This document summarizes changes since the last production release of BIND on the corresponding major release branch.
The latest versions of BIND 9 software can always be found at http://www.isc.org/downloads/. There you will find additional information about each release, source code, and pre-compiled versions for Microsoft Windows operating systems.
Insufficient testing when parsing a message allowed records with an incorrect class to be be accepted, triggering a REQUIRE failure when those records were subsequently cached. This flaw is disclosed in CVE-2015-8000. [RT #40987]
Incorrect reference counting could result in an INSIST failure if a socket error occurred while performing a lookup. This flaw is disclosed in CVE-2015-8461. [RT#40945]
An incorrect boundary check in the OPENPGPKEY rdatatype could trigger an assertion failure. This flaw is disclosed in CVE-2015-5986. [RT #40286]
A buffer accounting error could trigger an assertion failure when parsing certain malformed DNSSEC keys.
This flaw was discovered by Hanno Böck of the Fuzzing Project, and is disclosed in CVE-2015-5722. [RT #40212]
A specially crafted query could trigger an assertion failure in message.c.
This flaw was discovered by Jonathan Foote, and is disclosed in CVE-2015-5477. [RT #40046]
On servers configured to perform DNSSEC validation, an assertion failure could be triggered on answers from a specially configured server.
This flaw was discovered by Breno Silveira Soares, and is disclosed in CVE-2015-4620. [RT #39795]
On servers configured to perform DNSSEC validation using managed trust anchors (i.e., keys configured explicitly via managed-keys, or implicitly via dnssec-validation auto; or dnssec-lookaside auto;), revoking a trust anchor and sending a new untrusted replacement could cause named to crash with an assertion failure. This could occur in the event of a botched key rollover, or potentially as a result of a deliberate attack if the attacker was in position to monitor the victim's DNS traffic.
This flaw was discovered by Jan-Piet Mens, and is disclosed in CVE-2015-1349. [RT #38344]
A flaw in delegation handling could be exploited to put named into an infinite loop, in which each lookup of a name server triggered additional lookups of more name servers. This has been addressed by placing limits on the number of levels of recursion named will allow (default 7), and on the number of queries that it will send before terminating a recursive query (default 50).
The recursion depth limit is configured via the
max-recursion-depth
option, and the query limit
via the max-recursion-queries
option.
The flaw was discovered by Florian Maury of ANSSI, and is disclosed in CVE-2014-8500. [RT #37580]
Two separate problems were identified in BIND's GeoIP code that
could lead to an assertion failure. One was triggered by use of
both IPv4 and IPv6 address families, the other by referencing
a GeoIP database in named.conf
which was
not installed. Both are covered by CVE-2014-8680. [RT #37672]
[RT #37679]
A less serious security flaw was also found in GeoIP: changes
to the geoip-directory option in
named.conf
were ignored when running
rndc reconfig. In theory, this could allow
named to allow access to unintended clients.
Added support for DynDB, a new interface for loading zone data from an external database, developed by Red Hat for the FreeIPA project. (Thanks in particular to Adam Tkac and Petr Spacek of Red Hat for the contribution.)
Unlike the existing DLZ and SDB interfaces, which provide a limited subset of database functionality within BIND — translating DNS queries into real-time database lookups with relatively poor performance and with no ability to handle DNSSEC-signed data — DynDB is able to fully implement and extend the database API used natively by BIND.
A DynDB module could pre-load data from an external data source, then serve it with the same performance and functionality as conventional BIND zones, and with the ability to take advantage of database features not available in BIND, such as multi-master replication.
New quotas have been added to limit the queries that are sent by recursive resolvers to authoritative servers experiencing denial-of-service attacks. When configured, these options can both reduce the harm done to authoritative servers and also avoid the resource exhaustion that can be experienced by recursives when they are being used as a vehicle for such an attack.
fetches-per-server
limits the number of
simultaneous queries that can be sent to any single
authoritative server. The configured value is a starting
point; it is automatically adjusted downward if the server is
partially or completely non-responsive. The algorithm used to
adjust the quota can be configured via the
fetch-quota-params
option.
fetches-per-zone
limits the number of
simultaneous queries that can be sent for names within a
single domain. (Note: Unlike "fetches-per-server", this
value is not self-tuning.)
Statistics counters have also been added to track the number of queries affected by these quotas.
Added support for dnstap, a fast, flexible method for capturing and logging DNS traffic, developed by Robert Edmonds at Farsight Security, Inc., whose assistance is gratefully acknowledged.
To enable dnstap at compile time,
the fstrm and protobuf-c
libraries must be available, and BIND must be configured with
--enable-dnstap
.
A new utility dnstap-read has been added to allow dnstap data to be presented in a human-readable format.
For more information on dnstap, see http://dnstap.info.
New statistics counters have been added to track traffic sizes, as specified in RSSAC002. Query and response message sizes are broken up into ranges of histogram buckets: TCP and UDP queries of size 0-15, 16-31, ..., 272-288, and 288+, and TCP and UDP responses of size 0-15, 16-31, ..., 4080-4095, and 4096+. These values can be accessed via the XML and JSON statistics channels at, for example, http://localhost:8888/xml/v3/traffic or http://localhost:8888/json/v1/traffic.
The serial number of a dynamically updatable zone can
now be set using
rndc signing -serial number
zonename
.
This is particularly useful with inline-signing
zones that have been reset. Setting the serial number to a value
larger than that on the slaves will trigger an AXFR-style
transfer.
When answering recursive queries, SERVFAIL responses can now be
cached by the server for a limited time; subsequent queries for
the same query name and type will return another SERVFAIL until
the cache times out. This reduces the frequency of retries
when a query is persistently failing, which can be a burden
on recursive serviers. The SERVFAIL cache timeout is controlled
by servfail-ttl
, which defaults to 1 second
and has an upper limit of 30.
The new rndc nta command can now be used to
set a "negative trust anchor" (NTA), disabling DNSSEC validation for
a specific domain; this can be used when responses from a domain
are known to be failing validation due to administrative error
rather than because of a spoofing attack. NTAs are strictly
temporary; by default they expire after one hour, but can be
configured to last up to one week. The default NTA lifetime
can be changed by setting the nta-lifetime
in
named.conf
. When added, NTAs are stored in a
file (
)
in order to persist across restarts of the named server.
viewname
.nta
The EDNS Client Subnet (ECS) option is now supported for
authoritative servers; if a query contains an ECS option then
ACLs containing geoip
or ecs
elements can match against the the address encoded in the option.
This can be used to select a view for a query, so that different
answers can be provided depending on the client network.
The EDNS EXPIRE option has been implemented on the client side, allowing a slave server to set the expiration timer correctly when transferring zone data from another slave server.
A new masterfile-style
zone option controls
the formatting of text zone files: When set to
full
, the zone file will dumped in
single-line-per-record format.
dig +ednsopt can now be used to set arbitrary EDNS options in DNS requests.
dig +ednsflags can now be used to set yet-to-be-defined EDNS flags in DNS requests.
dig +[no]ednsnegotiation can now be used enable / disable EDNS version negotiation.
dig +header-only can now be used to send queries without a question section.
dig +ttlunits causes dig to print TTL values with time-unit suffixes: w, d, h, m, s for weeks, days, hours, minutes, and seconds.
dig +zflag can be used to set the last unassigned DNS header flag bit. This bit in normally zero.
dig +dscp=value
can now be used to set the DSCP code point in outgoing query
packets.
dig +mapped can now be used to determine if mapped IPv4 addresses can be used.
serial-update-method
can now be set to
date
. On update, the serial number will
be set to the current date in YYYYMMDDNN format.
dnssec-signzone -N date also sets the serial number to YYYYMMDDNN.
named -L filename
causes named to send log messages to the specified file by
default instead of to the system log.
The rate limiter configured by the
serial-query-rate
option no longer covers
NOTIFY messages; those are now separately controlled by
notify-rate
and
startup-notify-rate
(the latter of which
controls the rate of NOTIFY messages sent when the server
is first started up or reconfigured).
The default number of tasks and client objects available
for serving lightweight resolver queries have been increased,
and are now configurable via the new lwres-tasks
and lwres-clients
options in
named.conf
. [RT #35857]
Log output to files can now be buffered by specifying buffered yes; when creating a channel.
delv +tcp will exclusively use TCP when sending queries.
named will now check to see whether
other name server processes are running before starting up.
This is implemented in two ways: 1) by refusing to start
if the configured network interfaces all return "address
in use", and 2) by attempting to acquire a lock on a file
specified by the lock-file
option or
the -X command line option. The
default lock file is
/var/run/named/named.lock
.
Specifying none
will disable the lock
file check.
rndc delzone can now be applied to zones
which were configured in named.conf
;
it is no longer restricted to zones which were added by
rndc addzone. (Note, however, that
this does not edit named.conf
; the zone
must be removed from the configuration or it will return
when named is restarted or reloaded.)
rndc modzone can be used to reconfigure a zone, using similar syntax to rndc addzone.
rndc showzone displays the current configuration for a specified zone.
Added server-side support for pipelined TCP queries. Clients may continue sending queries via TCP while previous queries are processed in parallel. Responses are sent when they are ready, not necessarily in the order in which the queries were received.
To revert to the former behavior for a particular client address or range of addresses, specify the address prefix in the "keep-response-order" option. To revert to the former behavior for all clients, use "keep-response-order { any; };".
The new mdig command is a version of dig that sends multiple pipelined queries and then waits for responses, instead of sending one query and waiting the response before sending the next. [RT #38261]
To enable better monitoring and troubleshooting of RFC 5011 trust anchor management, the new rndc managed-keys can be used to check status of trust anchors or to force keys to be refreshed. Also, the managed-keys data file now has easier-to-read comments. [RT #38458]
An --enable-querytrace configure switch is now available to enable very verbose query tracelogging. This option can only be set at compile time. This option has a negative performance impact and should be used only for debugging. [RT #37520]
A new tcp-only option can be specified in server statements to force named to connect to the specified server via TCP. [RT #37800]
The nxdomain-redirect option specifies a DNS namespace to use for NXDOMAIN redirection. When a recursive lookup returns NXDOMAIN, a second lookup is initiated with the specified name appended to the query name. This allows NXDOMAIN redirection data to be supplied by multiple zones configured on the server or by recursive queries to other servers. (The older method, using a single type redirect zone, has better average performance but is less flexible.) [RT #37989]
The following types have been implemented: CSYNC, NINFO, RKEY, SINK, TA, TALINK.
A new message-compression option can be
used to specify whether or not to use name compression when
answering queries. Setting this to no
results in larger responses, but reduces CPU consumption and
may improve throughput. The default is yes
.
A "read-only" clause is now available for non-destructive control channel access. In such cases, a restricted set of rndc commands are allowed for querying information from named. By default, control channel access is read-write.
Updated the compiled in addresses for H.ROOT-SERVERS.NET.
ACLs containing geoip asnum elements were not correctly matched unless the full organization name was specified in the ACL (as in geoip asnum "AS1234 Example, Inc.";). They can now match against the AS number alone (as in geoip asnum "AS1234";).
When using native PKCS#11 cryptography (i.e., configure --enable-native-pkcs11) HSM PINs of up to 256 characters can now be used.
NXDOMAIN responses to queries of type DS are now cached separately from those for other types. This helps when using "grafted" zones of type forward, for which the parent zone does not contain a delegation, such as local top-level domains. Previously a query of type DS for such a zone could cause the zone apex to be cached as NXDOMAIN, blocking all subsequent queries. (Note: This change is only helpful when DNSSEC validation is not enabled. "Grafted" zones without a delegation in the parent are not a recommended configuration.)
Update forwarding performance has been improved by allowing a single TCP connection to be shared between multiple updates.
By default, nsupdate will now check the correctness of hostnames when adding records of type A, AAAA, MX, SOA, NS, SRV or PTR. This behavior can be disabled with check-names no.
Added support for OPENPGPKEY type.
The names of the files used to store managed keys and added
zones for each view are no longer based on the SHA256 hash
of the view name, except when this is necessary because the
view name contains characters that would be incompatible with use
as a file name. For views whose names do not contain forward
slashes ('/'), backslashes ('\'), or capital letters - which
could potentially cause namespace collision problems on
case-insensitive filesystems - files will now be named
after the view (for example, internal.mkeys
or external.nzf
). However, to ensure
consistent behavior when upgrading, if a file using the old
name format is found to exist, it will continue to be used.
"rndc" can now return text output of arbitrary size to the caller. (Prior to this, certain commands such as "rndc tsig-list" and "rndc zonestatus" could return truncated output.)
Errors reported when running rndc addzone (e.g., when a zone file cannot be loaded) have been clarified to make it easier to diagnose problems.
When encountering an authoritative name server whose name is an alias pointing to another name, the resolver treats this as an error and skips to the next server. Previously this happened silently; now the error will be logged to the newly-created "cname" log category.
If named is not configured to validate the answer then allow fallback to plain DNS on timeout even when we know the server supports EDNS. This will allow the server to potentially resolve signed queries when TCP is being blocked.
Large inline-signing changes should be less disruptive.
Signature generation is now done incrementally; the number
of signatures to be generated in each quantum is controlled
by "sig-signing-signatures number
;".
[RT #37927]
The experimental SIT option (code point 65001) of BIND 9.10.0 through BIND 9.10.2 has been replaced with the COOKIE option (code point 10). It is no longer experimental, and is sent by default, by both named and dig.
The SIT-related named.conf options have been marked as obsolete, and are otherwise ignored.
When dig receives a truncated (TC=1) response or a BADCOOKIE response code from a server, it will automatically retry the query using the server COOKIE that was returned by the server in its initial response. [RT #39047]
A alternative NXDOMAIN redirect method (nxdomain-redirect) which allows the redirect information to be looked up from a namespace on the Internet rather than requiring a zone to be configured on the server is now available.
Retrieving the local port range from net.ipv4.ip_local_port_range on Linux is now supported.
Within the response-policy
option, it is now
possible to configure RPZ rewrite logging on a per-zone basis
using the log
clause.
The default preferred glue is now the address type of the transport the query was received over.
On machines with 2 or more processors (CPU), the default value for the number of UDP listeners has been changed to the number of detected processors minus one.
Zone transfers now use smaller message sizes to improve message compression. This results in reduced network usage.
The Microsoft Windows install tool
BINDInstall.exe which requires a
non-free version of Visual Studio to be built, now uses two
files (lists of flags and files) created by the Configure
perl script with all the needed information which were
previously compiled in the binary. Read
win32utils/build.txt
for more details.
[RT #38915]
Some of the options for GeoIP ACLs, including "areacode", "metrocode", and "timezone", were incorrectly documented as "area", "metro" and "tz". Both the long and abbreviated versions are now accepted.
dig, host and nslookup aborted when encountering a name which, after appending search list elements, exceeded 255 bytes. Such names are now skipped, but processing of other names will continue. [RT #36892]
The error message generated when
named-checkzone or
named-checkconf -z encounters a
$TTL
directive without a value has
been clarified. [RT #37138]
Semicolon characters (;) included in TXT records were incorrectly escaped with a backslash when the record was displayed as text. This is actually only necessary when there are no quotation marks. [RT #37159]
When files opened for writing by named,
such as zone journal files, were referenced more than once
in named.conf
, it could lead to file
corruption as multiple threads wrote to the same file. This
is now detected when loading named.conf
and reported as an error. [RT #37172]
When checking for updates to trust anchors listed in
managed-keys
, named
now revalidates keys based on the current set of
active trust anchors, without relying on any cached
record of previous validation. [RT #37506]
Large-system tuning (configure --with-tuning=large) caused problems on some platforms by setting a socket receive buffer size that was too large. This is now detected and corrected at run time. [RT #37187]
When NXDOMAIN redirection is in use, queries for a name that is present in the redirection zone but a type that is not present will now return NOERROR instead of NXDOMAIN.
Due to an inadvertent removal of code in the previous release, when named encountered an authoritative name server which dropped all EDNS queries, it did not always try plain DNS. This has been corrected. [RT #37965]
A regression caused nsupdate to use the default recursive servers rather than the SOA MNAME server when sending the UPDATE.
Adjusted max-recursion-queries to accommodate the smaller initial packet sizes used in BIND 9.10 and higher when contacting authoritative servers for the first time.
Built-in "empty" zones did not correctly inherit the "allow-transfer" ACL from the options or view. [RT #38310]
Two leaks were fixed that could cause named processes to grow to very large sizes. [RT #38454]
Fixed some bugs in RFC 5011 trust anchor management, including a memory leak and a possible loss of state information. [RT #38458]
Asynchronous zone loads were not handled correctly when the zone load was already in progress; this could trigger a crash in zt.c. [RT #37573]
A race during shutdown or reconfiguration could cause an assertion failure in mem.c. [RT #38979]
Some answer formatting options didn't work correctly with dig +short. [RT #39291]
Several bugs have been fixed in the RPZ implementation:
Policy zones that did not specifically require recursion could be treated as if they did; consequently, setting qname-wait-recurse no; was sometimes ineffective. This has been corrected. In most configurations, behavioral changes due to this fix will not be noticeable. [RT #39229]
The server could crash if policy zones were updated (e.g. via rndc reload or an incoming zone transfer) while RPZ processing was still ongoing for an active query. [RT #39415]
On servers with one or more policy zones configured as slaves, if a policy zone updated during regular operation (rather than at startup) using a full zone reload, such as via AXFR, a bug could allow the RPZ summary data to fall out of sync, potentially leading to an assertion failure in rpz.c when further incremental updates were made to the zone, such as via IXFR. [RT #39567]
The server could match a shorter prefix than what was available in CLIENT-IP policy triggers, and so, an unexpected action could be taken. This has been corrected. [RT #39481]
The server could crash if a reload of an RPZ zone was initiated while another reload of the same zone was already in progress. [RT #39649]
Negative trust anchors (NTAs) were incorrectly deleted when the server was reloaded or reconfigured. [RT #41058]
Zones configured to use map format master files can't be used as policy zones because RPZ summary data isn't compiled when such zones are mapped into memory. This limitation may be fixed in a future release, but in the meantime it has been documented, and attempting to use such zones in response-policy statements is now a configuration error. [RT #38321]
The end of life for BIND 9.11 is yet to be determined but will not be before BIND 9.13.0 has been released for 6 months. https://www.isc.org/downloads/software-support-policy/
Thank you to everyone who assisted us in making this release possible. If you would like to contribute to ISC to assist us in continuing to make quality open source software, please visit our donations page at http://www.isc.org/donate/.