Release Notes¶
Contents
Introduction¶
BIND 9.16 (Extended Support Version) is a stable branch of BIND. This document summarizes significant changes since the last production release on that branch. Please see the CHANGES file for a more detailed list of changes and bug fixes.
Note on Version Numbering¶
As of BIND 9.13/9.14, BIND has adopted the “odd-unstable/even-stable” release numbering convention. BIND 9.16 contains new features that were added during the BIND 9.15 development process. Henceforth, the 9.16 branch will be limited to bug fixes, and new feature development will proceed in the unstable 9.17 branch.
Supported Platforms¶
To build on Unix-like systems, BIND requires support for POSIX.1c threads (IEEE Std 1003.1c-1995), the Advanced Sockets API for IPv6 (RFC 3542), and standard atomic operations provided by the C compiler.
The libuv asynchronous I/O library and the OpenSSL cryptography library must be available for the target platform. A PKCS#11 provider can be used instead of OpenSSL for Public Key cryptography (i.e., DNSSEC signing and validation), but OpenSSL is still required for general cryptography operations such as hashing and random number generation.
More information can be found in the PLATFORMS.md
file that is
included in the source distribution of BIND 9. If your compiler and
system libraries provide the above features, BIND 9 should compile and
run. If that is not the case, the BIND development team will generally
accept patches that add support for systems that are still supported by
their respective vendors.
Download¶
The latest versions of BIND 9 software can always be found at https://www.isc.org/download/. There you will find additional information about each release, source code, and pre-compiled versions for Microsoft Windows operating systems.
Notes for BIND 9.16.23¶
Bug Fixes¶
Reloading a catalog zone which referenced a missing/deleted member zone triggered a runtime check failure, causing
named
to exit prematurely. This has been fixed. [GL #2308]
Notes for BIND 9.16.22¶
Security Fixes¶
The
lame-ttl
option controls how longnamed
caches certain types of broken responses from authoritative servers (see the security advisory for details). This caching mechanism could be abused by an attacker to significantly degrade resolver performance. The vulnerability has been mitigated by changing the default value oflame-ttl
to0
and overriding any explicitly set value with0
, effectively disabling this mechanism altogether. ISC’s testing has determined that doing that has a negligible impact on resolver performance while also preventing abuse. Administrators may observe more traffic towards servers issuing certain types of broken responses than in previous BIND 9 releases, depending on client query patterns. (CVE-2021-25219)ISC would like to thank Kishore Kumar Kothapalli of Infoblox for bringing this vulnerability to our attention. [GL #2899]
Feature Changes¶
The use of native PKCS#11 for Public-Key Cryptography in BIND 9 has been deprecated in favor of the engine_pkcs11 OpenSSL engine from the OpenSC project. The
--with-native-pkcs11
configuration option will be removed in the next major BIND 9 release. The option to use the engine_pkcs11 OpenSSL engine is already available in BIND 9; please see the ARM section on PKCS#11 for details. [GL #2691]Old-style Dynamically Loadable Zones (DLZ) drivers that had to be enabled in
named
at build time have been marked as deprecated in favor of new-style DLZ modules. Old-style DLZ drivers will be removed in the next major BIND 9 release. [GL #2814]The
map
zone file format has been marked as deprecated and will be removed in the next major BIND 9 release. [GL #2882]named
andnamed-checkconf
now exit with an error when a single port configured forquery-source
,transfer-source
,notify-source
,parental-source
, and/or their respective IPv6 counterparts clashes with a global listening port. This configuration has not been supported since BIND 9.16.0, but no error was reported until now (even though sending UDP messages such as NOTIFY failed). [GL #2888]named
andnamed-checkconf
now issue a warning when there is a single port configured forquery-source
,transfer-source
,notify-source
,parental-source
, and/or for their respective IPv6 counterparts. [GL #2888]
Bug Fixes¶
A recent change introduced in BIND 9.16.21 inadvertently broke backward compatibility for the
check-names master ...
andcheck-names slave ...
options, causing them to be silently ignored. This has been fixed and these options now work properly again. [GL #2911]When new IP addresses were set up by the operating system during
named
startup, it could fail to listen for TCP connections on the newly added interfaces. [GL #2852]
Notes for BIND 9.16.21¶
New Features¶
Support for HTTPS and SVCB record types has been added. (This does not include ADDITIONAL section processing for these record types, only basic support for RR type parsing and printing.) [GL #1132]
Feature Changes¶
When
dnssec-signzone
signs a zone using a successor key whose predecessor is still published, it now only refreshes signatures for RRsets which have an invalid signature, an expired signature, or a signature which expires within the provided cycle interval. This allowsdnssec-signzone
to gradually replace signatures in a zone whose ZSK is being rolled over (similarly to whatauto-dnssec maintain;
does). [GL #1551]
Bug Fixes¶
A recent change to the internal memory structure of zone databases inadvertently neglected to update the MAPAPI value for zone files in
map
format. This caused version 9.16.20 ofnamed
to attempt to load files into memory that were no longer compatible, triggering an assertion failure on startup. The MAPAPI value has now been updated, sonamed
rejects outdated files when encountering them. [GL #2872]Zone files in
map
format whose size exceeded 2 GB failed to load. This has been fixed. [GL #2878]named
was unable to run as a Windows Service under certain circumstances. This has been fixed. [GL #2837]Stale data in the cache could cause
named
to send non-minimized queries despite QNAME minimization being enabled. This has been fixed. [GL #2665]When a DNSSEC-signed zone which only has a single signing key available is migrated to
dnssec-policy
, that key is now treated as a Combined Signing Key (CSK). [GL #2857]When a dynamic zone was made available in another view using the
in-view
statement, runningrndc freeze
always reported analready frozen
error even though the zone was successfully frozen. This has been fixed. [GL #2844]
Notes for BIND 9.16.20¶
Security Fixes¶
Fixed an assertion failure that occurred in
named
when it attempted to send a UDP packet that exceeded the MTU size, if Response Rate Limiting (RRL) was enabled. (CVE-2021-25218) [GL #2856]named
failed to check the opcode of responses when performing zone refreshes, stub zone updates, and UPDATE forwarding. This could lead to an assertion failure under certain conditions and has been addressed by rejecting responses whose opcode does not match the expected value. [GL #2762]
Feature Changes¶
Testing revealed that setting the thread affinity for various types of
named
threads led to inconsistent recursive performance, as sometimes multiple sets of threads competed over a single resource.Due to the above,
named
no longer sets thread affinity. This causes a slight dip of around 5% in authoritative performance, but recursive performance is now consistently improved. [GL #2822]CDS and CDNSKEY records can now be published in a zone without the requirement that they exactly match an existing DNSKEY record, as long as the zone is signed with an algorithm represented in the CDS or CDNSKEY record. This allows a clean rollover from one DNS provider to another when using a multiple-signer DNSSEC configuration. [GL #2710]
Bug Fixes¶
Authentication of
rndc
messages could fail if acontrols
statement was configured with multiple key algorithms for the same listener. This has been fixed. [GL #2756]
Notes for BIND 9.16.19¶
New Features¶
Using a new configuration option,
parental-agents
, each zone can now be associated with a list of servers that can be used to check the DS RRset in the parent zone. This enables automatic KSK rollovers. [GL #1126]
Feature Changes¶
IP fragmentation has been disabled for outgoing UDP sockets. Errors triggered by sending DNS messages larger than the specified path MTU are properly handled by sending empty DNS replies with the
TC
(TrunCated) bit set, which forces DNS clients to fall back to TCP. [GL #2790]
Bug Fixes¶
The code managing RFC 5011 trust anchors created an invalid placeholder keydata record upon a refresh failure, which prevented the database of managed keys from subsequently being read back. This has been fixed. [GL #2686]
Signed, insecure delegation responses prepared by
named
either lacked the necessary NSEC records or contained duplicate NSEC records when both wildcard expansion and CNAME chaining were required to prepare the response. This has been fixed. [GL #2759]If
nsupdate
sends an SOA request and receives a REFUSED response, it now fails over to the next available server. [GL #2758]A bug that caused the NSEC3 salt to be changed on every restart for zones using KASP has been fixed. [GL #2725]
The configuration-checking code failed to account for the inheritance rules of the
dnssec-policy
option. This has been fixed. [GL #2780]The fix for [GL #1875] inadvertently introduced a deadlock: when locking key files for reading and writing, the
in-view
logic was not considered. This has been fixed. [GL #2783]A race condition could occur where two threads were competing for the same set of key file locks, leading to a deadlock. This has been fixed. [GL #2786]
Notes for BIND 9.16.18¶
Bug Fixes¶
When preparing DNS responses,
named
could replace the lettersW
(uppercase) andw
(lowercase) with\000
. This has been fixed. [GL #2779]The configuration-checking code failed to account for the inheritance rules of the
key-directory
option. As a side effect of this flaw, the code detectingkey-directory
conflicts for zones using KASP incorrectly reported unique key directories as being reused. This has been fixed. [GL #2778]
Notes for BIND 9.16.17¶
Feature Changes¶
After the network manager was introduced to
named
to handle incoming traffic, it was discovered that recursive performance had degraded compared to previous BIND 9 versions. This has now been fixed by processing internal tasks inside network manager worker threads, preventing resource contention among two sets of threads. [GL #2638]Zone dumping tasks are now run on separate asynchronous thread pools. This change prevents zone dumping from blocking network I/O. [GL #2732]
inline-signing
was incorrectly described as being inherited from theoptions
/view
levels and was incorrectly accepted at those levels without effect. This has been fixed;named.conf
files withinline-signing
at those levels no longer load. [GL #2536]
Bug Fixes¶
The calculation of the estimated IXFR transaction size in
dns_journal_iter_init()
was invalid. This resulted in excessive AXFR-style IXFR responses. [GL #2685]Fixed an assertion failure that could occur if stale data was used to answer a query, and then a prefetch was triggered after the query was restarted (for example, to follow a CNAME). [GL #2733]
If a query was answered with stale data on a server with DNS64 enabled, an assertion could occur if a non-stale answer arrived afterward. This has been fixed. [GL #2731]
Fixed an error which caused the
IP_DONTFRAG
socket option to be enabled instead of disabled, leading to errors when sending oversized UDP packets. [GL #2746]Zones which are configured in multiple views, with different values set for
dnssec-policy
and with identical values set forkey-directory
, are now detected and treated as a configuration error. [GL #2463]A race condition could occur when reading and writing key files for zones using KASP and configured in multiple views. This has been fixed. [GL #1875]
Notes for BIND 9.16.16¶
Feature Changes¶
DNSSEC responses containing NSEC3 records with iteration counts greater than 150 are now treated as insecure. [GL #2445]
The maximum supported number of NSEC3 iterations that can be configured for a zone has been reduced to 150. [GL #2642]
The default value of the
max-ixfr-ratio
option was changed tounlimited
, for better backwards compatibility in the stable release series. [GL #2671]Zones that want to transition from secure to insecure mode without becoming bogus in the process must now have their
dnssec-policy
changed first toinsecure
, rather thannone
. After the DNSSEC records have been removed from the zone, thednssec-policy
can be set tonone
or removed from the configuration. Setting thednssec-policy
toinsecure
causes CDS and CDNSKEY DELETE records to be published. [GL #2645]The implementation of the ZONEMD RR type has been updated to match RFC 8976. [GL #2658]
The
draft-vandijk-dnsop-nsec-ttl
IETF draft was implemented: NSEC(3) TTL values are now set to the minimum of the SOA MINIMUM value or the SOA TTL. [GL #2347]
Bug Fixes¶
It was possible for corrupt journal files generated by an earlier version of
named
to cause problems after an upgrade. This has been fixed. [GL #2670]TTL values in cache dumps were reported incorrectly when
stale-cache-enable
was set toyes
. This has been fixed. [GL #389] [GL #2289]A deadlock could occur when multiple
rndc addzone
,rndc delzone
, and/orrndc modzone
commands were invoked simultaneously for different zones. This has been fixed. [GL #2626]named
andnamed-checkconf
did not report an error when multiple zones with thednssec-policy
option set were using the same zone file. This has been fixed. [GL #2603]If
dnssec-policy
was active and a private key file was temporarily offline during a rekey event,named
could incorrectly introduce replacement keys and break a signed zone. This has been fixed. [GL #2596]When generating zone signing keys, KASP now also checks for key ID conflicts among newly created keys, rather than just between new and existing ones. [GL #2628]
Notes for BIND 9.16.15¶
Security Fixes¶
A malformed incoming IXFR transfer could trigger an assertion failure in
named
, causing it to quit abnormally. (CVE-2021-25214)ISC would like to thank Greg Kuechle of SaskTel for bringing this vulnerability to our attention. [GL #2467]
named
crashed when a DNAME record placed in the ANSWER section during DNAME chasing turned out to be the final answer to a client query. (CVE-2021-25215)ISC would like to thank Siva Kakarla for bringing this vulnerability to our attention. [GL #2540]
When a server’s configuration set the
tkey-gssapi-keytab
ortkey-gssapi-credential
option, a specially crafted GSS-TSIG query could cause a buffer overflow in the ISC implementation of SPNEGO (a protocol enabling negotiation of the security mechanism used for GSSAPI authentication). This flaw could be exploited to crashnamed
binaries compiled for 64-bit platforms, and could enable remote code execution whennamed
was compiled for 32-bit platforms. (CVE-2021-25216)This vulnerability was reported to us as ZDI-CAN-13347 by Trend Micro Zero Day Initiative. [GL #2604]
Feature Changes¶
The ISC implementation of SPNEGO was removed from BIND 9 source code. Instead, BIND 9 now always uses the SPNEGO implementation provided by the system GSSAPI library when it is built with GSSAPI support. All major contemporary Kerberos/GSSAPI libraries contain an implementation of the SPNEGO mechanism. [GL #2607]
The default value for the
stale-answer-client-timeout
option was changed from1800
(ms) tooff
. The default value may be changed again in future releases as this feature matures. [GL #2608]
Bug Fixes¶
TCP idle and initial timeouts were being incorrectly applied: only the
tcp-initial-timeout
was applied on the whole connection, even if the connection were still active, which could prevent a large zone transfer from being sent back to the client. The default setting fortcp-initial-timeout
was 30 seconds, which meant that any TCP connection taking more than 30 seconds was abruptly terminated. This has been fixed. [GL #2583]When
stale-answer-client-timeout
was set to a positive value and recursion for a client query completed whennamed
was about to look for a stale answer, an assertion could fail inquery_respond()
, resulting in a crash. This has been fixed. [GL #2594]If zone journal files written by BIND 9.16.11 or earlier were present when BIND was upgraded to BIND 9.16.13 or BIND 9.16.14, the zone file for that zone could have been inadvertently rewritten with the current zone contents. This caused the original zone file structure (e.g. comments,
$INCLUDE
directives) to be lost, although the zone data itself was preserved. [GL #2623]After upgrading to BIND 9.16.13, journal files for trust anchor databases (e.g.
managed-keys.bind.jnl
) could be left in a corrupt state. (Other zone journal files were not affected.) This has been fixed. If a corrupt journal file is detected,named
can now recover from it. [GL #2600]When sending queries over TCP,
dig
now properly handles+tries=1 +retry=0
by not retrying the connection when the remote server closes the connection prematurely. [GL #2490]CDS/CDNSKEY DELETE records are now removed when a zone transitions from a secure to an insecure state.
named-checkzone
also no longer reports an error when such records are found in an unsigned zone. [GL #2517]Zones using KASP could not be thawed after they were frozen using
rndc freeze
. This has been fixed. [GL #2523]After
rndc checkds -checkds
orrndc dnssec -rollover
is used,named
now immediately attempts to reconfigure zone keys. This change prevents unnecessary key rollover delays. [GL #2488]Previously, a memory leak could occur when
named
failed to bind a UDP socket to a network interface. This has been fixed. [GL #2575]
Notes for BIND 9.16.14¶
Note
The BIND 9.16.14 release was withdrawn after a backporting bug was discovered during pre-release testing. ISC would like to acknowledge the assistance of Natan Segal of Bluecat Networks.
Notes for BIND 9.16.13¶
New Features¶
A new
purge-keys
option has been added todnssec-policy
. It sets the period of time that key files are retained after becoming obsolete due to a key rollover; the default is 90 days. This feature can be disabled by settingpurge-keys
to 0. [GL #2408]
Feature Changes¶
When serve-stale is enabled and stale data is available,
named
now returns stale answers upon encountering any unexpected error in the query resolution process. This may happen, for example, if thefetches-per-server
orfetches-per-zone
limits are reached. In this case,named
attempts to answer DNS requests with stale data, but does not start thestale-refresh-time
window. [GL #2434]
Bug Fixes¶
Zone journal (
.jnl
) files created by versions ofnamed
prior to 9.16.12 were no longer compatible; this could cause problems when upgrading if journal files were not synchronized first. This has been corrected: older journal files can now be read when starting up. When an old-style journal file is detected, it is updated to the new format immediately after loading.Note that journals created by the current version of
named
are not usable by versions prior to 9.16.12. Before downgrading to a prior release, users are advised to ensure that all dynamic zones have been synchronized usingrndc sync -clean
.A journal file’s format can be changed manually by running
named-journalprint -d
(downgrade) ornamed-journalprint -u
(upgrade). Note that this must not be done whilenamed
is running. [GL #2505]named
crashed when it was allowed to serve stale answers andstale-answer-client-timeout
was triggered without any (stale) data available in the cache to answer the query. [GL #2503]If an outgoing packet exceeded
max-udp-size
,named
dropped it instead of sending back a proper response. To prevent this problem, theIP_DONTFRAG
option is no longer set on UDP sockets, which has been happening since BIND 9.16.11. [GL #2466]NSEC3 records were not immediately created when signing a dynamic zone using
dnssec-policy
withnsec3param
. This has been fixed. [GL #2498]A memory leak occurred when
named
was reconfigured after adding an inline-signed zone withauto-dnssec maintain
enabled. This has been fixed. [GL #2041]An invalid direction field (not one of
N
,S
,E
,W
) in a LOC record resulted in an INSIST failure when a zone file containing such a record was loaded. [GL #2499]
Notes for BIND 9.16.12¶
Security Fixes¶
When
tkey-gssapi-keytab
ortkey-gssapi-credential
was configured, a specially crafted GSS-TSIG query could cause a buffer overflow in the ISC implementation of SPNEGO (a protocol enabling negotiation of the security mechanism to use for GSSAPI authentication). This flaw could be exploited to crashnamed
. Theoretically, it also enabled remote code execution, but achieving the latter is very difficult in real-world conditions. (CVE-2020-8625)This vulnerability was responsibly reported to us as ZDI-CAN-12302 by Trend Micro Zero Day Initiative. [GL #2354]
New Features¶
When a secondary server receives a large incremental zone transfer (IXFR), it can have a negative impact on query performance while the incremental changes are applied to the zone. To address this,
named
can now limit the size of IXFR responses it sends in response to zone transfer requests. If an IXFR response would be larger than an AXFR of the entire zone, it will send an AXFR response instead.This behavior is controlled by the
max-ixfr-ratio
option - a percentage value representing the ratio of IXFR size to the size of a full zone transfer. The default is100%
. [GL #1515]A new option,
stale-answer-client-timeout
, has been added to improvenamed
’s behavior with respect to serving stale data. The option defines the amount of timenamed
waits before attempting to answer the query with a stale RRset from cache. If a stale answer is found,named
continues the ongoing fetches, attempting to refresh the RRset in cache until theresolver-query-timeout
interval is reached.The default value is
1800
(in milliseconds) and the maximum value is limited toresolver-query-timeout
minus one second. A value of0
causes any available cached RRset to immediately be returned while still triggering a refresh of the data in cache.This new behavior can be disabled by setting
stale-answer-client-timeout
tooff
ordisabled
. The new option has no effect ifstale-answer-enable
is disabled. [GL #2247]
Feature Changes¶
As part of an ongoing effort to use RFC 8499 terminology,
primaries
can now be used as a synonym formasters
innamed.conf
. Similarly,notify primary-only
can now be used as a synonym fornotify master-only
. The output ofrndc zonestatus
now usesprimary
andsecondary
terminology. [GL #1948]The default value of
max-stale-ttl
has been changed from 12 hours to 1 day and the default value ofstale-answer-ttl
has been changed from 1 second to 30 seconds, following RFC 8767 recommendations. [GL #2248]The SONAMEs for BIND 9 libraries now include the current BIND 9 version number, in an effort to tightly couple internal libraries with a specific release. This change makes the BIND 9 release process both simpler and more consistent while also unequivocally preventing BIND 9 binaries from silently loading wrong versions of shared libraries (or multiple versions of the same shared library) at startup. [GL #2387]
When
check-names
is in effect, A records below an_spf
,_spf_rate
, or_spf_verify
label (which are employed by theexists
SPF mechanism defined in RFC 7208 section 5.7/appendix D.1) are no longer reported as warnings/errors. [GL #2377]
Bug Fixes¶
named
failed to start when its configuration included a zone with a non-builtinallow-update
ACL attached. [GL #2413]Previously,
dnssec-keyfromlabel
crashed when operating on an ECDSA key. This has been fixed. [GL #2178]KASP incorrectly set signature validity to the value of the DNSKEY signature validity. This has been fixed. [GL #2383]
When migrating to KASP, BIND 9 considered keys with the
Inactive
and/orDelete
timing metadata to be possible active keys. This has been fixed. [GL #2406]Fix the “three is a crowd” key rollover bug in KASP. When keys rolled faster than the time required to finish the rollover procedure, the successor relation equation failed because it assumed only two keys were taking part in a rollover. This could lead to premature removal of predecessor keys. BIND 9 now implements a recursive successor relation, as described in the paper “Flexible and Robust Key Rollover” (Equation (2)). [GL #2375]
Performance of the DNSSEC verification code (used by
dnssec-signzone
,dnssec-verify
, and mirror zones) has been improved. [GL #2073]
Notes for BIND 9.16.11¶
Feature Changes¶
The new networking code introduced in BIND 9.16 (netmgr) was overhauled in order to make it more stable, testable, and maintainable. [GL #2321]
Earlier releases of BIND versions 9.16 and newer required the operating system to support load-balanced sockets in order for
named
to be able to achieve high performance (by distributing incoming queries among multiple threads). However, the only operating systems currently known to support load-balanced sockets are Linux and FreeBSD 12, which means both UDP and TCP performance were limited to a single thread on other systems. As of BIND 9.16.11,named
attempts to distribute incoming queries among multiple threads on systems which lack support for load-balanced sockets (except Windows). [GL #2137]It is now possible to transition a zone from secure to insecure mode without making it bogus in the process; changing to
dnssec-policy none;
also causes CDS and CDNSKEY DELETE records to be published, to signal that the entire DS RRset at the parent must be removed, as described in RFC 8078. [GL #1750]When using the
unixtime
ordate
method to update the SOA serial number,named
anddnssec-signzone
silently fell back to theincrement
method to prevent the new serial number from being smaller than the old serial number (using serial number arithmetics).dnssec-signzone
now prints a warning message, andnamed
logs a warning, when such a fallback happens. [GL #2058]
Bug Fixes¶
Multiple threads could attempt to destroy a single RBTDB instance at the same time, resulting in an unpredictable but low-probability assertion failure in
free_rbtdb()
. This has been fixed. [GL #2317]named
no longer attempts to assign threads to CPUs outside the CPU affinity set. Thanks to Ole Bjørn Hessen. [GL #2245]When reconfiguring
named
, removingauto-dnssec
did not turn off DNSSEC maintenance. This has been fixed. [GL #2341]The report of intermittent BIND assertion failures triggered in
lib/dns/resolver.c:dns_name_issubdomain()
has now been closed without further action. Our initial response to this was to add diagnostic logging instead of terminatingnamed
, anticipating that we would receive further useful troubleshooting input. This workaround first appeared in BIND releases 9.17.5 and 9.16.7. However, since those releases were published, there have been no new reports of assertion failures matching this issue, but also no further diagnostic input, so we have closed the issue. [GL #2091]
Notes for BIND 9.16.10¶
New Features¶
NSEC3 support was added to KASP. A new option for
dnssec-policy
,nsec3param
, can be used to set the desired NSEC3 parameters. NSEC3 salt collisions are automatically prevented during resalting. [GL #1620]
Feature Changes¶
The default value of
max-recursion-queries
was increased from 75 to 100. Since the queries sent towards root and TLD servers are now included in the count (as a result of the fix for CVE-2020-8616),max-recursion-queries
has a higher chance of being exceeded by non-attack queries, which is the main reason for increasing its default value. [GL #2305]The default value of
nocookie-udp-size
was restored back to 4096 bytes. Sincemax-udp-size
is the upper bound fornocookie-udp-size
, this change relieves the operator from having to changenocookie-udp-size
together withmax-udp-size
in order to increase the default EDNS buffer size limit.nocookie-udp-size
can still be set to a value lower thanmax-udp-size
, if desired. [GL #2250]
Bug Fixes¶
Handling of missing DNS COOKIE responses over UDP was tightened by falling back to TCP. [GL #2275]
The CNAME synthesized from a DNAME was incorrectly followed when the QTYPE was CNAME or ANY. [GL #2280]
Building with native PKCS#11 support for AEP Keyper has been broken since BIND 9.16.6. This has been fixed. [GL #2315]
Notes for BIND 9.16.9¶
New Features¶
A new configuration option,
stale-refresh-time
, has been introduced. It allows a stale RRset to be served directly from cache for a period of time after a failed lookup, before a new attempt to refresh it is made. [GL #2066]
Bug Fixes¶
named
could crash with an assertion failure if a TCP connection were closed while a request was still being processed. [GL #2227]named
acting as a resolver could incorrectly treat signed zones with no DS record at the parent as bogus. Such zones should be treated as insecure. This has been fixed. [GL #2236]After a Negative Trust Anchor (NTA) is added, BIND performs periodic checks to see if it is still necessary. If BIND encountered a failure while creating a query to perform such a check, it attempted to dereference a
NULL
pointer, resulting in a crash. [GL #2244]A problem obtaining glue records could prevent a stub zone from functioning properly, if the authoritative server for the zone were configured for minimal responses. [GL #1736]
UV_EOF
is no longer treated as aTCP4RecvErr
or aTCP6RecvErr
. [GL #2208]
Notes for BIND 9.16.8¶
New Features¶
Add a new
rndc
command,rndc dnssec -rollover
, which triggers a manual rollover for a specific key. [GL #1749]Add a new
rndc
command,rndc dumpdb -expired
, which dumps the cache database, including expired RRsets that are awaiting cleanup, to thedump-file
for diagnostic purposes. [GL #1870]
Feature Changes¶
DNS Flag Day 2020: The default EDNS buffer size has been changed from 4096 to 1232 bytes. According to measurements done by multiple parties, this should not cause any operational problems as most of the Internet “core” is able to cope with IP message sizes between 1400-1500 bytes; the 1232 size was picked as a conservative minimal number that could be changed by the DNS operator to an estimated path MTU minus the estimated header space. In practice, the smallest MTU witnessed in the operational DNS community is 1500 octets, the maximum Ethernet payload size, so a useful default for maximum DNS/UDP payload size on reliable networks would be 1432 bytes. [GL #2183]
Bug Fixes¶
named
reported an invalid memory size when running in an environment that did not properly report the number of available memory pages and/or the size of each memory page. [GL #2166]With multiple forwarders configured,
named
could fail theREQUIRE(msg->state == (-1))
assertion inlib/dns/message.c
, causing it to crash. This has been fixed. [GL #2124]named
erroneously performed continuous key rollovers for KASP policies that used algorithm Ed25519 or Ed448 due to a mismatch between created key size and expected key size. [GL #2171]Updating contents of an RPZ zone which contained names spelled using varying letter case could cause some processing rules in that RPZ zone to be erroneously ignored. [GL #2169]
Notes for BIND 9.16.7¶
New Features¶
Add a new
rndc
command,rndc dnssec -checkds
, which signals tonamed
that a DS record for a given zone or key has been published or withdrawn from the parent. This command replaces the time-basedparent-registration-delay
configuration option. [GL #1613]Log when
named
adds a CDS/CDNSKEY to the zone. [GL #1748]
Bug Fixes¶
In rare circumstances,
named
would exit with an assertion failure when the number of nodes stored in the red-black tree exceeded the maximum allowed size of the internal hash table. [GL #2104]Silence spurious system log messages for an EPROTO(71) error code that was seen on older operating systems, where unhandled ICMPv6 errors resulted in a generic protocol error being returned instead of a more specific error code. [GL #1928]
With query name minimization enabled,
named
failed to resolveip6.arpa.
names that had extra labels to the left of the IPv6 part. For example, whennamed
attempted query name minimization on a name likeA.B.1.2.3.4.(...).ip6.arpa.
, it stopped at the leftmost IPv6 label, i.e.1.2.3.4.(...).ip6.arpa.
, without considering the extra labels (A.B
). That caused a query loop when resolving the name: ifnamed
received NXDOMAIN answers, then the same query was repeatedly sent until the number of queries sent reached the value of themax-recursion-queries
configuration option. [GL #1847]Parsing of LOC records was made more strict by rejecting a sole period (
.
) and/orm
as a value. These changes prevent zone files using such values from being loaded. Handling of negative altitudes which are not integers was also corrected. [GL #2074]Several problems found by OSS-Fuzz were fixed. (None of these are security issues.) [GL !3953] [GL !3975]
Notes for BIND 9.16.6¶
Security Fixes¶
It was possible to trigger an assertion failure by sending a specially crafted large TCP DNS message. This was disclosed in CVE-2020-8620.
ISC would like to thank Emanuel Almeida of Cisco Systems, Inc. for bringing this vulnerability to our attention. [GL #1996]
named
could crash after failing an assertion check in certain query resolution scenarios where QNAME minimization and forwarding were both enabled. To prevent such crashes, QNAME minimization is now always disabled for a given query resolution process, if forwarders are used at any point. This was disclosed in CVE-2020-8621.ISC would like to thank Joseph Gullo for bringing this vulnerability to our attention. [GL #1997]
It was possible to trigger an assertion failure when verifying the response to a TSIG-signed request. This was disclosed in CVE-2020-8622.
ISC would like to thank Dave Feldman, Jeff Warren, and Joel Cunningham of Oracle for bringing this vulnerability to our attention. [GL #2028]
When BIND 9 was compiled with native PKCS#11 support, it was possible to trigger an assertion failure in code determining the number of bits in the PKCS#11 RSA public key with a specially crafted packet. This was disclosed in CVE-2020-8623.
ISC would like to thank Lyu Chiy for bringing this vulnerability to our attention. [GL #2037]
update-policy
rules of typesubdomain
were incorrectly treated aszonesub
rules, which allowed keys used insubdomain
rules to update names outside of the specified subdomains. The problem was fixed by making suresubdomain
rules are again processed as described in the ARM. This was disclosed in CVE-2020-8624.ISC would like to thank Joop Boonen of credativ GmbH for bringing this vulnerability to our attention. [GL #2055]
New Features¶
A new configuration option
stale-cache-enable
has been introduced to enable or disable keeping stale answers in cache. [GL #1712]
Feature Changes¶
BIND’s cache database implementation has been updated to use a faster hash function with better distribution. In addition, the effective
max-cache-size
(configured explicitly, defaulting to a value based on system memory or set tounlimited
) now pre-allocates fixed-size hash tables. This prevents interruption to query resolution when the hash table sizes need to be increased. [GL #1775]Resource records received with 0 TTL are no longer kept in the cache to be used for stale answers. [GL #1829]
Bug Fixes¶
Wildcard RPZ passthru rules could incorrectly be overridden by other rules that were loaded from RPZ zones which appeared later in the
response-policy
statement. This has been fixed. [GL #1619]The IPv6 Duplicate Address Detection (DAD) mechanism could inadvertently prevent
named
from binding to new IPv6 interfaces, by causing multiple route socket messages to be sent for each IPv6 address.named
monitors for new interfaces tobind()
to when it is configured to listen onany
or on a specific range of addresses. New IPv6 interfaces can be in a “tentative” state before they are fully available for use. When DAD is in use, two messages are emitted by the route socket: one when the interface first appears and then a second one when it is fully “up.” An attempt bynamed
tobind()
to the new interface prematurely would fail, causing it thereafter to ignore that address/interface. The problem was worked around by setting theIP_FREEBIND
option on the socket and trying tobind()
to each IPv6 address again if the firstbind()
call for that address failed withEADDRNOTAVAIL
. [GL #2038]Addressed an error in recursive clients stats reporting which could cause underflow, and even negative statistics. There were occasions when an incoming query could trigger a prefetch for some eligible RRset, and if the prefetch code were executed before recursion, no increment in recursive clients stats would take place. Conversely, when processing the answers, if the recursion code were executed before the prefetch, the same counter would be decremented without a matching increment. [GL #1719]
The introduction of KASP support inadvertently caused the second field of
sig-validity-interval
to always be calculated in hours, even in cases when it should have been calculated in days. This has been fixed. (Thanks to Tony Finch.) [GL !3735]LMDB locking code was revised to make
rndc reconfig
work properly on FreeBSD and with LMDB >= 0.9.26. [GL #1976]
Notes for BIND 9.16.5¶
New Features¶
New
rndc
commandrndc dnssec -status
shows the current DNSSEC policy and keys in use, the key states, and rollover status. [GL #1612]
Bug Fixes¶
A race condition could occur if a TCP socket connection was closed while
named
was waiting for a recursive response. The attempt to send a response over the closing connection triggered an assertion failure in the functionisc__nm_tcpdns_send()
. [GL #1937]A race condition could occur when
named
attempted to use a UDP interface that was shutting down. This triggered an assertion failure inuv__udp_finish_close()
. [GL #1938]Fix assertion failure when server was under load and root zone had not yet been loaded. [GL #1862]
named
could crash when cleaning dead nodes inlib/dns/rbtdb.c
that were being reused. [GL #1968]named
crashed on shutdown when a newrndc
connection was received during shutdown. This has been fixed. [GL #1747]The DS RRset returned by
dns_keynode_dsset()
was used in a non-thread-safe manner. This could result in an INSIST being triggered. [GL #1926]Properly handle missing
kyua
command so thatmake check
does not fail unexpectedly when CMocka is installed, but Kyua is not. [GL #1950]The
primary
andsecondary
keywords, when used as parameters forcheck-names
, were not processed correctly and were being ignored. [GL #1949]rndc dnstap -roll <value>
did not limit the number of saved files to<value>
. [GL !3728]The validator could fail to accept a properly signed RRset if an unsupported algorithm appeared earlier in the DNSKEY RRset than a supported algorithm. It could also stop if it detected a malformed public key. [GL #1689]
The
blackhole
ACL was inadvertently disabled for client queries. Blocked IP addresses were not used for upstream queries but queries from those addresses could still be answered. [GL #1936]
Notes for BIND 9.16.4¶
Security Fixes¶
It was possible to trigger an assertion when attempting to fill an oversized TCP buffer. This was disclosed in CVE-2020-8618. [GL #1850]
It was possible to trigger an INSIST failure when a zone with an interior wildcard label was queried in a certain pattern. This was disclosed in CVE-2020-8619. [GL #1111] [GL #1718]
New Features¶
Documentation was converted from DocBook to reStructuredText. The BIND 9 ARM is now generated using Sphinx and published on Read the Docs. Release notes are no longer available as a separate document accompanying a release. [GL #83]
named
andnamed-checkzone
now reject master zones that have a DS RRset at the zone apex. Attempts to add DS records at the zone apex via UPDATE will be logged but otherwise ignored. DS records belong in the parent zone, not at the zone apex. [GL #1798]dig
and other tools can now print the Extended DNS Error (EDE) option when it appears in a request or a response. [GL #1835]
Feature Changes¶
The default value of
max-stale-ttl
has changed from 1 week to 12 hours. This option controls how longnamed
retains expired RRsets in cache as a potential mitigation mechanism, should there be a problem with one or more domains. Note that cache content retention is independent of whether stale answers are used in response to client queries (stale-answer-enable yes|no
andrndc serve-stale on|off
). Serving of stale answers when the authoritative servers are not responding must be explicitly enabled, whereas the retention of expired cache content takes place automatically on all versions of BIND 9 that have this feature available. [GL #1877]Warning
This change may be significant for administrators who expect that stale cache content will be automatically retained for up to 1 week. Add option
max-stale-ttl 1w;
tonamed.conf
to keep the previous behavior ofnamed
.listen-on-v6 { any; }
creates a separate socket for each interface. Previously, just one socket was created on systems conforming to RFC 3493 and RFC 3542. This change was introduced in BIND 9.16.0, but it was accidentally omitted from documentation. [GL #1782]
Bug Fixes¶
When fully updating the NSEC3 chain for a large zone via IXFR, a temporary loss of performance could be experienced on the secondary server when answering queries for nonexistent data that required DNSSEC proof of non-existence (in other words, queries that required the server to find and to return NSEC3 data). The unnecessary processing step that was causing this delay has now been removed. [GL #1834]
named
could crash with an assertion failure if the name of a database node was looked up while the database was being modified. [GL #1857]A possible deadlock in
lib/isc/unix/socket.c
was fixed. [GL #1859]Previously,
named
did not destroy some mutexes and conditional variables in netmgr code, which caused a memory leak on FreeBSD. This has been fixed. [GL #1893]A data race in
lib/dns/resolver.c:log_formerr()
that could lead to an assertion failure was fixed. [GL #1808]Previously,
provide-ixfr no;
failed to return up-to-date responses when the serial number was greater than or equal to the current serial number. [GL #1714]A bug in dnssec-policy keymgr was fixed, where the check for the existence of a given key’s successor would incorrectly return
true
if any other key in the keyring had a successor. [GL #1845]With dnssec-policy, when creating a successor key, the “goal” state of the current active key (the predecessor) was not changed and thus never removed from the zone. [GL #1846]
named-checkconf -p
could include spurious text inserver-addresses
statements due to an uninitialized DSCP value. This has been fixed. [GL #1812]The ARM has been updated to indicate that the TSIG session key is generated when named starts, regardless of whether it is needed. [GL #1842]
Notes for BIND 9.16.3¶
Known Issues¶
BIND crashes on startup when linked against libuv 1.36. This issue is related to
recvmmsg()
support in libuv, which was first included in libuv 1.35. The problem was addressed in libuv 1.37, but the relevant libuv code change requires a special flag to be set during library initialization in order forrecvmmsg()
support to be enabled. This BIND release sets that special flag when required, sorecvmmsg()
support is now enabled when BIND is compiled against either libuv 1.35 or libuv 1.37+; libuv 1.36 is still not usable with BIND. [GL #1761] [GL #1797]
Feature Changes¶
BIND 9 no longer sets receive/send buffer sizes for UDP sockets, relying on system defaults instead. [GL #1713]
The default rwlock implementation has been changed back to the native BIND 9 rwlock implementation. [GL #1753]
The native PKCS#11 EdDSA implementation has been updated to PKCS#11 v3.0 and thus made operational again. Contributed by Aaron Thompson. [GL !3326]
The OpenSSL ECDSA implementation has been updated to support PKCS#11 via OpenSSL engine (see engine_pkcs11 from libp11 project). [GL #1534]
The OpenSSL EdDSA implementation has been updated to support PKCS#11 via OpenSSL engine. Please note that an EdDSA-capable OpenSSL engine is required and thus this code is only a proof-of-concept for the time being. Contributed by Aaron Thompson. [GL #1763]
Message IDs in inbound AXFR transfers are now checked for consistency. Log messages are emitted for streams with inconsistent message IDs. [GL #1674]
The zone timers are now exported to the statistics channel. For the primary zones, only the loaded time is exported. For the secondary zones, the exported timers also include expire and refresh times. Contributed by Paul Frieden, Verizon Media. [GL #1232]
Bug Fixes¶
A bug in dnstap initialization could prevent some dnstap data from being logged, especially on recursive resolvers. [GL #1795]
When running on a system with support for Linux capabilities,
named
drops root privileges very soon after system startup. This was causing a spurious log message,unable to set effective uid to 0: Operation not permitted
, which has now been silenced. [GL #1042] [GL #1090]When
named-checkconf
was run, it would sometimes incorrectly set its exit code. It reflected only the status of the last view found; any errors found for other configured views were not reported. Thanks to Graham Clinch. [GL #1807]When built without LMDB support,
named
failed to restart after a zone with a double quote (“) in its name was added withrndc addzone
. Thanks to Alberto Fernández. [GL #1695]
Notes for BIND 9.16.2¶
Security Fixes¶
DNS rebinding protection was ineffective when BIND 9 is configured as a forwarding DNS server. Found and responsibly reported by Tobias Klein.:gl:#1574
Known Issues¶
We have received reports that in some circumstances, receipt of an IXFR can cause the processing of queries to slow significantly. Some of these were related to RPZ processing, which has been fixed in this release (see below). Others appear to occur where there are NSEC3-related changes (such as an operator changing the NSEC3 salt used in the hash calculation). These are being investigated. [GL #1685]
Feature Changes¶
The previous DNSSEC sign statistics used lots of memory. The number of keys to track is reduced to four per zone, which should be enough for 99% of all signed zones. [GL #1179]
Bug Fixes¶
When an RPZ policy zone was updated via zone transfer and a large number of records was deleted,
named
could become nonresponsive for a short period while deleted names were removed from the RPZ summary database. This database cleanup is now done incrementally over a longer period of time, reducing such delays. [GL #1447]When trying to migrate an already-signed zone from
auto-dnssec maintain
to one based ondnssec-policy
, the existing keys were immediately deleted and replaced with new ones. As the key rollover timing constraints were not being followed, it was possible that some clients would not have been able to validate responses until all old DNSSEC information had timed out from caches. BIND now looks at the time metadata of the existing keys and incorporates it into its DNSSEC policy operation. [GL #1706]
Notes for BIND 9.16.1¶
Known Issues¶
UDP network ports used for listening can no longer simultaneously be used for sending traffic. An example configuration which triggers this issue would be one which uses the same address:port pair for
listen-on(-v6)
statements as fornotify-source(-v6)
ortransfer-source(-v6)
. While this issue affects all operating systems, it only triggers log messages (e.g. “unable to create dispatch for reserved port”) on some of them. There are currently no plans to make such a combination of settings work again.
Feature Changes¶
The system-provided POSIX Threads read-write lock implementation is now used by default instead of the native BIND 9 implementation. Please be aware that glibc versions 2.26 through 2.29 had a bug that could cause BIND 9 to deadlock. A fix was released in glibc 2.30, and most current Linux distributions have patched or updated glibc, with the notable exception of Ubuntu 18.04 (Bionic) which is a work in progress. If you are running on an affected operating system, compile BIND 9 with
--disable-pthread-rwlock
until a fixed version of glibc is available. [GL !3125]
Notes for BIND 9.16.0¶
Note: this section only lists changes from BIND 9.14 (the previous stable branch of BIND).
New Features¶
A new asynchronous network communications system based on
libuv
is now used bynamed
for listening for incoming requests and responding to them. This change will make it easier to improve performance and implement new protocol layers (for example, DNS over TLS) in the future. [GL #29]The new
dnssec-policy
option allows the configuration of a key and signing policy (KASP) for zones. This option enablesnamed
to generate new keys as needed and automatically roll both ZSK and KSK keys. (Note that the syntax for this statement differs from the DNSSEC policy used bydnssec-keymgr
.) [GL #1134]In order to clarify the configuration of DNSSEC keys, the
trusted-keys
andmanaged-keys
statements have been deprecated, and the newtrust-anchors
statement should now be used for both types of key.When used with the keyword
initial-key
,trust-anchors
has the same behavior asmanaged-keys
, i.e., it configures a trust anchor that is to be maintained via RFC 5011.When used with the new keyword
static-key
,trust-anchors
has the same behavior astrusted-keys
, i.e., it configures a permanent trust anchor that will not automatically be updated. (This usage is not recommended for the root key.) [GL #6]Two new keywords have been added to the
trust-anchors
statement:initial-ds
andstatic-ds
. These allow the use of trust anchors in DS format instead of DNSKEY format. DS format allows trust anchors to be configured for keys that have not yet been published; this is the format used by IANA when announcing future root keys.As with the
initial-key
andstatic-key
keywords,initial-ds
configures a dynamic trust anchor to be maintained via RFC 5011, andstatic-ds
configures a permanent trust anchor. [GL #6] [GL #622]dig
,mdig
anddelv
can all now take a+yaml
option to print output in a detailed YAML format. [GL #1145]dig
now has a new command line option:+[no]unexpected
. By default,dig
won’t accept a reply from a source other than the one to which it sent the query. Add the+unexpected
argument to enable it to process replies from unexpected sources. [RT #44978]dig
now accepts a new command line option,+[no]expandaaaa
, which causes the IPv6 addresses in AAAA records to be printed in full 128-bit notation rather than the default RFC 5952 format. [GL #765]Statistics channel groups can now be toggled. [GL #1030]
Feature Changes¶
When static and managed DNSSEC keys were both configured for the same name, or when a static key was used to configure a trust anchor for the root zone and
dnssec-validation
was set to the default value ofauto
, automatic RFC 5011 key rollovers would be disabled. This combination of settings was never intended to work, but there was no check for it in the parser. This has been corrected, and it is now a fatal configuration error. [GL #868]DS and CDS records are now generated with SHA-256 digests only, instead of both SHA-1 and SHA-256. This affects the default output of
dnssec-dsfromkey
, thedsset
files generated bydnssec-signzone
, the DS records added to a zone bydnssec-signzone
based onkeyset
files, the CDS records added to a zone bynamed
anddnssec-signzone
based on “sync” timing parameters in key files, and the checks performed bydnssec-checkds
. [GL #1015]named
will now log a warning if a static key is configured for the root zone. [GL #6]A SipHash 2-4 based DNS Cookie (RFC 7873) algorithm has been added and made default. Old non-default HMAC-SHA based DNS Cookie algorithms have been removed, and only the default AES algorithm is being kept for legacy reasons. This change has no operational impact in most common scenarios. [GL #605]
If you are running multiple DNS servers (different versions of BIND 9 or DNS servers from multiple vendors) responding from the same IP address (anycast or load-balancing scenarios), make sure that all the servers are configured with the same DNS Cookie algorithm and same Server Secret for the best performance.
The information from the
dnssec-signzone
anddnssec-verify
commands is now printed to standard output. The standard error output is only used to print warnings and errors, and in case the user requests the signed zone to be printed to standard output with the-f -
option. A new configuration option-q
has been added to silence all output on standard output except for the name of the signed zone. [GL #1151]The DNSSEC validation code has been refactored for clarity and to reduce code duplication. [GL #622]
Compile-time settings enabled by the
--with-tuning=large
option forconfigure
are now in effect by default. Previously used default compile-time settings can be enabled by passing--with-tuning=small
toconfigure
. [GL !2989]JSON-C is now the only supported library for enabling JSON support for BIND statistics. The
configure
option has been renamed from--with-libjson
to--with-json-c
. Set thePKG_CONFIG_PATH
environment variable accordingly to specify a custom path to thejson-c
library, as the newconfigure
option does not take the library installation path as an optional argument. [GL #855]./configure
no longer sets--sysconfdir
to/etc
or--localstatedir
to/var
when--prefix
is not specified and the aforementioned options are not specified explicitly. Instead, Autoconf’s defaults of$prefix/etc
and$prefix/var
are respected. [GL #658]
Removed Features¶
The
dnssec-enable
option has been obsoleted and no longer has any effect. DNSSEC responses are always enabled if signatures and other DNSSEC data are present. [GL #866]DNSSEC Lookaside Validation (DLV) is now obsolete. The
dnssec-lookaside
option has been marked as deprecated; when used innamed.conf
, it will generate a warning but will otherwise be ignored. All code enabling the use of lookaside validation has been removed from the validator,delv
, and the DNSSEC tools. [GL #7]The
cleaning-interval
option has been removed. [GL !1731]
License¶
BIND 9 is open source software licensed under the terms of the Mozilla
Public License, version 2.0 (see the LICENSE
file for the full
text).
The license requires that if you make changes to BIND and distribute them outside your organization, those changes must be published under the same license. It does not require that you publish or disclose anything other than the changes you have made to our software. This requirement does not affect anyone who is using BIND, with or without modifications, without redistributing it, nor anyone redistributing BIND without changes.
Those wishing to discuss license compliance may contact ISC at https://www.isc.org/contact/.
End of Life¶
BIND 9.16 (Extended Support Version) will be supported until at least December, 2023. See https://kb.isc.org/docs/aa-00896 for details of ISC’s software support policy.