Release notes

Knot Resolver 3.1.0 (2018-11-02)

Incompatible changes

  • hints.use_nodata(true) by default; that’s what most users want
  • libknot >= 2.7.2 is required

Improvements

  • cache: handle out-of-space SIGBUS slightly better (#197)
  • daemon: improve TCP timeout handling (!686)

Bugfixes

  • cache.clear(‘name’): fix some edge cases in API (#401)
  • fix error handling from TLS writes (!669)
  • avoid SERVFAILs due to certain kind of NS dependency cycles (#374)

Knot Resolver 3.0.0 (2018-08-20)

Incompatible changes

  • cache: fail lua operations if cache isn’t open yet (!639) By default cache is opened after reading the configuration, and older versions were silently ignoring cache operations. Valid configuration must open cache using cache.open() or cache.size = before executing cache operations like cache.clear().
  • libknot >= 2.7.1 is required, which brings also larger API changes
  • in case you wrote custom Lua modules, please consult https://knot-resolver.readthedocs.io/en/latest/lib.html#incompatible-changes-since-3-0-0
  • in case you wrote custom C modules, please see compile against Knot DNS 2.7 and adjust your module according to messages from C compiler
  • DNS cookie module (RFC 7873) is not available in this release, it will be later reworked to reflect development in IEFT dnsop working group
  • version module was permanently removed because it was not really used by users; if you want to receive notifications abou new releases please subscribe to https://lists.nic.cz/cgi-bin/mailman/listinfo/knot-resolver-announce

Bugfixes

  • fix multi-process race condition in trust anchor maintenance (!643)
  • ta_sentinel: also consider static trust anchors not managed via RFC 5011

Improvements

  • reorder_RR() implementation is brought back
  • bring in performace improvements provided by libknot 2.7
  • cache.clear() has a new, more powerful API
  • cache documentation was improved
  • old name “Knot DNS Resolver” is replaced by unambiguous “Knot Resolver” to prevent confusion with “Knot DNS” authoritative server

Knot Resolver 2.4.1 (2018-08-02)

Security

  • fix CVE-2018-10920: Improper input validation bug in DNS resolver component (security!7, security!9)

Bugfixes

  • cache: fix TTL overflow in packet due to min_ttl (#388, security!8)
  • TLS session resumption: avoid bad scheduling of rotation (#385)
  • HTTP module: fix a regression in 2.4.0 which broke custom certs (!632)
  • cache: NSEC3 negative cache even without NS record (#384) This fixes lower hit rate in NSEC3 zones (since 2.4.0).
  • minor TCP and TLS fixes (!623, !624, !626)

Knot Resolver 2.4.0 (2018-07-03)

Incompatible changes

  • minimal libknot version is now 2.6.7 to pull in latest fixes (#366)

Security

  • fix a rare case of zones incorrectly dowgraded to insecure status (!576)

New features

  • TLS session resumption (RFC 5077), both server and client (!585, #105) (disabled when compiling with gnutls < 3.5)
  • TLS_FORWARD policy uses system CA certificate store by default (!568)
  • aggressive caching for NSEC3 zones (!600)
  • optional protection from DNS Rebinding attack (module rebinding, !608)
  • module bogus_log to log DNSSEC bogus queries without verbose logging (!613)

Bugfixes

  • prefill: fix ability to read certificate bundle (!578)
  • avoid turning off qname minimization in some cases, e.g. co.uk. (#339)
  • fix validation of explicit wildcard queries (#274)
  • dns64 module: more properties from the RFC implemented (incl. bug #375)

Improvements

  • systemd: multiple enabled kresd instances can now be started using kresd.target
  • ta_sentinel: switch to version 14 of the RFC draft (!596)
  • support for glibc systems with a non-Linux kernel (!588)
  • support per-request variables for Lua modules (!533)
  • support custom HTTP endpoints for Lua modules (!527)

Knot Resolver 2.3.0 (2018-04-23)

Security

  • fix CVE-2018-1110: denial of service triggered by malformed DNS messages (!550, !558, security!2, security!4)
  • increase resilience against slow lorris attack (security!5)

New features

  • new policy.REFUSE to reply REFUSED to clients

Bugfixes

  • validation: fix SERVFAIL in case of CNAME to NXDOMAIN in a single zone (!538)
  • validation: fix SERVFAIL for DS . query (!544)
  • lib/resolve: don’t send unecessary queries to parent zone (!513)
  • iterate: fix validation for zones where parent and child share NS (!543)
  • TLS: improve error handling and documentation (!536, !555, !559)

Improvements

  • prefill: new module to periodically import root zone into cache (replacement for RFC 7706, !511)
  • network_listen_fd: always create end point for supervisor supplied file descriptor
  • use CPPFLAGS build environment variable if set (!547)

Knot Resolver 2.2.0 (2018-03-28)

New features

  • cache server unavailability to prevent flooding unreachable servers (Please note that caching algorithm needs further optimization and will change in further versions but we need to gather operational experience first.)

Bugfixes

  • don’t magically -D_FORTIFY_SOURCE=2 in some cases
  • allow large responses for outbound over TCP
  • fix crash with RR sets with over 255 records

Knot Resolver 2.1.1 (2018-02-23)

Bugfixes

  • when iterating, avoid unnecessary queries for NS in insecure parent. This problem worsened in 2.0.0. (#246)
  • prevent UDP packet leaks when using TLS forwarding
  • fix the hints module also on some other systems, e.g. Gentoo.

Knot Resolver 2.1.0 (2018-02-16)

Incompatible changes

  • stats: remove tracking of expiring records (predict uses another way)
  • systemd: re-use a single kresd.socket and kresd-tls.socket
  • ta_sentinel: implement protocol draft-ietf-dnsop-kskroll-sentinel-01 (our draft-ietf-dnsop-kskroll-sentinel-00 implementation had inverted logic)
  • libknot: require version 2.6.4 or newer to get bugfixes for DNS-over-TLS

Bugfixes

  • detect_time_jump module: don’t clear cache on suspend-resume (#284)
  • stats module: fix stats.list() returning nothing, regressed in 2.0.0
  • policy.TLS_FORWARD: refusal when configuring with multiple IPs (#306)
  • cache: fix broken refresh of insecure records that were about to expire
  • fix the hints module on some systems, e.g. Fedora (came back on 2.0.0)
  • build with older gnutls (conditionally disable features)
  • fix the predict module to work with insecure records & cleanup code

Knot Resolver 2.0.0 (2018-01-31)

Incompatible changes

  • systemd: change unit files to allow running multiple instances, deployments with single instance now must use kresd@1.service instead of kresd.service; see kresd.systemd(7) for details
  • systemd: the directory for cache is now /var/cache/knot-resolver
  • unify default directory and user to knot-resolver
  • directory with trust anchor file specified by -k option must be writeable
  • policy module is now loaded by default to enforce RFC 6761; see documentation for policy.PASS if you use locally-served DNS zones
  • drop support for alternative cache backends memcached, redis, and for Lua bindings for some specific cache operations
  • REORDER_RR option is not implemented (temporarily)

New features

  • aggressive caching of validated records (RFC 8198) for NSEC zones; thanks to ICANN for sponsoring this work.
  • forwarding over TLS, authenticated by SPKI pin or certificate. policy.TLS_FORWARD pipelines queries out-of-order over shared TLS connection Beware: Some resolvers do not support out-of-order query processing. TLS forwarding to such resolvers will lead to slower resolution or failures.
  • trust anchors: you may specify a read-only file via -K or –keyfile-ro
  • trust anchors: at build-time you may set KEYFILE_DEFAULT (read-only)
  • ta_sentinel module implements draft ietf-dnsop-kskroll-sentinel-00, enabled by default
  • serve_stale module is prototype, subject to change
  • extended API for Lua modules

Bugfixes

  • fix build on osx - regressed in 1.5.3 (different linker option name)

Knot Resolver 1.5.3 (2018-01-23)

Bugfixes

  • fix the hints module on some systems, e.g. Fedora. Symptom: undefined symbol: engine_hint_root_file

Knot Resolver 1.5.2 (2018-01-22)

Security

  • fix CVE-2018-1000002: insufficient DNSSEC validation, allowing attackers to deny existence of some data by forging packets. Some combinations pointed out in RFC 6840 sections 4.1 and 4.3 were not taken into account.

Bugfixes

  • memcached: fix fallout from module rename in 1.5.1

Knot Resolver 1.5.1 (2017-12-12)

Incompatible changes

  • script supervisor.py was removed, please migrate to a real process manager
  • module ketcd was renamed to etcd for consistency
  • module kmemcached was renamed to memcached for consistency

Bugfixes

  • fix SIGPIPE crashes (#271)
  • tests: work around out-of-space for platforms with larger memory pages
  • lua: fix mistakes in bindings affecting 1.4.0 and 1.5.0 (and 1.99.1-alpha), potentially causing problems in dns64 and workarounds modules
  • predict module: various fixes (!399)

Improvements

  • add priming module to implement RFC 8109, enabled by default (#220)
  • add modules helping with system time problems, enabled by default; for details see documentation of detect_time_skew and detect_time_jump

Knot Resolver 1.5.0 (2017-11-02)

Bugfixes

  • fix loading modules on Darwin

Improvements

  • new module ta_signal_query supporting Signaling Trust Anchor Knowledge using Keytag Query (RFC 8145 section 5); it is enabled by default
  • attempt validation for more records but require it for fewer of them (e.g. avoids SERVFAIL when server adds extra records but omits RRSIGs)

Knot Resolver 1.99.1-alpha (2017-10-26)

This is an experimental release meant for testing aggressive caching. It contains some regressions and might (theoretically) be even vulnerable. The current focus is to minimize queries into the root zone.

Improvements

  • negative answers from validated NSEC (NXDOMAIN, NODATA)
  • verbose log is very chatty around cache operations (maybe too much)

Regressions

  • dropped support for alternative cache backends and for some specific cache operations
  • caching doesn’t yet work for various cases:
    • negative answers without NSEC (i.e. with NSEC3 or insecure)
      • +cd queries (needs other internal changes)
      • positive wildcard answers
  • spurious SERVFAIL on specific combinations of cached records, printing:
    <= bad keys, broken trust chain
  • make check
  • a few Deckard tests are broken, probably due to some problems above
  • also unknown ones?

Knot Resolver 1.4.0 (2017-09-22)

Incompatible changes

  • lua: query flag-sets are no longer represented as plain integers. kres.query.* no longer works, and kr_query_t lost trivial methods ‘hasflag’ and ‘resolved’. You can instead write code like qry.flags.NO_0X20 = true.

Bugfixes

  • fix exiting one of multiple forks (#150)
  • cache: change the way of using LMDB transactions. That in particular fixes some cases of using too much space with multiple kresd forks (#240).

Improvements

  • policy.suffix: update the aho-corasick code (#200)
  • root hints are now loaded from a zonefile; exposed as hints.root_file(). You can override the path by defining ROOTHINTS during compilation.
  • policy.FORWARD: work around resolvers adding unsigned NS records (#248)
  • reduce unneeded records previously put into authority in wildcarded answers

Knot Resolver 1.3.3 (2017-08-09)

Security

  • Fix a critical DNSSEC flaw. Signatures might be accepted as valid even if the signed data was not in bailiwick of the DNSKEY used to sign it, assuming the trust chain to that DNSKEY was valid.

Bugfixes

  • iterate: skip RRSIGs with bad label count instead of immediate SERVFAIL
  • utils: fix possible incorrect seeding of the random generator
  • modules/http: fix compatibility with the Prometheus text format

Improvements

  • policy: implement remaining special-use domain names from RFC6761 (#205), and make these rules apply only if no other non-chain rule applies

Knot Resolver 1.3.2 (2017-07-28)

Security

  • fix possible opportunities to use insecure data from cache as keys for validation

Bugfixes

  • daemon: check existence of config file even if rundir isn’t specified
  • policy.FORWARD and STUB: use RTT tracking to choose servers (#125, #208)
  • dns64: fix CNAME problems (#203) It still won’t work with policy.STUB.
  • hints: better interpretation of hosts-like files (#204)
    also, error out if a bad entry is encountered in the file
  • dnssec: handle unknown DNSKEY/DS algorithms (#210)
  • predict: fix the module, broken since 1.2.0 (#154)

Improvements

  • embedded LMDB fallback: update 0.9.18 -> 0.9.21

Knot Resolver 1.3.1 (2017-06-23)

Bugfixes

  • modules/http: fix finding the static files (bug from 1.3.0)
  • policy.FORWARD: fix some cases of CNAMEs obstructing search for zone cuts

Knot Resolver 1.3.0 (2017-06-13)

Security

  • Refactor handling of AD flag and security status of resource records. In some cases it was possible for secure domains to get cached as insecure, even for a TLD, leading to disabled validation. It also fixes answering with non-authoritative data about nameservers.

Improvements

  • major feature: support for forwarding with validation (#112). The old policy.FORWARD action now does that; the previous non-validating mode is still available as policy.STUB except that also uses caching (#122).
  • command line: specify ports via @ but still support # for compatibility
  • policy: recognize 100.64.0.0/10 as local addresses
  • layer/iterate: do retry repeatedly if REFUSED, as we can’t yet easily retry with other NSs while avoiding retrying with those who REFUSED
  • modules: allow changing the directory where modules are found, and do not search the default library path anymore.

Bugfixes

  • validate: fix insufficient caching for some cases (relatively rare)
  • avoid putting “duplicate” record-sets into the answer (#198)

Knot Resolver 1.2.6 (2017-04-24)

Security

  • dnssec: don’t set AD flag for NODATA answers if wildcard non-existence is not guaranteed due to opt-out in NSEC3

Improvements

  • layer/iterate: don’t retry repeatedly if REFUSED

Bugfixes

  • lib/nsrep: revert some changes to NS reputation tracking that caused severe problems to some users of 1.2.5 (#178 and #179)
  • dnssec: fix verification of wildcarded non-singleton RRsets
  • dnssec: allow wildcards located directly under the root
  • layer/rrcache: avoid putting answer records into queries in some cases

Knot Resolver 1.2.5 (2017-04-05)

Security

  • layer/validate: clear AD if closest encloser proof has opt-outed NSEC3 (#169)
  • layer/validate: check if NSEC3 records in wildcard expansion proof has an opt-out
  • dnssec/nsec: missed wildcard no-data answers validation has been implemented

Improvements

  • modules/dnstap: a DNSTAP support module (Contributed by Vicky Shrestha)
  • modules/workarounds: a module adding workarounds for known DNS protocol violators
  • layer/iterate: fix logging of glue addresses
  • kr_bitcmp: allow bits=0 and consequently 0.0.0.0/0 matches in view and renumber modules.
  • modules/padding: Improve default padding of responses (Contributed by Daniel Kahn Gillmor)
  • New kresc client utility (experimental; don’t rely on the API yet)

Bugfixes

  • trust anchors: Improve trust anchors storage format (#167)
  • trust anchors: support non-root TAs, one domain per file
  • policy.DENY: set AA flag and clear AD flag
  • lib/resolve: avoid unnecessary DS queries
  • lib/nsrep: don’t treat servers with NOIP4 + NOIP6 flags as timeouted
  • layer/iterate: During packet classification (answer vs. referral) don’t analyze AUTHORITY section in authoritative answer if ANSWER section contains records that have been requested

Knot Resolver 1.2.4 (2017-03-09)

Security

  • Knot Resolver 1.2.0 and higher could return AD flag for insecure answer if the daemon received answer with invalid RRSIG several times in a row.

Improvements

  • modules/policy: allow QTRACE policy to be chained with other policies
  • hints.add_hosts(path): a new property
  • module: document the API and simplify the code
  • policy.MIRROR: support IPv6 link-local addresses
  • policy.FORWARD: support IPv6 link-local addresses
  • add net.outgoing_{v4,v6} to allow specifying address to use for connections

Bugfixes

  • layer/iterate: some improvements in cname chain unrolling
  • layer/validate: fix duplicate records in AUTHORITY section in case of WC expansion proof
  • lua: do not truncate cache size to unsigned
  • forwarding mode: correctly forward +cd flag
  • fix a potential memory leak
  • don’t treat answers that contain DS non-existance proof as insecure
  • don’t store NSEC3 and their signatures in the cache
  • layer/iterate: when processing delegations, check if qname is at or below new authority

Knot Resolver 1.2.3 (2017-02-23)

Bugfixes

  • Disable storing GLUE records into the cache even in the (non-default) QUERY_PERMISSIVE mode
  • iterate: skip answer RRs that don’t match the query
  • layer/iterate: some additional processing for referrals
  • lib/resolve: zonecut fetching error was fixed

Knot Resolver 1.2.2 (2017-02-10)

Bugfixes:

  • Fix -k argument processing to avoid out-of-bounds memory accesses
  • lib/resolve: fix zonecut fetching for explicit DS queries
  • hints: more NULL checks
  • Fix TA bootstrapping for multiple TAs in the IANA XML file

Testing:

  • Update tests to run tests with and without QNAME minimization

Knot Resolver 1.2.1 (2017-02-01)

Security:

  • Under certain conditions, a cached negative answer from a CD query would be reused to construct response for non-CD queries, resulting in Insecure status instead of Bogus. Only 1.2.0 release was affected.

Documentation

  • Update the typo in the documentation: The query trace policy is named policy.QTRACE (and not policy.TRACE)

Bugfixes:

  • lua: make the map command check its arguments

Knot Resolver 1.2.0 (2017-01-24)

Security:

  • In a policy.FORWARD() mode, the AD flag was being always set by mistake. It is now cleared, as the policy.FORWARD() doesn’t do DNSSEC validation yet.

Improvements:

  • The DNSSEC Validation has been refactored, fixing many resolving failures.
  • Add module version that checks for updates and CVEs periodically.
  • Support RFC7830: EDNS(0) padding in responses over TLS.
  • Support CD flag on incoming requests.
  • hints module: previously /etc/hosts was loaded by default, but not anymore. Users can now actually avoid loading any file.
  • DNS over TLS now creates ephemeral certs.
  • Configurable cache.{min,max}_tll option, with max_ttl defaulting to 6 days.
  • Option to reorder RRs in the response.
  • New policy.QTRACE policy to print packet contents

Bugfixes:

  • Trust Anchor configuration is now more robust.
  • Correctly answer NOTIMPL for meta-types and non-IN RR classes.
  • Free TCP buffer on cancelled connection.
  • Fix crash in hints module on empty hints file, and fix non-lowercase hints.

Miscellaneous:

  • It now requires knot >= 2.3.1 to link successfully.
  • The API+ABI for modules changed slightly.
  • New LRU implementation.

Knot Resolver 1.1.1 (2016-08-24)

Bugfixes:

  • Fix 0x20 randomization with retransmit
  • Fix pass-through for the stub mode
  • Fix the root hints IPv6 addresses
  • Fix dst addr for retries over TCP

Improvements:

  • Track RTT of all tried servers for faster retransmit
  • DAF: Allow forwarding to custom port
  • systemd: Read EnvironmentFile and user $KRESD_ARGS
  • systemd: Update systemd units to be named after daemon

Knot Resolver 1.1.0 (2016-08-12)

Improvements:

  • RFC7873 DNS Cookies
  • RFC7858 DNS over TLS
  • HTTP/2 web interface, RESTful API
  • Metrics exported in Prometheus
  • DNS firewall module
  • Explicit CNAME target fetching in strict mode
  • Query minimisation improvements
  • Improved integration with systemd

Knot Resolver 1.0.0 (2016-05-30)

Initial release:

  • The first initial release