
• Fix a bug in generating wire-format domain names for the FQDN option.
• Fix a bug where the FQDN option would not be returned if the client requested it, contrary to the standard.
• On Darwin, use the FreeBSD DHCP client script.
• On NetBSD/sparc, don't check for casting warnings.
• Add a flag in the DHCP client to disable updating the client's A record when sending an FQDN option indicating that the client is going to update its A record.
• In the client, don't attempt a DNS update until one second after configuring the new IP address, and if the update times out, keep trying until a response, positive or negative, is received from the DNS server.
• Fix an uninitialized memory bug in the DHCP client.
• Apply some FreeBSD-specific bug fixes suggested by Murray Stokely.
• Fix a bug in ns_parserr(), where it was returning the wrong sort of result code in some cases (suggested by Ben Harris of the NetBSD project).
• Fix a bug in is_identifier(), where it was checking against EOF instead of the END_OF_FILE token (also suggested by Ben Harris).
• Fix a bug where if an option universe contained no options, the DHCP server could dump core (Walter Steiner).
• Fix a bug in the handling of encapsulated options.
• Fix a bug that prevented NWIP suboptions from being processed.
• Delete the FTS_BOOTP and FTS_RESERVED states and implement them as modifier flags to the FTS_ACTIVE state, as called for in the failover protocol standard.
• Fix bugs in the pool merging code that resulted in references and dereferences of null pointers. This bug had no impact unless the POINTER_DEBUG flag was defined.
• In the server, added a do-forward-updates flag that can be used to disable forward updates in all cases, so that sites that want the clients to take sole responsibility for updating their A record can do so.
• Make it possible to disable optimization of PTR record updates.

Changes since 3.0.1rc5

• Include some new documentation and changes provided by Karl Auer.
• Add a workaround for some Lexmark printers that send a double-NUL- terminated host-name option, which would break DNS updates.
• Fix an off-by-one error in the MAC-address checking code for DHCPRELEASE that was added in 3.0.1rc5.
• Fix a bug where client-specific information was not being discarded from the lease when it expired or was released, resulting in problems if the lease was reallocated to a different client.
• If more than one allocation pool is specified that has the same set of constraints as another allocation pool on the same shared network, merge the two pools.
• Don't print an error in fallback_discard, since this just causes confusion and does not appear to be helping to encourage anyone to fix this bug.

Changes since 3.0.1rc4

• Fix a bug that would cause the DHCP server to spin if asked to parse a certain kind of incorrect statement.
• Fix a related bug that would prevent an error from being reported in the same case.
• Additional documentation.
• Make sure that the hardware address matches the lease when processing a DHCPRELEASE message.

Changes since 3.0.1rc3

• A minor bug fix in the arguments to a logging function call.
• Documentation update for dhcpd.conf.

Changes since 3.0.1rc2

• Allow the primary to send a POOLREQ message. This isn't what the current failover draft says to do, so we may have to back it out if I can't get the authors to relent, but the scheme for balancing that's specified in the current draft seems needlessly hairy, so I'm floating a trial balloon. The rc1 code did not implement the method described in the draft either.

Changes since 3.0.1rc1

• Treat NXDOMAIN and NXRRSET as success when we are trying to delete a domain or RRSET. This allows the DHCP server to forget about a name it added to the DNS once it's been removed, even if the DHCP server wasn't the one that removed it.
• Install defaults for failover maximum outstanding updates and maximum silent time. This prevents problems that might occur if these values were not configured.
• Don't do DDNS deletes if ddns-update-style is none.
• Return relay agent information options in DHCPNAK. This prevents DHCPNAK messages from being dropped when the relay agent information option contains routing information.
• Fix a problem where coming up in recover wouldn't result in an update request being sent.
• Add some more chatty messages when we start a recovery update and when it's done.
• Fix a possible problem where some state might have been left around after the peer lost contact and regained contact about how many updates were pending.
• Don't nix a lease update because of a lease conflict. This test has never (as far as I know) prevented a mistake, and it appears to cause problems with failover.
• Add support in rc history code for keeping a selective history, rather than a history of all references and dereferences. This code is only used when extensive additional debugging is enabled.

Changes since 3.0

• Make allocators for hash tables. As a side effect, this fixes a memory smash in the subclass allocation code.
• Fix a small bug in omshell where if you try to close an object when no object is open, it dumps core.
• Fix an obscure coredump that could occur on shutdown.
• Fix a bug in the recording of host declaration rubouts in the lease file.
• Fix two potential spins in the host deletion code.
• Fix a core dump that would happen if an application tried to update a host object attribute with a null value.

Changes since 3.0p1

• SECURITY FIX: CA-2003-01. A potential flaw in the minires resolver library packaged with ISC DHCP was repaired.

Changes since 3.0

• SECURITY FIX: CA-2002-12. A format string vulnerability was repaired.

Changes since 3.0 Release Candidate 12

• Fix a memory leak in the expression evaluation code.
• Fix an obscure core dump.
• Print a couple of new warnings when parsing the configuration file when crucial information is left out.
• Log "no free leases" as an error.
• Documentation updates.

Changes since 3.0 Release Candidate 11

• Always return a subnet selection option if one is sent.
• Fix a warning that was being printed because an automatic data structure wasn't zeroed.
• Fix some failover state transitions that were being handled incorrectly.
• When supersede_lease is called on a lease whose end time has already expired, but for which a state transition has not yet been done, do a state transition. This fixes the case where if the secondary allocated a lease to a client and the lease "expired" while the secondary was in partner-down, no expiry event would actually happen, so the lease would remain active until the primary was restarted.

Changes since 3.0 Release Candidate 10

• Fix a bug that was preventing released leases from changing state in failover-enabled pools.
• Fix a core dump in the client identifier finder code (for host declarations).
• Finish fixing a bug where bogus data would sometimes get logged to the dhclient.leases file because it was opened as descriptor 2.
• Fix the linux dhclient-script according to suggestions made by several people on the dhcp-client mailing list.
• Log successful DNS updates at LOG_INFO, not LOG_ERROR.
• Print an error message and refuse to run if a failover peer is defined but not referenced by any pools.
• Correct a confusing error message in failover.

Changes since 3.0 Release Candidate 9

• Fix a bug in lease allocation for Dynamic BOOTP clients.

Changes since 3.0 Release Candidate 8 Patchlevel 2

• Fix a bug that prevented update-static-leases from working.
• Document failover-state OMAPI object.
• Fix a compilation error on SunOS 4.

Changes since 3.0 Release Candidate 8 Patchlevel 1

• Fix a parsing bug that broke dns updates (both interim and ad-hoc). This was introduced in rc8pl1 as an unintended result of the memory leakage fixes that were in pl1.
• Fix a long-standing bug where the server would record that an update had been done for a client with no name, even though no update had been done, and then when the client's lease expired the deletion of that nonexistent record would time out because the name was the null string.
• Clean up the omshell, dhcpctl and omapi man pages a bit.

Changes since 3.0 Release Candidate 8

• Fix a bug that could cause the DHCP server to spin if one-lease-per-client was enabled.
• Fix a bug that was causing core dumps on BSD/os in the presence of malformed packets.
• In partner-down state, don't restrict lease lengths to MCLT.
• On the failover secondary, record the MCLT received from the primary so that if we come up without a connection to the primary we don't wind up giving out zero-length leases.
• Fix some compilation problems on BSD/os.
• Fix a bunch of memory leaks.
• Fix a couple of bugs in the option printer.
• Fix an obscure error reporting bug in the dns update code, and also make the message clearer when a key algorithm isn't supported.
• Fix a bug in the tracing code that prevented trace runs that used tcp connections from being played back.
• Add some additional debugging capability for catching memory leaks on exit.
• Make the client release the lease correctly on shutdown.
• Add some configurability to the build system.
• Install omshell manual page in man1, not man8.
• Craig Gwydir sent in a patch that fixes a long-standing bug in the DHCP client that could cause core dumps, but that for some reason hadn't been noticed until now.

Changes since 3.0 Release Candidate 7

• Fix a bug in failover where we weren't sending updates after a transition from communications-interrupted to normal.
• Handle expired/released/reset -> free transition according to the protocol specification (this works - the other way not only wasn't conformant, but also didn't work).
• Add a control object in both client and server that allows either daemon to be shut down cleanly.
• When writing a lease, if we run out of disk space, shut down the output file and insist on writing a new one before proceeding.
• In the server, if the OMAPI listener port is occupied, keep trying to get it, rather than simply giving up and exiting.
• Support fetching variables from leases and also updating and adding variables to leases via OMAPI.
• If two failover peers have wildly different clocks, refuse to start doing failover.
• Fix a bug in the DNS update code that could cause core dumps when running on alpha processors.
• Fixed a bug in ddns updates for static lease entries, thanks to a patch from Andrey M Linkevitch.
• Add support for Darwin/MacOS X
• Install omshell (including new documentation).
• Support DNS updates in the client (this is a very obscure feature that most DHCP client users probably will not be able to use).
• Somewhat cleaner status logging in the client.
• Make OMAPI key naming syntax compatible with the way keys are actually named (key names are domain names).
• Fix a bug in the lease file writer.
• Install DHCP ISC headers in a different place than BIND 9 ISC headers, to avoid causing trouble in BIND 9 builds.
• Don't send updates for attributes on an object when the attributes haven't changed. Support deleting attributes on remote objects.
• Fix a number of bugs in omshell, and add the unset and refresh statements.
• Handle disconnects in OMAPI a little bit more intelligently (so that the caller gets ECONNRESET instead of EINVAL).
• Fix a bunch of bugs in the handling of clients that have existing leases when the try to renew their leases while failover is operating.

Changes since 3.0 Release Candidate 6

• Fix a core dump that could happen when processing a DHCPREQUEST from a client that had a host declaration that contained both a fixed-address declaration and a dhcp-client-identifier option declaration, if the client identifier was longer than nine bytes.
• Fix a memory leak that could happen in certain obscure cases when using omapi to manipulate leases.
• Fix some bugs and omissions in omshell.

Changes since 3.0 Release Candidate 5

• Fix a bug in omapi_object_dereference that prevented objects in chains from having their reference counts decreased on dereference.
• Fix a bug in omapi_object_dereference that would prevent object chains from being freed upon removal of the last reference external to the chain.
• Fix a number of other memory leaks in the OMAPI protocol subsystem.
• Add code in the OMAPI protocol handler to trace memory leakage.
• Clean up the memory allocation/reference history printer.
• Support input of dotted quads and colon-separated hex lists as attribute values in omshell.
• Fix a typo in the linux interface discovery code.
• Conditionalize a piece of trace code that wasn't conditional.

Changes since 3.0 Release Candidate 4

• Fix a bug that would prevent leases from being abandoned properly on DHCPDECLINE.
• Fix failover peer OMAPI support.
• In failover, correctly handle expiration of leases. Previously, leases would never be reclaimed because they couldn't make the transition from EXPIRED to FREE.
• Fix some broken failover state transitions.
• Documentation fixes.
• Take out an unnecessary check in DHCP relay agent information option stashing code that was preventing REBINDING clients from rebinding.
• Prevent failover peers from allocating leases in DHCPREQUEST processing if the lease belongs to the other server.
• Record server version in lease file introductory comment.
• Correctly report connection errors in OMAPI and failover.
• Make authentication signature algorithm name comparisons in OMAPI case-insensitive.
• Fix compile problem on SunOS 4.x
• If a signature algorithm is not terminated with '.', terminate it so that comparisons between fully-qualified names will work consistently.
• Different SIOCGIFCONF probe code, may "fix" problem on some Linux systems with the probe not working correctly.
• Don't allow user to type omapi key on command line of omshell.

Changes since 3.0 Release Candidate 3

• Do lease billing on startup in a way that I *think* will finally do the billing correctly - the previous method could overbill as a result of duplicate leases.
• Document OMAPI server objects.

Changes since 3.0 Release Candidate 2 Patchlevel 1

• Fix some problems in the DDNS update code. Thanks to Albert Herranz for figuring out the main problem.
• Fix some reference counting errors on host entries that were causing core dumps.
• Fix a byte-swap bug in the token ring code, thanks to Jochen Friedrich.
• Fix a bug in lease billing, thanks to Jonas Bulow.

Changes since 3.0 Release Candidate 2

• Change the conditions under which a DHCPRELEASE is actually committed to be consistent with lease binding states rather than using the lease end time. This may fix some problems with the billing class code.
• Fix a bug where lease updates would fail on Digital Unix (and maybe others) because malloc was called with a size of zero.
• Fix a core dump that happens when the DHCP server can't create its trace file.

Changes since 3.0 Release Candidate 1 Patchlevel 1

• Fix the dhcp_failover_put_message to not attempt to allocate a zero-length buffer. Some versions of malloc() fail if you try to allocate a zero-length buffer, and this was causing problems on, e.g., Digital Unix.
• Fix a case where the failover code was printing an error message when no error had occurred.
• Fix a problem where when a server went down and back up again, the peer would not see a state transition and so would stay in the non-communicating state.
• Be smart about going into recover_wait.
• Fix a problem in the failover implementation where peers would fail to come into sync if interrupted in the RECOVER state. This could have been the cause of some problems people have reported recently.
• Fix a problem with billing classes where they would not be unbilled when the client lease expired.
• If select fails, figure out which descriptor is bad, and cut it out of the I/O loop. This prevents a potentially nasty spin. I haven't heard any report it in a while, but it came up consistently in testing.
• Fix a bug in the relay agent where if you specified interfaces on the command line, it would fail.
• Fix a couple of small bugs in the omapi connection object (no known user impact).
• Add the missing 3.0 Beta 1 lease conversion script.
• Read dhcp client script hooks if they exist, rather than only if they're executable.

Changes since 3.0 Release Candidate 1

• Fix a small bug in binary-to-ascii, thanks to H. Peter Anvin of Transmeta.
• Fix a memory smash that happens when fixed-address leases are used. ANY SITE AT WHICH FIXED-ADDRESS STATEMENTS ARE BEING USED SHOULD UPGRADE IMMEDIATELY. This has been a long-standing bug - thanks to Alvise Nobile for discovering it and helping me to find it!
• There is a known problem with the DHCP server doing failover on Compaq Alpha systems. This patchlevel is not a release candidate because of this bug. The bug should be straightforward to fix, so a new release candidate is expected shortly.
• There is a known problem in the DDNS update code that is probably a bug, and is not, as far as we know, fixed in this patchlevel.

Changes since 3.0 Beta 2 Patchlevel 24

• Went over problematic failover state transitions and made them all work, so that failover should now be much less fragile.
• Add some dhcpctl and omapi documentation
• Fix compile errors when compiling with unusual predefines.
• Make Token Ring work on Linux 2.4
• Fix the Digital Unix BPF_WORDALIGN bug.
• Fix some dhcp client documentation errors.
• Update some parts of the README file.
• Support GCC on SCO.

Changes since 3.0 Beta 2 Patchlevel 23

• Fix a bug in the DNS update code where a status code was not being checked. This may have been causing core dumps.
• When parsing the lease file, if a lease declaration includes a billing class statement, and the lease already has a billing class, unbill the old class.
• When processing failover transactions, where acks will be deferred, process the state transition immediately.
• Don't try to use the new SIOCGIFCONF buffer size detection code on Linux 2.0, which doesn't provide this functionality.
• Apply a patch suggested by Tuan Uong for a problem in dlpi.c.
• Fix a problem in using the which command in the configure script.
• Fix a parse error in the client when setting up an omapi listener.
• Document the -n and -g flags to the client.
• Make sure there is always a stdin and stdout on startup. This prevents shell scripts from accidentally writing error messages into configuration files that happen to be opened as stderr.
• If an interface is removed, the client will now notice that it is gone rather than spinning. This has only been tested on NetBSD.
• The client will attempt to get an address even if it can't create a lease file.
• Don't overwrite tracefiles.
• Fix some memory allocation bugs in failover.

Changes since 3.0 Beta 2 Patchlevel 22

• Apply some patches suggested by Cyrille Lefevre, who is maintaining the FreeBSD ISC DHCP Distribution port.
• Fix a core dump in DHCPRELEASE.

Changes since 3.0 Beta 2 Patchlevel 21

• This time for sure: fix the spin described in the changes for pl20.

Changes since 3.0 Beta 2 Patchlevel 20

• Fix a problem with Linux detecting large numbers of interfaces (Ben)
• Fix a memory smash in the quotify code, which was introduced in pl19.
• Actually fix the spin described in the changes for pl20. The previous fix only partially fixed the problem - enough to get it past the regression test.

Changes since 3.0 Beta 2 Patchlevel 19

• Fix a bug that could cause the server to abort if compiled with POINTER_DEBUG enabled.
• Fix a bug that could cause the server to spin when responding to a DHCPREQUEST.
• Apply Joost Mulders' suggested patches for DLPI on x86.
• Support NUL characters in quoted strings.
• Install unformatted man pages on SunOS.

Changes since 3.0 Beta 2 Patchlevel 18

• Allow the server to be placed in partner-down state using OMAPI. (Damien Neil)
• Implement omshell, which can be used to do arbitrary things to the server (in theory). (Damien Neil)
• Fix a case where if a client had two different leases the server could actually dereference the second one when it hadn't been referenced, leading to memory corruption and a core dump. (James Brister)
• Fix a case where a client could request the address of another client's lease, but find_lease wouldn't detect that the other client had it, and would attempt to allocate it to the client, resulting in a lease conflict message.
• Fix a case where a client with more than one client identifier could be given a lease where the hardware address was correct but the client identifier was not, resulting in a lease conflict message.
• Fix a problem where the server could write out a colon-separated hex list as a value for a variable, which would then not parse. The fix is to always write strings as quoted strings, with any non-printable characters quoted as octal escape sequences. So a file written the old way still won't work, but new files written this way will work.
• Fix documentation for sending non-standard options.
• Use unparsable names for unknown options. WARNING: this will break any configuration files that use the option-nnn convention. If you want to continue to use this convention for some options, please be sure to write a definition, like this:
  

  option option-nnn code nnn = string;

  You can use a descriptive name instead of option-nnn if you like.
• Fix a problem where we would see a DHCPDISCOVER/DHCPOFFER/ DHCPREQUEST/DHCPACK/DHCPREQUEST/DHCPNAK sequence. This was the result of a deceptively silly bug in supersede_lease.
• Fix client script exit status check, according to a fix supplied by Hermann Lauer.
• Fix an endianness bug in the tracefile support, regarding ICMP messages.
• Fix a bug in the client where the medium would not work correctly if it contained quoted strings.

** there was no pl17 **

Changes since 3.0 Beta 2 Patchlevel 16

• Add support for transaction tracing. This allows the state of the DHCP server on startup, and all the subsequent transactions, to be recorded in a file which can then be played back to reproduce the behaviour of the DHCP server. This can be used to quickly reproduce bugs that cause core dumps or corruption, and also for tracking down memory leaks.
• Incorporate some bug fixes provided by Joost Mulders for the DLPI package which should clear up problems people have been seeing on Solaris.
• Fix bugs in the handling of options stored as linked lists (agent options, fqdn options and nwip options) that could cause memory corruption and core dumps.
• Fix a bug in DHCPREQUEST handling that resulted in DHCPNAK messages not being send in some cases when they were needed.
• Make the lease structure somewhat more compact.
• Make initial failover startup *much* faster. This was researched and implemented by Damien Neil.
• Add a --version flag to all executables, which prints the program name and version to standard output.
• Don't rewrite the lease file every thousand leases.
• A bug in nit.c for older SunOS machines was fixed by a patch sent in by Takeshi Hagiwara.
• Fix a memory corruption bug in the DHCP client.
• Lots of documentation updates.
• Add a feature allowing environment variables to be passed to the DHCP client script on the DHCP client command line.
• Fix client medium support, which had been broken for some time.
• Fix a bug in the DHCP client initial startup backoff interval, which would cause two DHCPDISCOVERS to be sent back-to-back on startup.

Changes since 3.0 Beta 2 Patchlevel 15

• Some documentation tweaks.
• Maybe fix a problem in the DLPI code.
• Fix some error code space inconsistencies in ddns update code.
• Support relay agents that intercept unicast DHCP messages to stuff agent options into them.
• Fix a small memory leak in the relay agent option support code.
• Fix a core dump that would occur if a packet was sent with no options.

Changes since 3.0 Beta 2 Patchlevel 14

• Finish fixing a long-standing bug in the agent options code. This was causing core dumps and failing to operate correctly - in particular, agent option stashing wasn't working. Agent option stashing should now be working, meaning that agent options can be used in class statements to control address allocation.
• Fix up documentation.
• Fix a couple of small memory leaks that would have added up significantly in a high-demand situation.
• Add a log-facility configuration parameter.
• Fix a compile error on some older operating systems.
• Add the ability in the client to execute certain statements before transmitting packets to the server. Handy for debugging; not much practical use otherwise.
• Don't send faked-out giaddr when renewing or bound - again, useful for debugging.

Changes since 3.0 Beta 2 Patchlevel 13

• Fixed a problem where the fqdn decoder would sometimes try to store an option with an (unsigned) negative length, resulting in a core dump on some systems.
• Work around the Win98 DHCP client, which NUL-terminates the FQDN option.
• Work around Win98 and Win2k clients that will claim they want to do the update even when they don't have any way to do it.
• Fix some log messages that can be printed when failover is operating that were not printing enough information.
• It was possible for a DHCPDISCOVER to get an allocation even when the state machine said the server shouldn't be responding.
• Don't load balance DHCPREQUESTs from clients in RENEWING and REBINDING, since in RENEWING, if we heard it, it's for us, and in REBINDING, the client wouldn't have got to REBINDING if its primary were answering.
• When we get a bogus state lease binding state transition, don't do the transition.

Changes since 3.0 Beta 2 Patchlevel 12

• Fixed a couple of silly compile errors.

Changes since 3.0 Beta 2 Patchlevel 11

• Albert Herranz tracked down and fixed a subtle bug in the base64 decoder that would prevent any key with an 'x' in its base64 representation from working correctly.
• Thanks to Chris Cheney and Michael Sanders, we have a fix for the hang that they both spotted in the DHCP server - when one-lease-per-client was set, the code to release the "other" lease could spin.
• Fix a problem with alignment of the input buffer in bpf in cases where two packets arrive in the same bpf read.
• Fix a problem where the relay agent would crash if you specified an interface name on the command line.
• Add the ability to conditionalize client behaviour based on the client state.
• Add support for the FQDN option, and added support for a new way of doing ddns updates (ddns update style interim) that allows more than one DHCP server to update the DNS for the same network(s). This was implemented by Damien Neil with some additional functionality added by Ted Lemon.
• Damien added a "log" statement, so that the configuration file can be made to log debugging information and other information.
• Fixed a bug that caused option buffers not to be terminated with an end option.
• Fixed a long-standing bug in the support for option spaces where the options are stored as an ordered list rather than in a hash table, which could theoretically result in memory pool corruption.
• Prevent hardware declarations with no actual hardware address from being written as something unparsable, and behave correctly in the face of a null hardware address on input.
• Allow key names to be FQDNs, and qualify the algorithm name if it is specified unqualified.
• Modify the DDNS update code so that it never prints the "resolver failed" message, but instead says *why* the resolver failed.
• Officially support the subnet selection option, which now has an RFC.
• Fix a build bug on MacOS X.
• Allow administrator to disable ping checking.
• Clean up dhcpd.conf documentation and add more information about how it works.

Changes since 3.0 Beta 2 Patchlevel 10

• Fix a bug introduced during debugging (!) and accidentally committed to CVS.

Changes since 3.0 Beta 2 Patchlevel 9

• Fix DHCP client handling of vendor encapsulated options.
• Fix a bug in the handling of relay agent information options introduced in patchlevel 9.
• Stash agent options on client leases by default, and use the stashed options at renewal time.
• Add the ability to test the client's binding state in the client configuration language.
• Fix a core dump in the DNS update code.
• Fix some expression evaluation bugs that were causing updates to be done when no client hostname was received.
• Fix expression evaluation debugging printfs.
• Teach pretty_print_option to print options in option spaces other than the DHCP option space.
• Add a warning message if the RHS of a not is not boolean.
• Never select for more than a day, because some implementations of select will just fail if the timeout is too long (!).
• Fix a case where a DHCPDISCOVER from an unknown network would be silently dropped.
• Fix a bug where if a client requested an IP address for which a different client had the lease, the DHCP server would reallocate it anyway.
• Fix the DNS update code so that if the client changes its name, the DNS will be correctly updated.

Changes since 3.0 Beta 2 Patchlevel 8

• Oops, there was another subtle math error in the header-length bounds-checking.

Changes since 3.0 Beta 2 Patchlevel 7

• Oops, forgot to byte-swap udp header length before bounds-checking it.

Changes since 3.0 Beta 2 Patchlevel 6

• Fix a possible DoS attack where a client could cause the checksummer to dump core. This was a read, not a write, so it shouldn't be possible to exploit it any further than that.
• Implement client- and server-side support for using the Client FQDN option.
• Support for other option spaces in the client has been added. This means that it is now possible to define a vendor option space on the client, request options in that space from the server (which must define the same option space), and then use those options in the client. This also allows NWIP and Client FQDN options to be used meaningfully.
• Add object initializer support. This means that objects can now be initialized to something other than all-zeros when allocated, which makes, e.g., the interface object support code a little more robust.
• Fix an off-by-one bug in the host stuffer. This was causing host deletes not the work, and may also have been causing OMAPI connections to get dropped. Thanks to James Brister for tracking this one down!
• Fixed a core dump in the interface discovery code that is triggered when there is no subnet declaration for an interface, but the server decides to continue running. Thanks to Shane Kerr for tracking down and fixing this problem.

Changes since 3.0 Beta 2 Patchlevel 5

• Fix a bug in the recent enhancement to the interface discovery code to support arbitrary-length interface lists.
• Support NUL-terminated DHCP options when initializing client-script environment.
• Fix suffix operator.
• Fix NetWare/IP option parsing.
• Better error/status checking in dhcpctl initialization and omapi connection code.
• Fix a potential memory smash in dhcpctl code.
• Fix SunOS4 and (maybe) Ultrix builds.
• Fix a bug where a certain sort of incoming packet could cause a core dump on Solaris (and probably elsewhere).
• Add some more safety checks in error logging code.
• Add support for ISC_R_INCOMPLETE in OMAPI protocol connection code.
• Fix relay agent so that if an interface is specified on the command line, the relay agent does not dump core.
• Fix class matching so that match if can be combined with match or spawn with.
• Do not allow spurious leases in the lease database to introduce potentially bogus leases into the in-memory database.
• Fix a byte-order problem in the client hardware address type code for OMAPI.
• Be slightly less picky about what sort of hardware addresses OMAPI can install in host declarations.

Changes since 3.0 Beta 2 Patchlevel 4

• Incorporated Peter Marschall's proposed change to array/record parsing, which allows things like the slp-agent option to be encoded correctly. Thanks very much to Peter for taking the initiative to do this, and for doing such a careful job of it (e.g., updating the comments)!
• Added an encoding for the slp-agent option. :')
• Fixed SunOS 4 build. Thanks to Robert Elz for responding to my request for help on this with patches!
• Incorporated a change that should fix a problem reported by Philippe Jumelle where when the network connection between two servers is lost, they never reconnect.
• Fix client script files other than that for NetBSD to actually use make_resolv_conf as documented in the manual page.
• Fix a bug in the packet handling code that could result in a core dump.
• Fix a bug in the bootp code where responses on the local net would be sent to the wrong MAC address. Thanks to Jerry Schave for catching this one.

Changes since 3.0 Beta 2 Patchlevel 3

• In the DHCP client, execute client statements prior to using the values of options, so that the client configuration can override, e.g., the lease renewal time.
• Fix a reference counting error that would result in very reproducible failures in updates, as well as occasional core dumps, if a zone was declared without a key.
• Fix some Linux 2.0 compilation problems.
• Fix a bug in scope evaluation during execution of "on" statements that caused values not to be recorded on leases.
• If the dhcp-max-message-size option is specified in scope, and the client didn't send this option, use the one specified in scope to determine the maximum size of the response.

Changes since 3.0 Beta 2 Patchlevel 2

• Fix a case where spawning subclasses were being allocated incorrectly, resulting in a core dump.
• Fix a case where the DHCP server might inappropriately NAK a RENEWING client.
• Fix a place dhcprequest() where static leases could leak.
• Include memory.h in omapip_p.h so that we don't get warnings about using memcmp().

Changes since 3.0 Beta 2 Patchlevel 1

• Notice when SIOCFIGCONF returns more data than fit in the buffer - allocate a larger buffer, and retry. Thanks to Greg Fausak for pointing this out.
• In the server, if no interfaces were configured, report an error and exit.
• Don't ever record a state of 'startup'.
• Don't try to evaluate the local failover binding address if none was specified. Thanks to Joseph Breu for finding this.