Recursor 3.6.2

Note
Version 3.6.2 is a bugfix update to 3.6.1. Released on the 30th of October 2014.

Official download page

A list of changes since 3.6.1 follows.

  • commit ab14b4f: expedite servfail generation for ezdns-like failures (fully abort query resolving if we hit more than 50 outqueries)
  • commit 42025be: PowerDNS now polls the security status of a release at startup and periodically. More detail on this feature, and how to turn it off, can be found in Section 2, “Security polling”.
  • commit 5027429: We did not transmit the right ‘local’ socket address to Lua for TCP/IP queries in the recursor. In addition, we would attempt to lookup a filedescriptor that wasn’t there in an unlocked map which could conceivably lead to crashes. Closes ticket 1828, thanks Winfried for reporting
  • commit 752756c: Sync embedded yahttp copy. API: Replace HTTP Basic auth with static key in custom header
  • commit 6fdd40d: add missing #include <pthread.h> to rec-channel.hh (this fixes building on OS X).

Authoritative Server 3.4.1

Warning
Version 3.4.1. of the PowerDNS Authoritative Server is a major upgrade if you are coming from 2.9.x. Additionally, if you are coming from any 3.x version (including 3.3.1), there is a mandatory SQL schema upgrade. Please refer toSection 6, “From PowerDNS Authoritative Server 3.3.1 to 3.4.0” and any relevant sections before it, before deploying this version. There are no 3.4.1 upgrade notes.
[Note] Note
Released October 30th, 2014

Find the downloads on our download page.

This is a bugfix update to 3.4.0 and any earlier version.

A list of changes since 3.4.0 follows.

PowerDNS Security Status Polling

PowerDNS software sadly sometimes has critical security bugs. Even though we send out notifications of these via all channels available, our recent security releases have taught us that not everybody actually finds out about important security updates via our mailing lists, Facebook and Twitter.

To solve this, the development versions of PowerDNS software have been updated to  poll for security notifications over DNS, and log these periodically. Secondly, the security status of the software is available for monitoring using the built-in metrics. This allows operators to poll for the PowerDNS security status and alert on it.

In the implementation of this idea, we have taken the unique role of operating system distributors into account. Specifically, we can deal with backported security fixes.

This feature can easily be disabled, and operators can also point the queries point at their own status service.

In this post, we want to inform you that the most recent snapshots of PowerDNS now include security polling, and we want to solicit your rapid feedback before this feature becomes part of the next PowerDNS releases.

Implementation

PowerDNS software periodically tries to resolve ‘auth-x.y.z.security-status.secpoll.powerdns.com|TXT’ or ‘recursor-x.y.z.security-status.secpoll.powerdns.com|TXT’ (if the security-poll-suffix setting is left at the default of secpoll.powerdns.com). No other data is included in the request.

The data returned is in one of the following forms:

  • NXDOMAIN or resolution failure
  • “1 Ok” -> security-status=1
  • “2 Upgrade recommended for security reasons, see http://powerdns.com/..” -> security-status=2
  • “3 Upgrade mandatory for security reasons, see http://powerdns.com/..” -> security-status=3

In cases 2 or 3, periodic logging commences at syslog level ‘Error’. The metric security-status is set to 2 or 3 respectively. The security status could be lowered however if we discover the issue is less urgent than we thought.

If resolution fails, and the previous security-status was 1, the new security-status becomes 0 (‘no data’). If the security-status was higher than 1, it will remain that way, and not get set to 0. In this way, security-status of 0 really means ‘no data’, and can not mask a known problem.

Distributions

Distributions frequently backport security fixes to the PowerDNS versions they ship. This might lead to a version number that is known to us to be insecure to be secure in reality.

To solve this issue, PowerDNS can be compiled with a distribution setting which will move the security polls from: ‘auth-x.y.z.security-status.secpoll.powerdns.com’ to ‘auth-x.y.z-n.debian.security-status.secpoll.powerdns.com

Note two things, one, there is a separate namespace for debian, and secondly, we use the package version of this release. This allows us to know that 3.6.0-1 (say) is insecure, but that 3.6.0-2 is not.

Details and how to disable

The configuration setting ‘security-poll-suffix’ is by default set to ‘secpoll.powerdns.com’. If empty, nothing is polled. This can be moved to ‘secpoll.yourorganization.com’. Our up to date secpoll zonefile is available on github for this purpose.

If compiled with PACKAGEVERSION=3.1.6-abcde.debian, queries will be sent to “auth-3.1.6-abcde.debian.security-status.security-poll-suffix”.

Delegation

If a distribution wants to host its own file with version information, we can delegate dist.security-status.secpoll.powerdns.com to their nameservers directly.

PowerDNS Authoritative Server 3.4.0 released

[Warning] Warning
Version 3.4.0 of the PowerDNS Authoritative Server is a major upgrade if you are coming from 2.9.x. Additionally, if you are coming from any 3.x version (including 3.3.1), there is a mandatory SQL schema upgrade. Please refer to Section 6, “From PowerDNS Authoritative Server 3.3.1 to 3.4.0” and any relevant sections before it, before deploying this version.
[Note] Note
Released September 30th, 2014

Find the downloads on our download page.

This is a performance, feature, bugfix and conformity update to 3.3.1 and any earlier version. It contains a huge amount of work by various contributors, to whom we are very grateful.

A list of changes since 3.3.1 follows.

Changes between RC2 and 3.4.0:

Changes between RC1 and RC2:

Changes between 3.3.1 and 3.4.0-RC1 follow.

DNSSEC changes:

  • commit bba8413: add option (max-signature-cache-entries) to limit the maximum number of cached signatures.
  • commit 28b66a9: limit the number of NSEC3 iterations (see RFC5155 10.3), with the max-nsec3-iterations option.
  • commit b50efd6: drop the ‘superfluous NSEC3′ option that old BIND validators need.
  • The bindbackend ‘hybrid’ mode was reintroduced by Kees Monshouwer. Enable it with bind-hybrid.
  • Aki Tuomi contributed experimental PKCS#11 support for DNSSEC key management with a (Soft)HSM.
  • Direct RRSIG queries now return NOTIMP.
  • commit fa37777: add secure-all-zones command to pdnssec
  • Unrectified zones can now get rectified ‘on the fly’ during outgoing AXFR. This makes it possible to run a hidden signing master without rectification.
  • commit 82fb538: AXFR in: don’t accept zones with a mixture of Opt-Out NSEC3 RRs and non-Opt-Out NSEC3 RRs
  • Various minor bugfixes, mostly from the unstoppable Kees Monshouwer.
  • commit 0c4c552: set non-zero exit status in pdnssec if an exception was thrown, for easier automatic usage.
  • commit b8bd119: pdnssec -v show-zone: Print all keys instead of just entry point keys.
  • commit 52e0d78: answer direct NSEC queries without DO bit
  • commit ca2eb01: output ZSK DNSKEY records if experimental-direct-dnskey support is enabled
  • commit 83609e2: SOA-EDIT: fix INCEPTION-INCREMENT handling
  • commit ac4a2f1: AXFR-out can handle secure and insecure NSEC3 optout delegations
  • commit ff47302: AXFR-in can handle secure and insecure NSEC3 optout delegations

New features:

  • DNAME support. Enable with experimental-dname-processing.
  • PowerDNS can now send stats directly to Carbon servers. Enable with carbon-server, tweak with carbon-ourname and carbon-interval.
  • commit 767da1a: Add list-zone capability to pdns_control
  • commit 51f6bca: Add delete-zone to pdnssec.
  • The gsql backends now support record comments, and disabling records.
  • The new reuseport config option allows setting SO_REUSEPORT, which allows for some performance improvements.
  • local-address-nonexist-fail and local-ipv6-nonexist-fail allow pdns to start up even if some addresses fail to bind.
  • ‘AXFR-SOURCE’ in domainmetadata sets the source address for an AXFR retrieval.
  • commit 451ba51: Implement pdnssec get-meta/set-meta
  • Experimental RFC2136/DNS UPDATE support from Ruben d’Arco, with extensive testing by Kees Monshouwer.
  • pdns_control bind-add-zone
  • New option bind-ignore-broken-records ignores out-of-zone records while loading zone files.
  • pdnssec now has commands for TSIG key management.
  • We now support other algorithms than MD5 for TSIG.
  • commit ba7244a: implement pdns_control qtypes
  • Support for += syntax for options

Bugfixes:

  • We verify the algorithm used for TSIG queries, and use the right algorithm in signing if there is possible confusion. Plus a few minor TSIG-related fixes.
  • commit ff99a74: making *-threads settings empty now yields a default of one instead of zero.
  • commit 9215e60: we had a deadly embrace in getUpdatedMasters in bindbackend reimplementation, thanks to Winfried for detailed debugging!
  • commit 9245fd9: don’t addSuckRequest after supermaster zone creation to avoid one cause of simultaneous AXFR for the same zone
  • commit 719f902: fix dual-stack superslave when multiple namservers share a ip
  • commit 33966bf: avoid address truncation in doNotifications
  • commit eac85b1: prevent duplicate slave notications caused by different ipv6 address formatting
  • commit 3c8a711: make notification queue ipv6 compatible
  • commit 0c13e45: make isMaster ip check more tolerant for different ipv6 notations
  • Various fixes for possible issues reported by Coverity Scan (commit f17c93b, )
  • commit 9083987: don’t rely on included polarssl header files when using system polarssl. Spotted by Oden Eriksson of Mandriva, thanks!
  • Various users reported pdns_control hangs, especially when using the guardian. We are confident that all causes of these hangs are now gone.
  • Decreasing the webserver ringbuffer size could cause crashes.
  • commit 4c89cce: nproxy: Add missing chdir(“/”) after chroot()
  • commit 016a0ab: actually notice timeout during AXFR retrieve, thanks hkraal

REST API changes:

  • The REST API was much improved and is nearing stability, thanks to Christian Hofstaedtler and others.
  • Mark Schouten at Tuxis contributed a zone importer.

Other changes:

  • Our tarballs and packages now include *.sql schema files for the SQL backends.
  • The webserver (including API) now has an ACL (webserver-allow-from).
  • Webserver (including API) is now powered by YaHTTP.
  • Various autotools usage improvements from Ruben Kerkhof.
  • The dist tarball is now bzip2-compressed instead of gzip.
  • Various remotebackend updates, including replacing curl with (included) yahttp.
  • Dynamic module loading is now allowed on Mac OS X.
  • The AXFR ACL (allow-axfr-ips) now defaults to 127.0.0.0/8,::1 instead of the whole world.
  • commit ba91c2f: remove unused gpgsql-socket option and document postgres socket usage
  • Improved support for Lua 5.2.
  • The edns-subnet option code is now fixed at 8, and the edns-subnet-option-numbers option has been removed.
  • geobackend now has very limited edns-subnet support – it will use the ‘real’ remote if available.
  • pipebackend ABI v4 adds the zone name to the AXFR command.
  • We now avoid getaddrinfo() as much as possible.
  • The packet cache now handles (forwarded) recursive answers better, including TTL aging and respecting allow-recursion.
  • commit ff5ba4f: pdns_server –help no longer exits with 1.
  • Mark Zealey contributed an experimental LMDB backend. Kees Monshouwer added experimental DNSSEC support to it. Thanks, both!
  • commit 81859ba: No longer attempt to answer questions coming in from port 0, reply would not reach them anyhow. Thanks to Niels Bakker and sid3windr for insight & debugging. Closes ticket 844.
  • RCodes are now reported in text in various places, thanks Aki.
  • Kees Monshouwer set up automatic testing for the oracle and goracle backends, and fixed various issues in them.
  • Leftovers of previous support for Windows have been removed, thanks to Kees Monshouwer, Aki Tuomi.
  • Bundled PolarSSL has been upgraded to 1.3.2
  • PolarSSL replaced previously bundled implementations of AES (commit e22d9b4) and SHA (commit 9101035)
  • bindbackend is now a module
  • commit 14a2e52: Use the inet data type for supermasters.ip on postgrsql.
  • We now send an empty SERVFAIL when a CNAME chain is too long, instead of including the partial chain.
  • commit 3613a51: Show built-in features in –version output
  • commit 4bd7d35: make domainmetadata queries case insensitive
  • commit 088c334: output warning message when no to be notified NS’s are found
  • commit 5631b44: gpsqlbackend: use empty defaults for dbname and user; libpq will use the current user name for both by default
  • commit d87ded3: implement udp-truncation-threshold to override the previous 1680 byte maximum response datagram size – no matter what EDNS0 said. Plus document it.
  • Implement udp-truncation-threshold to override the previous 1680 byte maximum response datagram size – no matter what EDNS0 said.
  • On shutdown, PowerDNS now attempts to stop all processes in its process group, especially useful for pipe/remotebackend users. Feature donated by Spotify.
  • Removed settings related to fancy records, as we haven’t supported those since version 3.0
  • Based on earlier work by Mark Zealey, Kees Monshouwer increased our packet cache performance between 200% and 500% depending on the situation, by simplifying some code in commit 801812e and commit 8403ade.

Authoritative Server 3.4.0 Release Candidate 2

[Warning] Warning
Version 3.4.0 of the PowerDNS Authoritative Server is a major upgrade if you are coming from 2.9.x. Additionally, if you are coming from any 3.x version (including 3.3.1), there is a mandatory SQL schema upgrade. Please refer toSection 6, “From PowerDNS Authoritative Server 3.3.1 to 3.4.0” and any relevant sections before it, before deploying this version.

This is a performance, feature, bugfix and conformity update to 3.3.1 and any earlier version. It contains a huge amount of work by various contributors, to whom we are very grateful.

A list of changes since 3.3.1 follows.

Changes between RC1 and RC2:

Security Update: PowerDNS Recursor 3.6.1

Hi everybody,

We regret that we have to announce a PowerDNS Recursor security release:

Issue:    A specific sequence of packets can crash PowerDNS Recursor 3.6.0 remotely
CVE:      CVE-2014-3614
Affected: All deployments of PowerDNS Recursor 3.6.0 
Not Affected: 
          PowerDNS Authoritative Server, PowerDNS Recursor versions other than 3.6.0 
Workaround: 
          1) Only users from netmasks specified in 'allow-from' can cause the crash 
          2) add automated restarting
Remediation: 
          Upgrade to 3.6.1, or apply our minimal patch and recompile
          Distributions shipping 3.6.0 have been notified and will be providing updates very soon

Recently, we’ve discovered that PowerDNS Recursor 3.6.0 (but NOT earlier) can crash when exposed to a specific sequence of malformed packets. This sequence happened spontaneously with one of our largest deployments, and the packets did not appear to have a malicious origin.

Yet, this crash can be triggered remotely, leading to a denial of service attack. There appears to be no way to use this crash for system compromise or stack overflow.

PowerDNS Recursor 3.6.1 packages and sources are available from https://www.powerdns.com/downloads.html

In addition, if you want to apply a minimal fix, it can be found on: https://xs.powerdns.com/tmp/minipatch-3.6.1

Finally, distributions that ship PowerDNS Recursor 3.6.0 have been notified and will be providing updated packages soon.

As for workarounds, only clients in allow-from are able to trigger the crash, so this should be limited to your userbase. Secondly, https://github.com/PowerDNS/pdns/blob/master/contrib/upstart-recursor.conf
and https://github.com/PowerDNS/pdns/blob/master/contrib/systemd-pdns-recursor.service
can be used to enable Upstart and Systemd to restart the PowerDNS Recursor in case of a crash.

3.6.1 release notes:

In addition to various fixes related to this potential crash, 3.6.1 fixes a few minor issues and adds a debugging feature:

  • We could not encode IPv6 AAAA records that mapped to IPv4 addresses in some cases (:ffff.1.2.3.4). Fixed in commit c90fcbd , closing ticket 1663.
  • Improve systemd startup timing with respect to network availability (commit cf86c6a), thanks to Morten Stevens.
  • Realtime telemetry can now be enabled at runtime, for example with ‘rec_control carbon-server 82.94.213.34 ourname1234′. This ties in to our existing carbon-server and carbon-ourname settings, but now at runtime. This specific invocation will make your stats appear automatically on our public telemetry server.

We want to thank the dedicated PowerDNS users that spent months investigating the rare crashes they observed. Without such an engaged community, we would never be able to chase down issues like these.

If you need any help with upgrading, please contact us either on the mailing lists or via our website or phone.

Problems posting to our mailing lists

Hi everybody,

Over the past few months, we’d been receiving some reports of people having problems posting to our lists. At first, it appeared the problem was caused by subscribers emailing to the wrong list address. We have told a few of you that it was your fault.

It turns out that even though we know a thing or two about DNS, we managed to mess up our own. ‘mailman.powerdns.com’ was a CNAME. This in turn led some mail transfer agent software to rewrite posts to pdns-users at mailman.powerdns.com to pdns-users at xs.powerdns.com, and this would then fail within mailman.

We want to apologize for 1) causing this mess and 2) blaming our users for it. Sorry.

Thanks to Leo, Winfried and Ruben for nagging us about the issue. You were right.

The situation has now been resolved, and you should no longer have problems posting to our lists.

Bert