fwknop-2.6.10 (11//2016):
    - [server] Add MAX_FW_TIMEOUT to access.conf stanzas to allow a maximum
      number of seconds for client-specified timeouts in SPA packets. This
      fixes issue #226 which was spotted by Jeremiah Rothschild.
    - [server] Bug fix in CMD_EXEC mode to make sure to call exit() upon any
      error from execvpe(). Without this fix, additional fwknopd processes
      would be started upon a user specifying a command without the necessary
      permissions. This bug was reported by Stephen Isard.
    - [build] Jérémie Courrèges-Anglas and Ingo Feinerer contributed a patch
      to fix endian detection on OpenBSD systems based on information
      contained here: https://www.opengroup.org/austin/docs/austin_514.txt

fwknop-2.6.9 (06/08/2016):
    - (Jonathan Bennett) Added support for the SHA3 "Keccak" algorithm
      (specifically SHA3_256 and SHA3_512) for SPA HMAC and digest checking.
      Enabling SHA3 from the fwknop client command line is done with the '-m'
      option for the embedded SPA digest, or with the --hmac-digest-type
      argument for the HMAC. On the server side, SHA3_256 or SHA3_512 can be
      required for incoming SPA packet HMAC'c via the HMAC_DIGEST_TYPE
      configuration variable in access.conf stanzas. The SHA3 implementation
      is from, Keyak and Ketje Teams, namely, Guido Bertoni, Joan Daemen,
      Michael Peeters, Gilles Van Assche and Ronny Van Keer - see:
      http://keyak.noekeon.org/
    - (Damien Stuart) Added support for libnetfilter_queue so that fwknopd can
      acquire SPA packets via the NFQ target. This feature is enabled with a
      new command line switch '--enable-nfq-capture' for the configure script,
      and libpcap is not required in this mode. In support of capturing SPA
      packets via the NFQ target, new configuration variables have been added
      to the fwknopd.conf file: ENABLE_NFQ_CAPTURE, NFQ_INTERFACE, NFQ_PORT,
      NFQ_TABLE, NFQ_CHAIN, NFQ_QUEUE_NUMBER, and NFQ_LOOP_SLEEP.
    - (Vlad Glagolev) Added support for deriving the source IP from the
      X-Forwarded-For HTTP header when SPA packets are sent over HTTP
      connections.
    - Bug fix in command open/close cycle feature to ensure that the first
      successful match on a valid incoming SPA packet finishes all access.conf
      stanza processing. That is, no other stanzas should be looked at after
      the first match, and this is consistent with other SPA modes (such as
      basic access requests). This bug was reported by Jonathan Bennett.
    - (Jonathan Bennett) Various fixes and enhancements to the test suite to
      extend code coverage to new code, ensure valgrind bytes lost detection
      works for amount of memory less than 10 bytes, better timing strategy
      for fwknop client/server interactions, and more.

fwknop-2.6.8 (12/23/2015):
    - [server] Added a major new feature that allows fwknopd to easily
      integrate with third-party devices and software. This done through the
      addition of a generic "command open" and "command close" capability, and
      a set of variable substitutions are supported such as '$SRC', '$PORT',
      and '$PROTO'. This feature is designed to allow the user to switch out
      the default firewall - iptables, firewalld, ipfw, or PF - for something
      complete different. For example, here is a write-up on using this feature
      to integrate SPA operations with ipset:

        https://cipherdyne.org/blog/2015/12/single-packet-authorization-and-third-party-devices.html

    - [server] (Jonathan Bennett) Added new access.conf directives
      '%include <file>' and '%include_folder <directory>'. This allows more
      access stanzas to be defined in other locations in the filesystem, and
      this can be adventageous in some scenarios by letting non-privledged
      users define their own encryption and authentication keys for SPA
      operations. This way, users do not need write access to the main
      /etc/fwknop/access.conf file to change keys around or define new ones.
    - [server] Bug fix to not send the TCP server a TERM signal even when it is
      not running when fwknopd receives a HUP signal.
    - [libfko] Bug fix for a crash that could be triggered in
      fko_set_username() when a username that is 64 chars or longer is
      specified. This crash cannot be triggered in fwknopd even if an SPA
      packet contains such a username however due to additional protections in
      the SPA decoding routines. Further, this bug does not apply to the main
      fwknop client either because the maximal username size is truncated down
      below 64 bytes. Hence, this bug only applies to client-side software that
      is directly using libfko calling the fko_set_username() function.
    - [test suite] Code coverage is now at 90.7% counted by lines. The complete
      coverage report for the 2.6.8 release is available here:

        https://www.cipherdyne.org/fwknop/lcov-results/

fwknop-2.6.7 (08/24/2015):
    - [server] When command execution is enabled with ENABLE_CMD_EXEC for an
      access.conf stanza, added support for running commands via sudo. This was
      suggested by Github user 'freegigi' (issue #159) as a means to provide
      command filtering using the powerful sudoers syntax. This feature is
      implemented by prefixing any incoming command from a valid SPA packet
      with the sudo command along with optional user and group requirements
      as defined by the following new access.conf variables:
      ENABLE_CMD_SUDO_EXEC, CMD_SUDO_EXEC_USER, and CMD_SUDO_EXEC_GROUP.
    - [server] Kevin Layer reported a bug to the fwknop mailing list that
      simultaneous NAT access for two different access.conf stanza was not
      functioning properly. After some diagnosis, this was a result of
      rule_exists() not properly detecting and differentiating existing DNAT
      rules from new ones with different port numbers when 'iptables -C'
      support is not available. This was against iptables-1.4.7, and has been
      fixed in this release of fwknop (tracked as issue #162).
    - [server] Added --key-gen to fwknopd. This feature was suggested by
      Jonathan Bennett, and will help with ease of use efforts. The first
      platform to take advantage of this will likely be OpenWRT thanks to
      Jonathan.
    - [server] By default, fwknopd will now exit if the interface that it is
      sniffing goes down (patch contributed by Github user 'sgh7'). If this
      happens, it is expected that the native process monitoring feature in
      things like systemd or upstart will restart fwknopd. However, if fwknopd
      is not being monitored by systemd, upstart, or anything else, this
      behavior can be disabled with the EXIT_AT_INTF_DOWN variable in the
      fwknopd.conf file. If disabled, fwknopd will try to recover when a
      downed interface comes back up.
    - [extras] Added a script from Jonathan Bennett at
      extras/console-qr/console-qr.sh to generate QR codes from fwknopd
      access.conf keys.
    - [build] Added --with-firewalld to the autoconf configure script. This is
      a synonym for --with-firewall-cmd to avoid confusion. Some package
      maintainers use --with-firewalld to build fwknop.

fwknop-2.6.6 (04/23/2015):
    - [server] Add the ability for fwknopd to function as an generic SPA
      gateway. This allows scenarios such as the fwknopd system providing DHCP
      addresses to client systems, but those systems would be blocking by
      default from accessing the broader Internet until a valid SPA packet is
      sent to the gateway. Two new access.conf variables support this feature:
      DISABLE_DNAT (do not build any DNAT rules for forwarded connections) and
      FORWARD_ALL (allow all traffic to be forwarded instead of specific
      services requested within an SPA packet). So far, this feature is only
      supported on systems running iptables or firewalld. The idea was
      contributed by "spartan1833" to the fwknop mailing list, and this became
      issue 131 on github.
    - [server] Bug fix when compiled with --enable-udp-server to not include
      pcap.h, which is likely not installed whenever libpcap is also not
      installed. This bug was reported by Alexander Kozhevnikov.
    - [android] (Dan Brooks) Contributed a patch for the Android client app to
      add the definition of custom server udp port. This is similar to the
      --server-port argument offered by the main fwknop client.
    - [test suite] Handle versions of lcov that don't have the --rc argument
      which is normally used to force the creation of branch coverage stats
      when code coverage reports are created.
    - [build] Add --enable-asan-support to autoconf configure script to enable
      Google's Address Sanitizer (ASan) support. This feature is used during
      the testing phase for new fwknop releases. Running fwknop under the
      complete test suite (and also under AFL) with ASan support compiled in
      did not turn up any new bugs.
    - [test suite] (Franck Joncourt) Added libfko unit tests with the CUnit
      framework.
    - [test suite] Set AFL_HARDEN=1 to AFL fuzzing wrapper scripts. This
      enables simple memory bug detection in AFL at the cost of a small
      performance hit.

fwknop-2.6.5 (12/16/2014):
    - [server] (Grant Pannell) Added a new access.conf variable "DESTINATION"
      to define the destination address for which an SPA packet will be
      accepted. The string "ANY" is also accepted if a valid SPA packet should
      be honored to any destination IP. Similarly to the "SOURCE" variable,
      networks should be specified in CIDR notation (e.g. "192.168.10.0/24"),
      and individual IP addresses can be specified as well. Also, multiple IP's
      and/or networks can be defined as a comma separated list (e.g.
      "192.168.10.0/24,10.1.1.123").
    - [server] Bug fix to ensure that proper bounds are enforced when
      importing digest cache files from previous fwknopd executions. This bug
      was discovered through fuzzing with American Fuzzy Lop (AFL) as driven
      by the test/afl/fuzzing-wrappers/server-digest-cache.sh wrapper.
      Previous to this fix, fwknopd could be made to crash through a malicious
      digest cache file (normally in /var/run/fwknop/digest.cache) upon
      initial import. This crash can only be triggered by a local user on the
      system where fwknopd is deployed and who has write permissions to the
      digest.cache file - usually only root has these permissions.

fwknop-2.6.4 (11/16/2014):
    - [server] Added a UDP server mode so that SPA packets can be acquired via
      UDP directly without having to use libpcap. This is an optional feature
      since it opens a UDP port (and therefore requires the local firewall be
      opened for communications to this port), but fwknopd is careful to never
      send anything back to a client that sends data to this port. So, from the
      perspective of an attacker or scanner, fwknopd remains invisible. This
      feature is enabled in fwknopd either with a new command line argument
      --udp-server or in the fwknopd.conf file with the ENABLE_UDP_SERVER
      variable. When deployed in this mode, it is advisable to recompile fwknop
      beforehand with './configure --enable-udp-server' so that fwknopd does
      not link against libpcap.
    - [server] Replaced all popen() and system() calls with execvpe() with no
      usage of the environment. This is a defensive measure to not make use of
      the shell for firewall command execution, and is supported on systems
      where execvpe() is available.
    - (Gerry Reno) Added support for firewalld to the fwknopd daemon on RHEL 7
      and CentOS 7. This is implemented using the current firewalld '--direct
      --passthrough' capability which accepts raw iptables commands. More
      information on firewalld can be found here:

      https://fedoraproject.org/wiki/FirewallD

    - [server] Added support for the 'American Fuzzy Lop' (AFL) fuzzer from
      Michal Zalewski. This requires that fwknop is compiled with the
      '--enable-afl-fuzzing' argument to the configure script as this allows
      encryption/digest short circuiting in a manner necessary for AFL to
      function properly. The benefit of this strategy is that AFL can fuzz the
      SPA packet decoding routines implemented by libfko. See the test/afl/
      directory for some automation around AFL fuzzing.
    - (Bill Stubbs) submitted a patch to fix a bug where fwknopd could not
      handle Ethernet frames that include the Frame Check Sequence (FCS)
      header. This header is four bytes long, and is placed at the end of each
      Ethernet frame. Normally the FCS header is not visible to libpcap, but
      some card/driver combinations result in it being included. Bill noticed
      this on the following platform:

          BeagleBone Black rev C running 3.8.13-bone50 #1 SMP Tue May 13
          13:24:52 UTC 2014 armv7l GNU/Linux

    - [client] Bug fix to ensure that a User-Agent string can be specified
      when the fwknop client uses wget via SSL to resolve the external IP
      address. This closes issue #134 on github reported by Barry Allard. The
      fwknop client now uses the wget '-U' option to specify the User-Agent
      string with a default of "Fwknop/<version>". In addition, a new command
      line argument "--use-wget-user-agent" to allow the default wget
      User-Agent string to apply instead.
    - [python module] When an HMAC key is passed to spa_data_final() then
      default to HMAC SHA256 if no HMAC mode was specified.

fwknop-2.6.3 (07/28/2014):
    - [client] External IP resolution via '-R' (or '--resolve-ip-http') is now
      done via SSL by default. The IP resolution URL is now
      'https://www.cipherdyne.org/cgi-gin/myip', and a warning is generated
      in '-R' mode whenever a non-HTTPS URL is specified (it is safer just to
      use the default). The fwknop client leverages 'wget' for this operation
      since that is cleaner than having fwknop link against an SSL library.
    - Integrated the 'libfiu' fault injection library available from
      http://blitiri.com.ar/p/libfiu/  This feature is disabled by default,
      and requires the --enable-libfiu-support argument to the 'configure'
      script in order to enable it. With fwknop compiled against libfiu, fault
      injections are done at various locations within the fwknop sources and
      the test suite verifies that the faults are properly handled at run time
      via test/fko-wrapper/fko_fault_injection.c. In addition, the libfiu tool
      'fiu-run' is used against the fwknop binaries to ensure they handle
      faults that libfiu introduces into libc functions. For example, fiu-run
      can force malloc() to fail even without huge memory pressure on the
      local system, and the test suite ensures the fwknop binaries properly
      handle this.
    - [test suite] Integrated a new python fuzzer for fwknop SPA packets (see
      test/spa_fuzzing.py). This greatly extends the ability of the test suite
      to validate libfko operations since SPA fuzzing packets are sent through
      libfko routines directly (indendepently of encryption and
      authentication) with a special 'configure' option
      --enable-fuzzing-interfaces. The python fuzzer generates over 300K SPA
      packets, and when used by the test suite consumes about 400MB of disk.
      For reference, to use both the libfiu fault injection feature mentioned
      above and the python fuzzer, use the --enable-complete option to the
      test suite.
    - [test suite] With the libfiu fault injection support and the new python
      fuzzer, automated testing of fwknop achieves 99.7% function coverage and
      90.2% line coverage as determined by 'gcov'. The full report may be
      viewed here: http://www.cipherdyne.org/fwknop/lcov-results/
    - [server] Add a new GPG_FINGERPRINT_ID variable to the access.conf file
      so that full GnuPG fingerprints can be required for incoming SPA packets
      in addition to the appreviated GnuPG signatures listed in GPG_REMOTE_ID.
      From the test suite, an example fingerprint is

      GPG_FINGERPRINT_ID            00CC95F05BC146B6AC4038C9E36F443C6A3FAD56

    - [server] When validating access.conf stanzas make sure that one of
      GPG_REMOTE_ID or GPG_FINGERPRINT_ID is specified whenever GnuPG
      signatures are to be verified for incoming SPA packets. Signature
      verification is the default, and can only be disabled with
      GPG_DISABLE_SIG but this is NOT recommended.
    - [server] Bug fix for PF firewalls without ALTQ support on FreeBSD. With
      this fix it doesn't matter whether ALTQ support is available or not.
      Thanks to Barry Allard for discovering and reporting this issue.
      Closes issue #121 on github.
    - [server] Bug fix discovered with the libfiu fault injection tag
      "fko_get_username_init" combined with valgrind analysis. This bug is
      only triggered after a valid authenticated and decrypted SPA packet is
      sniffed by fwknopd:

        ==11181== Conditional jump or move depends on uninitialised value(s)
        ==11181==    at 0x113B6D: incoming_spa (incoming_spa.c:707)
        ==11181==    by 0x11559F: process_packet (process_packet.c:211)
        ==11181==    by 0x5270857: ??? (in /usr/lib/x86_64-linux-gnu/libpcap.so.1.4.0)
        ==11181==    by 0x114BCC: pcap_capture (pcap_capture.c:270)
        ==11181==    by 0x10F32C: main (fwknopd.c:195)
        ==11181==  Uninitialised value was created by a stack allocation
        ==11181==    at 0x113476: incoming_spa (incoming_spa.c:294)

    - [server] Bug fix to handle SPA packets over HTTP by making sure to honor
      the ENABLE_SPA_OVER_HTTP fwknopd.conf variable and to properly account
      for SPA packet lengths when delivered via HTTP.
    - [server] Add --test mode to instruct fwknopd to acquire and process
      SPA packets, but not manipulate firewall rules or execute commands that
      are provided by SPA clients. This option is mostly useful for the fuzzing
      tests in the test suite to ensure broad code coverage under adverse
      conditions.

fwknop-2.6.2 (04/28/2014):
    - [libfko] fix double free bug in SPA parser discovered with the new
      python SPA payload fuzzer (see the 'spa_encoding_fuzzing' branch which
      is not merged into the master branch yet).  This bug could be triggered
      in fwknopd with a malicious SPA payload, but only when GnuPG is used and
      when an attacker is in possession of valid GnuPG keys listed in the
      access.conf file. In other words, an arbitrary attacker cannot trigger
      this bug. Further, when Rijndael is used for SPA packet encryption, this
      bug cannot be triggered at all due to an length/format check towards the
      end of _rijndael_decrypt(). This bug was introduced in the 2.6.1
      development series, and no previous versions of fwknop are affected.

fwknop-2.6.1 (04/12/2014):
    - Updated copyright and authorship information to include a standard
      header which references both the AUTHORS and CREDITS files.  The
      specific language in this header was created by the Debian legal team at
      the request of Franck Joncourt.
    - [server] When GnuPG is used, the default now is to require that incoming
      SPA packets are signed by a key listed in GPG_REMOTE_ID for each
      access.conf stanza. In other words, the usage of GPG_REQUIRE_SIG is no
      longer necessary in order to authenticate SPA packets via the GnuPG
      signature. Verification of GnuPG signatures can be disabled with a new
      access.conf variable GPG_DISABLE_SIG, but this is NOT a recommended
      configuration.
    - [libfko] Bug fix to correct a memory leak in GnuPG SPA packet handling
      within the gpg_decrypt() function.  Here is the specific valgrind leak
      record that enabled the bug to be found (note that the new valgrind
      suppressions usage was critical for finding this bug among all other
      libgpgme memory leaks):

      ==23983== 1,044 bytes in 1 blocks are definitely lost in loss record 7 of 8
      ==23983==    at 0x4C2C494: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
      ==23983==    by 0x4E41D3A: gpg_decrypt (fko_encryption.c:422)
      ==23983==    by 0x4E42520: fko_decrypt_spa_data (fko_encryption.c:626)
      ==23983==    by 0x1155B0: incoming_spa (incoming_spa.c:519)
      ==23983==    by 0x1180A7: process_packet (process_packet.c:211)
      ==23983==    by 0x506D857: ??? (in /usr/lib/x86_64-linux-gnu/libpcap.so.1.4.0)
      ==23983==    by 0x117865: pcap_capture (pcap_capture.c:270)
      ==23983==    by 0x10F937: main (fwknopd.c:353)

    - [libfko] Better SPA packet dumping output to include GnuPG specifics
      whenever SPA packets are encrypted/authenticated via GnuPG.
    - [server] Validate SPA packet GnuPG signatures with the libfko
      fko_gpg_signature_id_match() function instead of server code doing this
      independently.
    - [client+server] Add --gpg-exe command line argument and GPG_EXE config
      variable to ~/.fwknoprc and the access.conf file so that the path to
      GnuPG can be changed from the default /usr/bin/gpg path.
    - [libfko] Allow usernames that are compatible with Microsoft guidelines as
      defined here: http://technet.microsoft.com/en-us/library/bb726984.aspx
      This allows for greater compatibility between fwknop clients on Windows
      (for example that may be deployed with Cygwin) and fwknopd on other
      systems.  This change was suggested by Gerry Reno, and closes Github
      issue #114.
    - [client] Minor bug fixes in 'udpraw' mode (normally used for spoofing the
      SPA source IP) to set a non-zero source port and to properly set the
      length field of the UDP header.
    - [test suite] Added valgrind suppressions for gpgme library function
      calls.
    - [test suite] Added the ability to run the 'lcov' tool against fwknop
      when compiled in --enable-profile-coverage mode.  This enabled lots of
      new tests to be developed for better code coverage.

fwknop-2.6.0 (01/12/2014):
    - (Radostan Riedel) Added an AppArmor policy for fwknopd that is known to
      work on Debian and Ubuntu systems.  The policy file is available at
      extras/apparmor/usr.sbin/fwknopd.
    - [libfko] Nikolay Kolev reported a build issue with Mac OS X Mavericks
      where local fwknop copies of strlcat() and strlcpy() were conflicting
      with those that already ship with OS X 10.9. Closes #108 on github.
    - [libfko] (Franck Joncourt) Consolidated FKO context dumping function into
      lib/fko_util.c. In addition to adding a shared utility function for
      printing an FKO context, this change also makes the FKO context output
      slightly easier to parse by printing each FKO attribute on a single line
      (this change affected the printing of the final SPA packet data).  The
      test suite has been updated to account for this change as well.
    - [libfko] Bug fix to not attempt SPA packet decryption with GnuPG without
      an fko object with encryption_mode set to FKO_ENC_MODE_ASYMMETRIC.  This
      bug was caught with valgrind validation against the perl FKO extension
      together with the set of SPA fuzzing packets in
      test/fuzzing/fuzzing_spa_packets.  Note that this bug cannot be
      triggered via fwknopd because additional checks are made within fwknopd
      itself to force FKO_ENC_MODE_ASYMMETRIC whenever an access.conf stanza
      contains GPG key information.  This fix strengthens libfko itself to
      independently require that the usage of fko objects without GPG key
      information does not result in attempted GPG decryption operations.
      Hence this fix applies mostly to third party usage of libfko - i.e.
      stock installations of fwknopd are not affected.  As always, it is
      recommended to use HMAC authenticated encryption whenever possible even
      for GPG modes since this also provides a work around even for libfko
      prior to this fix.
    - [Android] (Gerry Reno) Updated the Android client to be compatible with
      Android-4.4.
    - [Android] Added HMAC support (currently optional).
    - [server] Updated pcap_dispatch() default packet count from zero to 100.
      This change was made to ensure backwards compatibility with older
      versions of libpcap per the pcap_dispatch() man page, and also because
      some of a report from Les Aker of an unexpected crash on Arch Linux with
      libpcap-1.5.1 that is fixed by this change (closes #110).
    - [server] Bug fix for SPA NAT modes on iptables firewalls to ensure that
      custom fwknop chains are re-created if they get deleted out from under
      the running fwknopd instance.
    - [server] Added FORCE_SNAT to the access.conf file so that per-access
      stanza SNAT criteria can be specified for SPA access.
    - [test suite] added --gdb-test to allow a previously executed fwknop
      or fwknopd command to be sent through gdb with the same command line
      args as the test suite used.  This is for convenience to rapidly allow
      gdb to be launched when investigating fwknop/fwknopd problems.
    - [client] (Franck Joncourt) Added --stanza-list argument to show the
      stanza names from ~/.fwknoprc.
    - [libfko] (Hank Leininger) Contributed a patch to greatly extend libfko
      error code descriptions at various places in order to give much better
      information on what certain error conditions mean.  Closes #98.
    - [test suite] Added the ability to run perl FKO module built-in tests in
      the t/ directory underneath the CPAN Test::Valgrind module.  This allows
      valgrind memory checks to be applied to libfko functions via the perl
      FKO module (and hence rapid prototyping can be combined with memory leak
      detection).  A check is made to see whether the Test::Valgrind module
      has been installed, and --enable-valgrind is also required (or
      --enable-all) on the test-fwknop.pl command line.

fwknop-2.5.1 (07/25/2013):
    - [client] Bug fix to reset terminal setting to orignal values after
      entering keys via stdin.
    - [server] Bug fix to not print pid file existence warning.  Reported by
      Ilya Tumaykin to the fwknop list.
    - [test suite] Bug fix to not run an iptables Rijndael HMAC test on
      non-Linux systems.

fwknop-2.5 (07/19/2013):
    - ***** IMPORTANT *****:  If you are upgrading from an older version of
      fwknop, you will want to read the "Backwards Compatibility" section of
      the fwknop tutorial available here:

      http://www.cipherdyne.org/fwknop/docs/fwknop-tutorial.html#backwards-compatibility

      In summary, it is possible to have a mixed environment of fwknop-2.5
      clients and/or servers with older client and/or servers, but this
      requires some configuration in order to work properly.  On the server
      side, the directive "ENCRYPTION_MODE legacy" will need to be added to
      every access.conf stanza that uses Rijndael and that needs to support
      SPA packets from pre-2.5 clients.  On the client side when generating
      Rijndael-encrypted SPA packets for a pre-2.5 server, the command line
      argument "-M legacy" will need to be given.  GnuPG operations are not
      affected however and don't require the above steps whenever the new HMAC
      authenticated encryption feature (offered in fwknop-2.5) is not used.
    - Major release of new functionality - HMAC authenticated encryption
      support in the encrypt-then-authenticate model for SPA communications.
      Supported HMAC digests include MD5, SHA1, SHA256, SHA384, and SHA512.
      The default is HMAC-SHA256 when an HMAC is used.  The HMAC mode is
      supported for both Rijndael and GPG encrypted SPA packet data, and
      provides a significant security benefit for the fwknopd server since the
      HMAC verification is more simplisitic than decryption operations.  This
      is particularly true for GPG.  Beyond this, HMAC authenticated
      encryption in the encrypt-then-authenticate mode does not suffer from
      things like CBC-mode padding oracle attacks (see the Vaudenay attack and
      the more recent "Lucky 13" attack against SSL).  HMAC verifications are
      performed with a constant time comparison function.
    - [libfko] Significant bug fix to honor the full encryption key length for
      user-supplied Rijndael keys > 16 bytes long.  Previous to this fix,
      only the first 16 bytes of a key were actually used in the encryption/
      decryption process even if the supplied key was longer.  The result was
      a weakening of expected security for users that had keys > 16 bytes.
      Note that "passphrase" is perhaps technically a better word for
      "user-supplied key" in this context since the actual key is generated
      with the PBKDF1 key derivation algorithm.  This issue was reported by
      Michael T. Dean.  Closes issue #18 on github.
    - [libfko] Added the ability to maintain backwards compatibility with the
      now deprecated "zero padding" key derivation strategy in AES mode that
      was a hold over from the old perl fwknop implementation.  This is NOT
      compliant with PBKDF1 and is only brought forward into fwknop-2.5 for
      backwards compatibility.  Future versions of fwknop will remove this
      code altogether since PBKDF1 is now implemented.
    - [libfko+server] Ensure that all HMAC, digest, and other comparisons are
      done via a dedicated constant_runtime_cmp() function so that a potential
      attacker cannot gain any information about fail/success just by mounting
      a timing attack.  This function always compares two buffers from
      beginning to end regardless of whether a difference is detected early on
      in the comparison, and this strategy mirrors changes in SSL libraries
      such as yaSSL to protect against potential timing attacks.  This change
      fixes #85 on github which was reported by Ryman.
    - [test suite] Added --enable-openssl-checks to send all SPA packets
      encrypted via libfko through the OpenSSL library to ensure that the
      libfko usage of AES is always compatible with OpenSSL.  This ensures
      that the fwknop usage of AES is properly implemented as verified by the
      OpenSSL library, which is a frequently audited high profile crypto
      engine.  If a vulnerability is discovered in OpenSSL and a change is
      made, then the --enable-openssl-checks mode will allow the test suite to
      discover this in a automated fashion for fwknop.
    - The fwknop project is using Coverity for source code validation (in
      addition to other tools such as the CLANG static analyzer).  Many bugs
      have been fixed in this release that were discovered by Coverity.  These
      bugs spanned multiple classes of problems from memory leaks, improper use
      of sizeof(), potential double-free conditions, and more.  Full details on
      these fixes are available in the git history.  Any open source project
      that is written in a language supported by Coverity would benefit highly
      from participating.  As of the 2.5 release, fwknop has a Coverity defect
      score of zero.
    - [test suite] Changed how the test suite interacts with the fwknop client
      and server by looking for indications that SPA packets are actually
      received.  This is done by first waiting for 'main event loop' in fwknopd
      log output to ensure that fwknopd is ready to receive packets, sending
      the SPA packet(s), and then watching for for 'SPA Packet from IP' in
      fwknopd output.  This is an improvement over the previous strategy that
      was only based on timeout values since it works identically regardless of
      whether fwknop is being run under valgrind or when the test suite is run
      on an embedded system with very limited resources.  Another check is run
      for fwknopd receiving the SIGTERM signal to shutdown via 'fwknopd -K',
      and that failing, the test suite manually kills the process (though this
      should be rarely needed).  This change was implemented based on
      discussions with George Herlin.
    - (Franck Joncourt) Added support for resolving hostnames in various NAT
      modes (fixes issue #43 in github).
    - (Franck Joncourt) Bug fix in the client for resolving hostnames in '-P
      icmp' mode (fixes issue #64).
    - (Franck Joncourt) Added support for saving fwknop client command line
      arguments via a new options --save-rc-stanza.
    - (Franck Joncourt) Added log module support for the client.
    - [client] Bug fix for --nat-rand-port mode to ensure that the port to be
      NAT'd is properly defined so that the fwknopd server will NAT
      connnections to this port instead of applying the NAT operation to the
      port that is to be accessed via -A.  This change also prints the
      randomly assigned port to stdout regardless of whether --verbose mode is
      used (since if not then the user will have no idea which port is
      actually going to be NAT'd on the fwknopd side).
    - (Vlad Glagolev) Submitted an OpenBSD port for fwknop-2.0.4, and this has
      been checked in under the extras/openbsd/fwknop-2.0.4 directory.
    - (Shawn Wilson) Added better SPA source IP logging for various fwknopd
      logging messages.  This helps to make it more clear why certain SPA
      packets are rejected from some systems.
    - [client] Added --get-hmac-key to allow HMAC keys to be acquried from the
      specified file similarly to the --get-key option.  This is a convenience
      only, and the fwknop rc file feature should be used instead since it is
      far more powerful.

fwknop-2.0.4 (12/09/2012):
    - [client] Misc fixes and the addition of save_args and last command
      (.fwknop.last) support on the Windows platform.
    - [client] Fixed bug in username determination code where a valid value
      could be overrwritten in certain circumstances.
    - [server] Added upstart config at extras/upstart/fwknop.conf.  This
      allows the fwknopd to easily be managed with upstart via commands like
      "service fwknop start" and "service fwknop stop".
    - [server] (Vlad Glagolev) Submitted a patch to fix ndbm/gdbm usage when
      --disable-file-cache is used for the autoconf configure script.  This
      functionality was broken in be4193d734850fe60f14a26b547525ea0b9ce1e9
      through improper handling of #define macros from --disable-file-cache.
    - [server] (Vlad Glagolev) Submitted a patch to fix command exec mode
      under SPA message type validity test.  Support for command exec mode was
      also added to the test suite.
    - (Vlad Glagolev) Submitted an OpenBSD port for fwknop-2.0.3, and this has
      been checked in under the extras/openbsd/ directory.
    - [server] Bug fix to allow GPG_ALLOW_NO_PW to result in not also having
      to specify a Rijndael key.
    - [Android] Added new .properties files to allow the fwknop client to
      build and function properly on the latest Android release (4.1.2).
    - [client] Added '-P udpraw' to allow the client to send SPA packets over
      UDP with a spoofed source IP address.  This is in addition to the
      original 'tcpraw' and 'icmp' protocols that also support a spoofed
      source IP.
    - [libfko] Bug fix to check b64_decode() return value to ensure that
      non-base64 encoded data is never used.  Even though other validation
      routines checked decoded results, it is important to discard invalid
      data as early as possible.  Note too that such invalid data would only
      be provided to b64_decode() after proper decryption, so the client must
      provide authentic SPA data.
    - [libfko] Added validation of NAT access strings in the various NAT
      modes.
    - [libfko] Restricted usernames embedded in SPA packets to be
      alpha-numeric along with "-" chars.
    - [client] (Franck Joncourt) Contributed a patch to allow the fwknop
      client to be stopped during the password entry prompt with Ctrl-C before
      any SPA packet is sent on the wire.
    - [client+server] Applied patch from Franck Joncourt to remove unnecessary
      chmod() call when creating client rc file and server replay cache file.
      The permissions are now set appropriately via open(), and at the same
      time this patch fixes a potential race condition since the previous code
      used fopen() followed by chmod().
    - [server] Bug fix to accept SPA packets over ICMP if the fwknop client
      is executed with '-P icmp' and the user has the required privileges.
    - [test suite] Applied patch from Franck Joncourt to have the perl FKO
      module link against libfko in the local directory (if it exists) so that
      it doesn't have to have libfko completely installed in the /usr/lib/
      directory.  This allows the test suite to run FKO tests without
      installing libfko.
    - [test suite] Significant update to include a set of fuzzing SPA packets
      that are built using a patched version of libfko.  These packets are
      located in the test/fuzzing/bogus_spa_packets file, and are designed to
      ensure proper validation of SPA packet data.  This validation is
      performed in --enable-perl-module-checks mode via the perl FKO module.
    - [client] Added --icmp-type and --icmp-code arguments so the user can
      control the icmp type/code combination for spoofed SPA packets ('-P
      icmp') mode.
    - [client] Updated default TTL value to 64 for spoofed SPA packets.  This
      is closer to more OS default TTL values than the previous 255.
    - Updated build CFLAGS and LDFLAGS to conform to the Debian
      hardening-includes file for PIE support (e.g. '-fPIE' for CFLAGS and
      '-fPIE -pie' for LDFLAGS).
    - [test suite] For GnuPG tests that require a passphrase associated with
      a gpg key, added a pinentry check to see if the local gpg engine
      requires it.  If so, the gpg test that require a key are excluded since.
    - [server] Added a new '--pcap-file <file>' option to allow pcap files to
      be processed directly by fwknopd instead of sniffing an interface.  This
      feature is mostly intended for debugging purposes.
    - [server] Added chain_exists() check to SPA rule creation so that if any
      of the fwknop chains are deleted out from under fwknopd they will be
      recreated on the fly.  This mitigates scenarios where fwknopd might be
      started before a system level firewall policy is applied due to init
      script ordering, or if an iptables policy is re-applied without
      restarting fwknopd.

fwknop-2.0.3 (09/03/2012):
    - [server] Fernando Arnaboldi from IOActive found several DoS/code
      execution vulnerabilities for malicious fwknop clients that manage to
      get past the authentication stage (so a such a client must be in
      possession of a valid access.conf encryption key).  These vulnerabilities
      manifested themselves in the handling of malformed access requests, and
      both the fwknopd server code along with libfko now perform stronger input
      validation of access request data.  These vulnerabilities affect
      pre-2.0.3 fwknop releases.
    - [server] Fernando Arnaboldi from IOActive found a condition in which
      the server did not properly validate allow IP addresses from malicious
      authenticated clients.  This has been fixed with stronger allow IP
      validation.
    - [client+server] Fernando Arnaboldi from IOActive found that strict
      filesystem permissions for various fwknop files are not verified.  Added
      warnings whenever permissions are not strict enough, and ensured that
      files created by the fwknop client and server are only set to user
      read/write.
    - [client] Fernando Arnaboldi from IOActive found a local buffer overflow
      in --last processing with a maliciously constructed ~/.fwknop.run file.
      This has been fixed with proper validation of .fwknop.run arguments.
    - [server] Fernando Arnaboldi from IOActive found several conditions in
      which the server did not properly throw out maliciously constructed
      variables in the access.conf file.  This has been fixed along with new
      fuzzing tests in the test suite.
    - [test suite] Added a new fuzzing capability to ensure proper server-side
      input validation.  Fuzzing data is constructed with modified fwknop
      client code that is designed to emulate malicious behavior.
    - Fixed RPM builds by including the $(DESTDIR) prefix for uninstall-local
      and install-exec-hook stages in Makefile.am.

fwknop-2.0.2 (08/18/2012):
    - [server] For GPG mode, added a new access.conf variable
      "GPG_ALLOW_NO_PW" to make it possible to leverage a server-side GPG key
      pair that has no associated password.  This comes in handy when a system
      requires the user to leverage gpg-agent / pinentry which can present a
      problem in automated environments as required by the fwknopd server.
      Now, it might seem like a problem to remove the passphrase from a GPG
      key pair, but it's important to note that simply doing this is little
      worse than storing the passphrase in the clear on disk anyway in the
      access.conf file.  Further, this link helps provide additional detail:

      https://www.gnupg.org/faq/gnupg-faq.html#automated_use

    - [client] In IP resolution mode (-R) changed HTTP connection type to
      'close' since there is no need for connection persistence, and indeed the
      client expects to just get the IP and the connection to be closed.
      Jonathan Schulz submitted a patch for this.
    - [client] Bug fix to ensure that all data is read via recv() from a
      remote webserver IP resolution mode (-R).  Previously IP resolution
      could fail if HTTP headers were transferred separately from the data
      (for whatever reason).  Jonathan Schulz submitted a patch for this.
    - [client] Added backup check against a cipherdyne.com 'myip' cgi instance
      in -R mode if the normal check against cipherdyne.org fails.
    - [server] Bug fix to implement FLUSH_IPT_AT_INIT and FLUSH_IPT_AT_EXIT
      functionality.  These are enabled by default, and now iptables rules
      added by fwknopd can be made persistent by setting these variables to
      "N" in the fwknopd.conf file (this is not a recommended setting
      however).
      [server] Added FLUSH_IPFW_AT_INIT and FLUSH_IPFW_AT_EXIT for ipfw
      firewalls to emulate the corresponding functionality that is implemented
      for iptables firewalls.  This was suggested by Jonathan Schulz.
    - [server] Replay attack bug fix to ensure that an attacker cannot force a
      replay attack by intercepting an SPA packet and the replaying it with the
      base64 version of "Salted__" (for Rijndael) or the "hQ" prefix (for
      GnuPG).  This is an important fix.  The following comment was added into
      the fwknopd code:

      /* Ignore any SPA packets that contain the Rijndael or GnuPG prefixes
       * since an attacker might have tacked them on to a previously seen
       * SPA packet in an attempt to get past the replay check.  And, we're
       * no worse off since a legitimate SPA packet that happens to include
       * a prefix after the outer one is stripped off won't decrypt properly
       * anyway because libfko would not add a new one.
      */

    - [server] Fixed a memory leak bug in the replay attack detection code.
      The leak was found with the test suite in --enable-valgrind mode, and
      here is the valgrind trace that exposed it:

      44 bytes in 1 blocks are definitely lost in loss record 2 of 2
         at 0x482BE68: malloc (in
         /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
         by 0x490EA50: strdup (strdup.c:43)
         by 0x10CD69: incoming_spa (incoming_spa.c:162)
         by 0x10E000: process_packet (process_packet.c:200)
         by 0x4862E63: ??? (in /usr/lib/i386-linux-gnu/libpcap.so.1.1.1)
         by 0x4865667: pcap_dispatch (in /usr/lib/i386-linux-gnu/libpcap.so.1.1.1)
         by 0x10DABF: pcap_capture (pcap_capture.c:226)
         by 0x10A798: main (fwknopd.c:299)

    - [test suite] Added GPG tests for keyrings that have no associated
      passphrases.
    - [server] Implemented a new check to ensure that the iptables 'comment'
      match exists to ensure the proper environment for fwknopd operations.
      This check is controlled by the new ENABLE_IPT_COMMENT_CHECK variable,
      and was suggested by Hank Leininger.
    - [server] 'make install' fix to ensure restrictive permissions on the
      /etc/fwknop/ directory and /etc/fwknop/* files.  Also updated the 'make
      install' step to not overwrite any existing config files in /etc/fwknop/
      and instead install new copies from the source tree at
      /etc/fwknop/fwknopd.conf.inst and /etc/fwknop/access.conf.inst

fwknop-2.0.1 (07/23/2012):
    - [server] Bug fix where the same encryption key used for two stanzas in
      the access.conf file would result in access requests that matched the
      second stanza to always be treated as a replay attack.  This has been
      fixed for the fwknop-2.0.1 release, and was reported by Andy Rowland. Now
      the fwknopd server computes the SHA256 digest of raw incoming payload
      data before decryption, and compares this against all previous hashes.
      Previous to this commit, fwknopd would add a new hash to the replay
      digest list right after the first access.conf stanza match, so when SPA
      packet data matched the second access.conf stanza a matching replay
      digest would already be there.
    - [server] Updated PCAP_LOOP_SLEEP default to 1/10th of a second (in
      microseconds).  This was supposed to be the default anyway, but C
      Anthony Risinger reported a bug where fwknopd was consuming more
      resources than necessary, and the cause was PCAP_LOOP_SLEEP set by
      default to 1/100th of a second - this has been fixed.
    - [libfko] Added SPA message validation calls to fko decoding routines to
      help ensure that SPA messages conform to expected values.
    - Bug fix for PF firewalls: updated the PF anchor check to not rely on
      listing the PF policy - fwknopd now uses 'pfctl -s Anchor' instead.
    - [test suite] Added parsing of valgrind output to produce a listing of
      functions that have been flagged - this assists in the development
      process to ensure that fwknop is not leaking memory.
    - [test suite] Bug fix on Mac OS X systems to account for libfko.dylib path
      instead of libfko.so.  This fixes the existence check for libfko.
    - [test suite] Added tests for --nat-local mode.
    - [client] Fixed several minor memory leaks caught by valgrind.
    - [libfko] Minor gcc warning fix: fko_decode.c:43:17: warning: variable
      'edata_size' set but not used [-Wunused-but-set-variable].
    - Updated fwknopd init script for Debian systems (contributed by Franck
      Joncourt).

fwknop-2.0 (01/02/2012):
    - This is the first production release that has been completely re-written
      in C.  This brings Single Packet Authorization functionality to all sorts
      of machines from embedded devices to large systems.  iptables, ipfw, and
      pf firewalls are supported by the fwknopd daemon, and the fwknop client
      is known to work on most major *NIX environments, the iPhone and Android
      operating systems, and Cygwin under Windows.
    - Added FORCE_NAT mode to the access.conf file so that for any valid SPA
      packet, force the requested connection to be NAT'd through to the
      specified (usually internal) IP and port value.  This is useful if there
      are multiple internal systems running a service such as SSHD, and you
      want to give transparent access to only one internal system for each
      stanza in the access.conf file.  This way, multiple external users can
      each directly access only one internal system per SPA key.
    - Added two new access.conf variables are added "ACCESS_EXPIRE" and
      "ACCESS_EXPIRE_EPOCH" to allow access stanzas to be expired without
      having to modify the access.conf file and restart fwknopd.
    - Added a new feature to allow an access stanza that matches the SPA source
      address to not automatically short circuit other stanzas if there is an
      error (such as when there are multiple encryption keys involved and an
      incoming SPA packet is meant for, say, the second stanza and the first
      therefore doesn't allow proper decryption).
    - Bug fix to exclude SPA packets with timestamps in the future that are too
      great (old packets were properly excluded already).
    - Bug fix to honor the fwknop client --time-offset-plus and
      --time-offset-minus options
    - Added DNAT mode tests, minor memory leak fix in NAT mode, added fwknopd
      check for ENABLE_IPT_FORWARDING variable before attempting NAT access.
    - [test suite] Added --diff mode to compare results from one execution to
      the next.