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fwknop-2.0.4 (09/20/2012):
- [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 extras/openbsd/.
- [server] Bug fix to allow GPG_ALLOW_NO_PW to result in not also having
to specify a Rijndael key.
- [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.
- [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.
- 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 /usr/lib/. This allows the
test suite to run FKO tests without installing libfko.
- [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
closer to more OS default TTL values than the previous 255.
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
- [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
- [client] Fernando Arnaboldi from IOActive found a local buffer overflow
in --last processing with a maliciously constructed ~/ file.
This has been fixed with proper validation of 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
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:
- [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 'myip' cgi instance
in -R mode if the normal check against 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
[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
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/
by 0x4865667: pcap_dispatch (in /usr/lib/i386-linux-gnu/
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
- [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 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
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.
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