xref: /freebsd-10-stable/contrib/ntp/NEWS

---
NTP 4.2.8p3 (Harlan Stenn <stenn@ntp.org>, 2015/06/29) 

Focus: 1 Security fix.  Bug fixes and enhancements.  Leap-second improvements.

Severity: MEDIUM

Security Fix:

* [Sec 2853] Crafted remote config packet can crash some versions of
  ntpd.  Aleksis Kauppinen, Juergen Perlinger, Harlan Stenn.

Under specific circumstances an attacker can send a crafted packet to
cause a vulnerable ntpd instance to crash. This requires each of the
following to be true:

1) ntpd set up to allow remote configuration (not allowed by default), and
2) knowledge of the configuration password, and
3) access to a computer entrusted to perform remote configuration. 

This vulnerability is considered low-risk.

New features in this release:

Optional (disabled by default) support to have ntpd provide smeared
leap second time.  A specially built and configured ntpd will only
offer smeared time in response to client packets.  These response
packets will also contain a "refid" of 254.a.b.c, where the 24 bits
of a, b, and c encode the amount of smear in a 2:22 integer:fraction 
format.  See README.leapsmear and http://bugs.ntp.org/2855 for more
information.

   *IF YOU CHOOSE TO CONFIGURE NTPD TO PROVIDE LEAP SMEAR TIME*
   *BE SURE YOU DO NOT OFFER THAT TIME ON PUBLIC TIMESERVERS.*

We've imported the Unity test framework, and have begun converting
the existing google-test items to this new framework.  If you want
to write new tests or change old ones, you'll need to have ruby
installed.  You don't need ruby to run the test suite.

Bug Fixes and Improvements:

* CID 739725: Fix a rare resource leak in libevent/listener.c.
* CID 1295478: Quiet a pedantic potential error from the fix for Bug 2776.
* CID 1296235: Fix refclock_jjy.c and correcting type of the driver40-ja.html
* CID 1269537: Clean up a line of dead code in getShmTime().
* [Bug 1060] Buffer overruns in libparse/clk_rawdcf.c.  Helge Oldach.
* [Bug 2590] autogen-5.18.5.
* [Bug 2612] restrict: Warn when 'monitor' can't be disabled because
  of 'limited'.
* [Bug 2650] fix includefile processing.
* [Bug 2745] ntpd -x steps clock on leap second
   Fixed an initial-value problem that caused misbehaviour in absence of
   any leapsecond information.
   Do leap second stepping only of the step adjustment is beyond the
   proper jump distance limit and step correction is allowed at all.
* [Bug 2750] build for Win64
  Building for 32bit of loopback ppsapi needs def file
* [Bug 2776] Improve ntpq's 'help keytype'.
* [Bug 2778] Implement "apeers"  ntpq command to include associd.
* [Bug 2782] Refactor refclock_shm.c, add memory barrier protection.
* [Bug 2792] If the IFF_RUNNING interface flag is supported then an
  interface is ignored as long as this flag is not set since the
  interface is not usable (e.g., no link).
* [Bug 2794] Clean up kernel clock status reports.
* [Bug 2800] refclock_true.c true_debug() can't open debug log because
  of incompatible open/fdopen parameters.
* [Bug 2804] install-local-data assumes GNU 'find' semantics.
* [Bug 2805] ntpd fails to join multicast group.
* [Bug 2806] refclock_jjy.c supports the Telephone JJY.
* [Bug 2808] GPSD_JSON driver enhancements, step 1.
  Fix crash during cleanup if GPS device not present and char device.
  Increase internal token buffer to parse all JSON data, even SKY.
  Defer logging of errors during driver init until the first unit is
  started, so the syslog is not cluttered when the driver is not used.
  Various improvements, see http://bugs.ntp.org/2808 for details.
  Changed libjsmn to a more recent version.
* [Bug 2810] refclock_shm.c memory barrier code needs tweaks for QNX.
* [Bug 2813] HP-UX needs -D__STDC_VERSION__=199901L and limits.h.
* [Bug 2815] net-snmp before v5.4 has circular library dependencies.
* [Bug 2821] Add a missing NTP_PRINTF and a missing const.
* [Bug 2822] New leap column in sntp broke NTP::Util.pm.
* [Bug 2824] Convert update-leap to perl. (also see 2769)
* [Bug 2825] Quiet file installation in html/ .
* [Bug 2830] ntpd doesn't always transfer the correct TAI offset via autokey
   NTPD transfers the current TAI (instead of an announcement) now.
   This might still needed improvement.
   Update autokey data ASAP when 'sys_tai' changes.
   Fix unit test that was broken by changes for autokey update.
   Avoid potential signature length issue and use DPRINTF where possible
     in ntp_crypto.c.
* [Bug 2832] refclock_jjy.c supports the TDC-300.
* [Bug 2834] Correct a broken html tag in html/refclock.html
* [Bug 2836] DFC77 patches from Frank Kardel to make decoding more
  robust, and require 2 consecutive timestamps to be consistent.
* [Bug 2837] Allow a configurable DSCP value.
* [Bug 2837] add test for DSCP to ntpd/complete.conf.in
* [Bug 2842] Glitch in ntp.conf.def documentation stanza.
* [Bug 2842] Bug in mdoc2man.
* [Bug 2843] make check fails on 4.3.36
   Fixed compiler warnings about numeric range overflow
   (The original topic was fixed in a byplay to bug#2830)
* [Bug 2845] Harden memory allocation in ntpd.
* [Bug 2852] 'make check' can't find unity.h.  Hal Murray.
* [Bug 2854] Missing brace in libntp/strdup.c.  Masanari Iida.
* [Bug 2855] Parser fix for conditional leap smear code.  Harlan Stenn.
* [Bug 2855] Report leap smear in the REFID.  Harlan Stenn.
* [Bug 2855] Implement conditional leap smear code.  Martin Burnicki.
* [Bug 2856] ntpd should wait() on terminated child processes.  Paul Green.
* [Bug 2857] Stratus VOS does not support SIGIO.  Paul Green.
* [Bug 2859] Improve raw DCF77 robustness deconding.  Frank Kardel.
* [Bug 2860] ntpq ifstats sanity check is too stringent.  Frank Kardel.
* html/drivers/driver22.html: typo fix.  Harlan Stenn.
* refidsmear test cleanup.  Tomasz Flendrich.
* refidsmear function support and tests.  Harlan Stenn.
* sntp/tests/Makefile.am: remove g_nameresolution.cpp as it tested
  something that was only in the 4.2.6 sntp.  Harlan Stenn.
* Modified tests/bug-2803/Makefile.am so it builds Unity framework tests.
  Damir Tomi��
* Modified tests/libtnp/Makefile.am so it builds Unity framework tests.
  Damir Tomi��
* Modified sntp/tests/Makefile.am so it builds Unity framework tests.
  Damir Tomi��
* tests/sandbox/smeartest.c: Harlan Stenn, Damir Tomic, Juergen Perlinger.
* Converted from gtest to Unity: tests/bug-2803/. Damir Tomi��
* Converted from gtest to Unity: tests/libntp/ a_md5encrypt, atoint.c,
  atouint.c, authkeys.c, buftvtots.c, calendar.c, caljulian.c,
  calyearstart.c, clocktime.c, hextoint.c, lfpfunc.c, modetoa.c,
  numtoa.c, numtohost.c, refnumtoa.c, ssl_init.c, statestr.c,
  timespecops.c, timevalops.c, uglydate.c, vi64ops.c, ymd2yd.c.
  Damir Tomi��
* Converted from gtest to Unity: sntp/tests/ kodDatabase.c, kodFile.c,
  networking.c, keyFile.c, utilities.cpp, sntptest.h,
  fileHandlingTest.h. Damir Tomi��
* Initial support for experimental leap smear code.  Harlan Stenn.
* Fixes to sntp/tests/fileHandlingTest.h.in.  Harlan Stenn.
* Report select() debug messages at debug level 3 now.
* sntp/scripts/genLocInfo: treat raspbian as debian.
* Unity test framework fixes.
  ** Requires ruby for changes to tests.
* Initial support for PACKAGE_VERSION tests.
* sntp/libpkgver belongs in EXTRA_DIST, not DIST_SUBDIRS.
* tests/bug-2803/Makefile.am must distribute bug-2803.h.
* Add an assert to the ntpq ifstats code.
* Clean up the RLIMIT_STACK code.
* Improve the ntpq documentation around the controlkey keyid.
* ntpq.c cleanup.
* Windows port build cleanup.

---
NTP 4.2.8p2 (Harlan Stenn <stenn@ntp.org>, 2015/04/07) 

Focus: Security and Bug fixes, enhancements.

Severity: MEDIUM
 
In addition to bug fixes and enhancements, this release fixes the
following medium-severity vulnerabilities involving private key
authentication:

* [Sec 2779] ntpd accepts unauthenticated packets with symmetric key crypto.

    References: Sec 2779 / CVE-2015-1798 / VU#374268
    Affects: All NTP4 releases starting with ntp-4.2.5p99 up to but not
	including ntp-4.2.8p2 where the installation uses symmetric keys
	to authenticate remote associations.
    CVSS: (AV:A/AC:M/Au:N/C:P/I:P/A:P) Base Score: 5.4
    Date Resolved: Stable (4.2.8p2) 07 Apr 2015
    Summary: When ntpd is configured to use a symmetric key to authenticate
	a remote NTP server/peer, it checks if the NTP message
	authentication code (MAC) in received packets is valid, but not if
	there actually is any MAC included. Packets without a MAC are
	accepted as if they had a valid MAC. This allows a MITM attacker to
	send false packets that are accepted by the client/peer without
	having to know the symmetric key. The attacker needs to know the
	transmit timestamp of the client to match it in the forged reply
	and the false reply needs to reach the client before the genuine
	reply from the server. The attacker doesn't necessarily need to be
	relaying the packets between the client and the server.

	Authentication using autokey doesn't have this problem as there is
	a check that requires the key ID to be larger than NTP_MAXKEY,
	which fails for packets without a MAC.
    Mitigation:
        Upgrade to 4.2.8p2, or later, from the NTP Project Download Page
	or the NTP Public Services Project Download Page
        Configure ntpd with enough time sources and monitor it properly. 
    Credit: This issue was discovered by Miroslav Lichvar, of Red Hat. 

* [Sec 2781] Authentication doesn't protect symmetric associations against
  DoS attacks.

    References: Sec 2781 / CVE-2015-1799 / VU#374268
    Affects: All NTP releases starting with at least xntp3.3wy up to but
	not including ntp-4.2.8p2 where the installation uses symmetric
	key authentication.
    CVSS: (AV:A/AC:M/Au:N/C:P/I:P/A:P) Base Score: 5.4
    Note: the CVSS base Score for this issue could be 4.3 or lower, and
	it could be higher than 5.4.
    Date Resolved: Stable (4.2.8p2) 07 Apr 2015
    Summary: An attacker knowing that NTP hosts A and B are peering with
	each other (symmetric association) can send a packet to host A
	with source address of B which will set the NTP state variables
	on A to the values sent by the attacker. Host A will then send
	on its next poll to B a packet with originate timestamp that
	doesn't match the transmit timestamp of B and the packet will
	be dropped. If the attacker does this periodically for both
	hosts, they won't be able to synchronize to each other. This is
	a known denial-of-service attack, described at
	https://www.eecis.udel.edu/~mills/onwire.html .

	According to the document the NTP authentication is supposed to
	protect symmetric associations against this attack, but that
	doesn't seem to be the case. The state variables are updated even
	when authentication fails and the peers are sending packets with
	originate timestamps that don't match the transmit timestamps on
	the receiving side.

	This seems to be a very old problem, dating back to at least
	xntp3.3wy. It's also in the NTPv3 (RFC 1305) and NTPv4 (RFC 5905)
	specifications, so other NTP implementations with support for
	symmetric associations and authentication may be vulnerable too.
	An update to the NTP RFC to correct this error is in-process.
    Mitigation:
        Upgrade to 4.2.8p2, or later, from the NTP Project Download Page
	or the NTP Public Services Project Download Page
        Note that for users of autokey, this specific style of MITM attack
	is simply a long-known potential problem.
        Configure ntpd with appropriate time sources and monitor ntpd.
	Alert your staff if problems are detected. 
    Credit: This issue was discovered by Miroslav Lichvar, of Red Hat. 

* New script: update-leap
The update-leap script will verify and if necessary, update the
leap-second definition file.
It requires the following commands in order to work:

	wget logger tr sed shasum

Some may choose to run this from cron.  It needs more portability testing.

Bug Fixes and Improvements:

* [Bug 1787] DCF77's formerly "antenna" bit is "call bit" since 2003.
* [Bug 1960] setsockopt IPV6_MULTICAST_IF: Invalid argument.
* [Bug 2346] "graceful termination" signals do not do peer cleanup.
* [Bug 2728] See if C99-style structure initialization works.
* [Bug 2747] Upgrade libevent to 2.1.5-beta.
* [Bug 2749] ntp/lib/NTP/Util.pm needs update for ntpq -w, IPv6, .POOL. .
* [Bug 2751] jitter.h has stale copies of l_fp macros.
* [Bug 2756] ntpd hangs in startup with gcc 3.3.5 on ARM.
* [Bug 2757] Quiet compiler warnings.
* [Bug 2759] Expose nonvolatile/clk_wander_threshold to ntpq.
* [Bug 2763] Allow different thresholds for forward and backward steps.
* [Bug 2766] ntp-keygen output files should not be world-readable.
* [Bug 2767] ntp-keygen -M should symlink to ntp.keys.
* [Bug 2771] nonvolatile value is documented in wrong units.
* [Bug 2773] Early leap announcement from Palisade/Thunderbolt
* [Bug 2774] Unreasonably verbose printout - leap pending/warning
* [Bug 2775] ntp-keygen.c fails to compile under Windows.
* [Bug 2777] Fixed loops and decoding of Meinberg GPS satellite info.
  Removed non-ASCII characters from some copyright comments.
  Removed trailing whitespace.
  Updated definitions for Meinberg clocks from current Meinberg header files.
  Now use C99 fixed-width types and avoid non-ASCII characters in comments.
  Account for updated definitions pulled from Meinberg header files.
  Updated comments on Meinberg GPS receivers which are not only called GPS16x.
  Replaced some constant numbers by defines from ntp_calendar.h
  Modified creation of parse-specific variables for Meinberg devices
  in gps16x_message().
  Reworked mk_utcinfo() to avoid printing of ambiguous leap second dates.
  Modified mbg_tm_str() which now expexts an additional parameter controlling
  if the time status shall be printed.
* [Sec 2779] ntpd accepts unauthenticated packets with symmetric key crypto.
* [Sec 2781] Authentication doesn't protect symmetric associations against
  DoS attacks.
* [Bug 2783] Quiet autoconf warnings about missing AC_LANG_SOURCE.
* [Bug 2789] Quiet compiler warnings from libevent.
* [Bug 2790] If ntpd sets the Windows MM timer highest resolution
  pause briefly before measuring system clock precision to yield
  correct results.
* Comment from Juergen Perlinger in ntp_calendar.c to make the code clearer.
* Use predefined function types for parse driver functions
  used to set up function pointers.
  Account for changed prototype of parse_inp_fnc_t functions.
  Cast parse conversion results to appropriate types to avoid
  compiler warnings.
  Let ioctl() for Windows accept a (void *) to avoid compiler warnings
  when called with pointers to different types.

---
NTP 4.2.8p1 (Harlan Stenn <stenn@ntp.org>, 2015/02/04) 

Focus: Security and Bug fixes, enhancements.

Severity: HIGH
 
In addition to bug fixes and enhancements, this release fixes the
following high-severity vulnerabilities:

* vallen is not validated in several places in ntp_crypto.c, leading
  to a potential information leak or possibly a crash

    References: Sec 2671 / CVE-2014-9297 / VU#852879
    Affects: All NTP4 releases before 4.2.8p1 that are running autokey.
    CVSS: (AV:N/AC:L/Au:N/C:P/I:P/A:P) Base Score: 7.5
    Date Resolved: Stable (4.2.8p1) 04 Feb 2015
    Summary: The vallen packet value is not validated in several code
             paths in ntp_crypto.c which can lead to information leakage
	     or perhaps a crash of the ntpd process.
    Mitigation - any of:
	Upgrade to 4.2.8p1, or later, from the NTP Project Download Page
		or the NTP Public Services Project Download Page.
	Disable Autokey Authentication by removing, or commenting out,
		all configuration directives beginning with the "crypto"
		keyword in your ntp.conf file. 
    Credit: This vulnerability was discovered by Stephen Roettger of the
    	Google Security Team, with additional cases found by Sebastian
	Krahmer of the SUSE Security Team and Harlan Stenn of Network
	Time Foundation. 

* ::1 can be spoofed on some OSes, so ACLs based on IPv6 ::1 addresses
  can be bypassed.

    References: Sec 2672 / CVE-2014-9298 / VU#852879
    Affects: All NTP4 releases before 4.2.8p1, under at least some
	versions of MacOS and Linux. *BSD has not been seen to be vulnerable.
    CVSS: (AV:N/AC:L/Au:N/C:P/I:P/A:C) Base Score: 9
    Date Resolved: Stable (4.2.8p1) 04 Feb 2014
    Summary: While available kernels will prevent 127.0.0.1 addresses
	from "appearing" on non-localhost IPv4 interfaces, some kernels
	do not offer the same protection for ::1 source addresses on
	IPv6 interfaces. Since NTP's access control is based on source
	address and localhost addresses generally have no restrictions,
	an attacker can send malicious control and configuration packets
	by spoofing ::1 addresses from the outside. Note Well: This is
	not really a bug in NTP, it's a problem with some OSes. If you
	have one of these OSes where ::1 can be spoofed, ALL ::1 -based
	ACL restrictions on any application can be bypassed!
    Mitigation:
        Upgrade to 4.2.8p1, or later, from the NTP Project Download Page
	or the NTP Public Services Project Download Page
        Install firewall rules to block packets claiming to come from
	::1 from inappropriate network interfaces. 
    Credit: This vulnerability was discovered by Stephen Roettger of
	the Google Security Team. 

Additionally, over 30 bugfixes and improvements were made to the codebase.
See the ChangeLog for more information.

---
NTP 4.2.8 (Harlan Stenn <stenn@ntp.org>, 2014/12/18) 
 
Focus: Security and Bug fixes, enhancements.
 
Severity: HIGH
 
In addition to bug fixes and enhancements, this release fixes the
following high-severity vulnerabilities:

************************** vv NOTE WELL vv *****************************

The vulnerabilities listed below can be significantly mitigated by
following the BCP of putting

 restrict default ... noquery

in the ntp.conf file.  With the exception of:

   receive(): missing return on error
   References: Sec 2670 / CVE-2014-9296 / VU#852879

below (which is a limited-risk vulnerability), none of the recent
vulnerabilities listed below can be exploited if the source IP is
restricted from sending a 'query'-class packet by your ntp.conf file.

************************** ^^ NOTE WELL ^^ *****************************

* Weak default key in config_auth().

  References: [Sec 2665] / CVE-2014-9293 / VU#852879
  CVSS: (AV:N/AC:L/Au:M/C:P/I:P/A:C) Base Score: 7.3
  Vulnerable Versions: all releases prior to 4.2.7p11
  Date Resolved: 28 Jan 2010

  Summary: If no 'auth' key is set in the configuration file, ntpd
	would generate a random key on the fly.  There were two
	problems with this: 1) the generated key was 31 bits in size,
	and 2) it used the (now weak) ntp_random() function, which was
	seeded with a 32-bit value and could only provide 32 bits of
	entropy.  This was sufficient back in the late 1990s when the
	code was written.  Not today.

  Mitigation - any of:
	- Upgrade to 4.2.7p11 or later.
	- Follow BCP and put 'restrict ... noquery' in your ntp.conf file.

  Credit: This vulnerability was noticed in ntp-4.2.6 by Neel Mehta
  	of the Google Security Team.

* Non-cryptographic random number generator with weak seed used by
  ntp-keygen to generate symmetric keys.

  References: [Sec 2666] / CVE-2014-9294 / VU#852879
  CVSS: (AV:N/AC:L/Au:M/C:P/I:P/A:C) Base Score: 7.3
  Vulnerable Versions: All NTP4 releases before 4.2.7p230
  Date Resolved: Dev (4.2.7p230) 01 Nov 2011

  Summary: Prior to ntp-4.2.7p230 ntp-keygen used a weak seed to
  	prepare a random number generator that was of good quality back
	in the late 1990s. The random numbers produced was then used to
	generate symmetric keys. In ntp-4.2.8 we use a current-technology
	cryptographic random number generator, either RAND_bytes from
	OpenSSL, or arc4random(). 

  Mitigation - any of:
  	- Upgrade to 4.2.7p230 or later.
	- Follow BCP and put 'restrict ... noquery' in your ntp.conf file.

  Credit:  This vulnerability was discovered in ntp-4.2.6 by
  	Stephen Roettger of the Google Security Team.

* Buffer overflow in crypto_recv()

  References: Sec 2667 / CVE-2014-9295 / VU#852879
  CVSS: (AV:N/AC:L/Au:N/C:P/I:P/A:P) Base Score: 7.5
  Versions: All releases before 4.2.8
  Date Resolved: Stable (4.2.8) 18 Dec 2014

  Summary: When Autokey Authentication is enabled (i.e. the ntp.conf
  	file contains a 'crypto pw ...' directive) a remote attacker
	can send a carefully crafted packet that can overflow a stack
	buffer and potentially allow malicious code to be executed
	with the privilege level of the ntpd process.

  Mitigation - any of:
  	- Upgrade to 4.2.8, or later, or
	- Disable Autokey Authentication by removing, or commenting out,
	  all configuration directives beginning with the crypto keyword
	  in your ntp.conf file. 

  Credit: This vulnerability was discovered by Stephen Roettger of the
  	Google Security Team. 

* Buffer overflow in ctl_putdata()

  References: Sec 2668 / CVE-2014-9295 / VU#852879
  CVSS: (AV:N/AC:L/Au:N/C:P/I:P/A:P) Base Score: 7.5
  Versions: All NTP4 releases before 4.2.8
  Date Resolved: Stable (4.2.8) 18 Dec 2014

  Summary: A remote attacker can send a carefully crafted packet that
  	can overflow a stack buffer and potentially allow malicious
	code to be executed with the privilege level of the ntpd process.

  Mitigation - any of:
  	- Upgrade to 4.2.8, or later.
	- Follow BCP and put 'restrict ... noquery' in your ntp.conf file.

  Credit: This vulnerability was discovered by Stephen Roettger of the
  	Google Security Team. 

* Buffer overflow in configure()

  References: Sec 2669 / CVE-2014-9295 / VU#852879
  CVSS: (AV:N/AC:L/Au:N/C:P/I:P/A:P) Base Score: 7.5
  Versions: All NTP4 releases before 4.2.8
  Date Resolved: Stable (4.2.8) 18 Dec 2014

  Summary: A remote attacker can send a carefully crafted packet that
	can overflow a stack buffer and potentially allow malicious
	code to be executed with the privilege level of the ntpd process.

  Mitigation - any of:
  	- Upgrade to 4.2.8, or later.
	- Follow BCP and put 'restrict ... noquery' in your ntp.conf file.

  Credit: This vulnerability was discovered by Stephen Roettger of the
	Google Security Team. 

* receive(): missing return on error

  References: Sec 2670 / CVE-2014-9296 / VU#852879
  CVSS: (AV:N/AC:L/Au:N/C:N/I:N/A:P) Base Score: 5.0
  Versions: All NTP4 releases before 4.2.8
  Date Resolved: Stable (4.2.8) 18 Dec 2014

  Summary: Code in ntp_proto.c:receive() was missing a 'return;' in
  	the code path where an error was detected, which meant
	processing did not stop when a specific rare error occurred.
	We haven't found a way for this bug to affect system integrity.
	If there is no way to affect system integrity the base CVSS
	score for this bug is 0. If there is one avenue through which
	system integrity can be partially affected, the base score
	becomes a 5. If system integrity can be partially affected
	via all three integrity metrics, the CVSS base score become 7.5.

  Mitigation - any of:
        - Upgrade to 4.2.8, or later,
        - Remove or comment out all configuration directives
	  beginning with the crypto keyword in your ntp.conf file. 

  Credit: This vulnerability was discovered by Stephen Roettger of the
  	Google Security Team. 

See http://support.ntp.org/security for more information.

New features / changes in this release:

Important Changes

* Internal NTP Era counters

The internal counters that track the "era" (range of years) we are in
rolls over every 136 years'.  The current "era" started at the stroke of
midnight on 1 Jan 1900, and ends just before the stroke of midnight on
1 Jan 2036.
In the past, we have used the "midpoint" of the  range to decide which
era we were in.  Given the longevity of some products, it became clear
that it would be more functional to "look back" less, and "look forward"
more.  We now compile a timestamp into the ntpd executable and when we
get a timestamp we us the "built-on" to tell us what era we are in.
This check "looks back" 10 years, and "looks forward" 126 years.

* ntpdc responses disabled by default

Dave Hart writes:

For a long time, ntpq and its mostly text-based mode 6 (control) 
protocol have been preferred over ntpdc and its mode 7 (private 
request) protocol for runtime queries and configuration.  There has 
been a goal of deprecating ntpdc, previously held back by numerous 
capabilities exposed by ntpdc with no ntpq equivalent.  I have been 
adding commands to ntpq to cover these cases, and I believe I've 
covered them all, though I've not compared command-by-command 
recently. 

As I've said previously, the binary mode 7 protocol involves a lot of 
hand-rolled structure layout and byte-swapping code in both ntpd and 
ntpdc which is hard to get right.  As ntpd grows and changes, the 
changes are difficult to expose via ntpdc while maintaining forward 
and backward compatibility between ntpdc and ntpd.  In contrast, 
ntpq's text-based, label=value approach involves more code reuse and 
allows compatible changes without extra work in most cases. 

Mode 7 has always been defined as vendor/implementation-specific while 
mode 6 is described in RFC 1305 and intended to be open to interoperate 
with other implementations.  There is an early draft of an updated 
mode 6 description that likely will join the other NTPv4 RFCs 
eventually. (http://tools.ietf.org/html/draft-odonoghue-ntpv4-control-01)

For these reasons, ntpd 4.2.7p230 by default disables processing of 
ntpdc queries, reducing ntpd's attack surface and functionally 
deprecating ntpdc.  If you are in the habit of using ntpdc for certain 
operations, please try the ntpq equivalent.  If there's no equivalent, 
please open a bug report at http://bugs.ntp.org./

In addition to the above, over 1100 issues have been resolved between
the 4.2.6 branch and 4.2.8.  The ChangeLog file in the distribution
lists these.

--- 
NTP 4.2.6p5 (Harlan Stenn <stenn@ntp.org>, 2011/12/24) 
 
Focus: Bug fixes
 
Severity: Medium 
 
This is a recommended upgrade. 

This release updates sys_rootdisp and sys_jitter calculations to match the
RFC specification, fixes a potential IPv6 address matching error for the
"nic" and "interface" configuration directives, suppresses the creation of
extraneous ephemeral associations for certain broadcastclient and
multicastclient configurations, cleans up some ntpq display issues, and
includes improvements to orphan mode, minor bugs fixes and code clean-ups.

New features / changes in this release:

ntpd

 * Updated "nic" and "interface" IPv6 address handling to prevent 
   mismatches with localhost [::1] and wildcard [::] which resulted from
   using the address/prefix format (e.g. fe80::/64)
 * Fix orphan mode stratum incorrectly counting to infinity
 * Orphan parent selection metric updated to includes missing ntohl()
 * Non-printable stratum 16 refid no longer sent to ntp
 * Duplicate ephemeral associations suppressed for broadcastclient and
   multicastclient without broadcastdelay
 * Exclude undetermined sys_refid from use in loopback TEST12
 * Exclude MODE_SERVER responses from KoD rate limiting
 * Include root delay in clock_update() sys_rootdisp calculations
 * get_systime() updated to exclude sys_residual offset (which only
   affected bits "below" sys_tick, the precision threshold)
 * sys.peer jitter weighting corrected in sys_jitter calculation

ntpq

 * -n option extended to include the billboard "server" column
 * IPv6 addresses in the local column truncated to prevent overruns

--- 
NTP 4.2.6p4 (Harlan Stenn <stenn@ntp.org>, 2011/09/22) 
 
Focus: Bug fixes and portability improvements 
 
Severity: Medium 
 
This is a recommended upgrade. 
 
This release includes build infrastructure updates, code 
clean-ups, minor bug fixes, fixes for a number of minor 
ref-clock issues, and documentation revisions. 
 
Portability improvements affect AIX, HP-UX, Linux, OS X and 64-bit time_t. 
 
New features / changes in this release: 
 
Build system 
 
* Fix checking for struct rtattr 
* Update config.guess and config.sub for AIX 
* Upgrade required version of autogen and libopts for building 
  from our source code repository 
 
ntpd 
 
* Back-ported several fixes for Coverity warnings from ntp-dev 
* Fix a rare boundary condition in UNLINK_EXPR_SLIST() 
* Allow "logconfig =allall" configuration directive 
* Bind tentative IPv6 addresses on Linux 
* Correct WWVB/Spectracom driver to timestamp CR instead of LF 
* Improved tally bit handling to prevent incorrect ntpq peer status reports 
* Exclude the Undisciplined Local Clock and ACTS drivers from the initial 
  candidate list unless they are designated a "prefer peer" 
* Prevent the consideration of Undisciplined Local Clock or ACTS drivers for 
  selection during the 'tos orphanwait' period 
* Prefer an Orphan Mode Parent over the Undisciplined Local Clock or ACTS 
  drivers 
* Improved support of the Parse Refclock trusttime flag in Meinberg mode 
* Back-port utility routines from ntp-dev: mprintf(), emalloc_zero() 
* Added the NTPD_TICKADJ_PPM environment variable for specifying baseline 
  clock slew on Microsoft Windows 
* Code cleanup in libntpq 
 
ntpdc 
 
* Fix timerstats reporting 
 
ntpdate 
 
* Reduce time required to set clock 
* Allow a timeout greater than 2 seconds 
 
sntp 
 
* Backward incompatible command-line option change: 
  -l/--filelog changed -l/--logfile (to be consistent with ntpd) 
 
Documentation 
 
* Update html2man. Fix some tags in the .html files 
* Distribute ntp-wait.html 

---
NTP 4.2.6p3 (Harlan Stenn <stenn@ntp.org>, 2011/01/03)

Focus: Bug fixes and portability improvements

Severity: Medium

This is a recommended upgrade.

This release includes build infrastructure updates, code
clean-ups, minor bug fixes, fixes for a number of minor
ref-clock issues, and documentation revisions.

Portability improvements in this release affect AIX, Atari FreeMiNT,
FreeBSD4, Linux and Microsoft Windows.

New features / changes in this release:

Build system
* Use lsb_release to get information about Linux distributions.
* 'test' is in /usr/bin (instead of /bin) on some systems.
* Basic sanity checks for the ChangeLog file.
* Source certain build files with ./filename for systems without . in PATH.
* IRIX portability fix.
* Use a single copy of the "libopts" code.
* autogen/libopts upgrade.
* configure.ac m4 quoting cleanup.

ntpd
* Do not bind to IN6_IFF_ANYCAST addresses.
* Log the reason for exiting under Windows.
* Multicast fixes for Windows.
* Interpolation fixes for Windows.
* IPv4 and IPv6 Multicast fixes.
* Manycast solicitation fixes and general repairs.
* JJY refclock cleanup.
* NMEA refclock improvements.
* Oncore debug message cleanup.
* Palisade refclock now builds under Linux.
* Give RAWDCF more baud rates.
* Support Truetime Satellite clocks under Windows.
* Support Arbiter 1093C Satellite clocks under Windows.
* Make sure that the "filegen" configuration command defaults to "enable".
* Range-check the status codes (plus other cleanup) in the RIPE-NCC driver.
* Prohibit 'includefile' directive in remote configuration command.
* Fix 'nic' interface bindings.
* Fix the way we link with openssl if openssl is installed in the base
  system.

ntp-keygen
* Fix -V coredump.
* OpenSSL version display cleanup.

ntpdc
* Many counters should be treated as unsigned.

ntpdate
* Do not ignore replies with equal receive and transmit timestamps.

ntpq
* libntpq warning cleanup.

ntpsnmpd
* Correct SNMP type for "precision" and "resolution".
* Update the MIB from the draft version to RFC-5907.

sntp
* Display timezone offset when showing time for sntp in the local
  timezone.
* Pay proper attention to RATE KoD packets.
* Fix a miscalculation of the offset.
* Properly parse empty lines in the key file.
* Logging cleanup.
* Use tv_usec correctly in set_time().
* Documentation cleanup.

---
NTP 4.2.6p2 (Harlan Stenn <stenn@ntp.org>, 2010/07/08)

Focus: Bug fixes and portability improvements

Severity: Medium

This is a recommended upgrade.

This release includes build infrastructure updates, code
clean-ups, minor bug fixes, fixes for a number of minor
ref-clock issues, improved KOD handling, OpenSSL related
updates and documentation revisions.

Portability improvements in this release affect Irix, Linux,
Mac OS, Microsoft Windows, OpenBSD and QNX6

New features / changes in this release:

ntpd
* Range syntax for the trustedkey configuration directive
* Unified IPv4 and IPv6 restrict lists

ntpdate
* Rate limiting and KOD handling

ntpsnmpd
* default connection to net-snmpd via a unix-domain socket
* command-line 'socket name' option

ntpq / ntpdc
* support for the "passwd ..." syntax
* key-type specific password prompts

sntp
* MD5 authentication of an ntpd
* Broadcast and crypto
* OpenSSL support

---
NTP 4.2.6p1 (Harlan Stenn <stenn@ntp.org>, 2010/04/09)

Focus: Bug fixes, portability fixes, and documentation improvements

Severity: Medium

This is a recommended upgrade.

---
NTP 4.2.6 (Harlan Stenn <stenn@ntp.org>, 2009/12/08)

Focus: enhancements and bug fixes.

---
NTP 4.2.4p8 (Harlan Stenn <stenn@ntp.org>, 2009/12/08)

Focus: Security Fixes

Severity: HIGH

This release fixes the following high-severity vulnerability:

* [Sec 1331] DoS with mode 7 packets - CVE-2009-3563.

  See http://support.ntp.org/security for more information.

  NTP mode 7 (MODE_PRIVATE) is used by the ntpdc query and control utility.
  In contrast, ntpq uses NTP mode 6 (MODE_CONTROL), while routine NTP time
  transfers use modes 1 through 5.  Upon receipt of an incorrect mode 7
  request or a mode 7 error response from an address which is not listed
  in a "restrict ... noquery" or "restrict ... ignore" statement, ntpd will
  reply with a mode 7 error response (and log a message).  In this case:

	* If an attacker spoofs the source address of ntpd host A in a
	  mode 7 response packet sent to ntpd host B, both A and B will
	  continuously send each other error responses, for as long as
	  those packets get through.

	* If an attacker spoofs an address of ntpd host A in a mode 7
	  response packet sent to ntpd host A, A will respond to itself
	  endlessly, consuming CPU and logging excessively.

  Credit for finding this vulnerability goes to Robin Park and Dmitri
  Vinokurov of Alcatel-Lucent.

THIS IS A STRONGLY RECOMMENDED UPGRADE.

---
ntpd now syncs to refclocks right away.

Backward-Incompatible changes:

ntpd no longer accepts '-v name' or '-V name' to define internal variables.
Use '--var name' or '--dvar name' instead. (Bug 817)

---
NTP 4.2.4p7 (Harlan Stenn <stenn@ntp.org>, 2009/05/04)

Focus: Security and Bug Fixes

Severity: HIGH

This release fixes the following high-severity vulnerability:

* [Sec 1151] Remote exploit if autokey is enabled.  CVE-2009-1252

  See http://support.ntp.org/security for more information.

  If autokey is enabled (if ntp.conf contains a "crypto pw whatever"
  line) then a carefully crafted packet sent to the machine will cause
  a buffer overflow and possible execution of injected code, running
  with the privileges of the ntpd process (often root).

  Credit for finding this vulnerability goes to Chris Ries of CMU.

This release fixes the following low-severity vulnerabilities:

* [Sec 1144] limited (two byte) buffer overflow in ntpq.  CVE-2009-0159
  Credit for finding this vulnerability goes to Geoff Keating of Apple.
  
* [Sec 1149] use SO_EXCLUSIVEADDRUSE on Windows
  Credit for finding this issue goes to Dave Hart.

This release fixes a number of bugs and adds some improvements:

* Improved logging
* Fix many compiler warnings
* Many fixes and improvements for Windows
* Adds support for AIX 6.1
* Resolves some issues under MacOS X and Solaris

THIS IS A STRONGLY RECOMMENDED UPGRADE.

---
NTP 4.2.4p6 (Harlan Stenn <stenn@ntp.org>, 2009/01/07)

Focus: Security Fix

Severity: Low

This release fixes oCERT.org's CVE-2009-0021, a vulnerability affecting
the OpenSSL library relating to the incorrect checking of the return
value of EVP_VerifyFinal function.

Credit for finding this issue goes to the Google Security Team for
finding the original issue with OpenSSL, and to ocert.org for finding
the problem in NTP and telling us about it.

This is a recommended upgrade.
---
NTP 4.2.4p5 (Harlan Stenn <stenn@ntp.org>, 2008/08/17)

Focus: Minor Bugfixes 

This release fixes a number of Windows-specific ntpd bugs and 
platform-independent ntpdate bugs. A logging bugfix has been applied
to the ONCORE driver.

The "dynamic" keyword and is now obsolete and deferred binding to local 
interfaces is the new default. The minimum time restriction for the 
interface update interval has been dropped. 

A number of minor build system and documentation fixes are included. 

This is a recommended upgrade for Windows. 

---
NTP 4.2.4p4 (Harlan Stenn <stenn@ntp.org>, 2007/09/10)

Focus: Minor Bugfixes

This release updates certain copyright information, fixes several display
bugs in ntpdc, avoids SIGIO interrupting malloc(), cleans up file descriptor
shutdown in the parse refclock driver, removes some lint from the code,
stops accessing certain buffers immediately after they were freed, fixes
a problem with non-command-line specification of -6, and allows the loopback
interface to share addresses with other interfaces.

---
NTP 4.2.4p3 (Harlan Stenn <stenn@ntp.org>, 2007/06/29)

Focus: Minor Bugfixes

This release fixes a bug in Windows that made it difficult to
terminate ntpd under windows.
This is a recommended upgrade for Windows.

---
NTP 4.2.4p2 (Harlan Stenn <stenn@ntp.org>, 2007/06/19)

Focus: Minor Bugfixes

This release fixes a multicast mode authentication problem, 
an error in NTP packet handling on Windows that could lead to 
ntpd crashing, and several other minor bugs. Handling of 
multicast interfaces and logging configuration were improved. 
The required versions of autogen and libopts were incremented.
This is a recommended upgrade for Windows and multicast users.

---
NTP 4.2.4 (Harlan Stenn <stenn@ntp.org>, 2006/12/31)

Focus: enhancements and bug fixes.

Dynamic interface rescanning was added to simplify the use of ntpd in 
conjunction with DHCP. GNU AutoGen is used for its command-line options 
processing. Separate PPS devices are supported for PARSE refclocks, MD5 
signatures are now provided for the release files. Drivers have been 
added for some new ref-clocks and have been removed for some older 
ref-clocks. This release also includes other improvements, documentation 
and bug fixes. 

K&R C is no longer supported as of NTP-4.2.4. We are now aiming for ANSI 
C support.

---
NTP 4.2.0 (Harlan Stenn <stenn@ntp.org>, 2003/10/15)

Focus: enhancements and bug fixes.