In the fw_config struct the active_rules member is unsigned, so this change
ensures that we don't try to decrement it below zero whenever a firewall rule
is deleted or an error condition occurs.
Replaced all instances of "_exp_" with the #define EXPIRE_COMMENT_PREFIX so
that the prefix can easily be changed. so
that the prefix can easily be changed. so
that the prefix can easily be changed. so
that the prefix can easily be changed.
This commit adds the ability to fwknopd to delete PF rules after the SPA timer
expires. The strategy implemented is similar to iptables and ipfw, except
that all PF rules are added to an 'anchor', and deleting a specific expired
rule is done by listing all rules in the anchor and reinstantiating it via
'pfctl -a <anchor> -f -' with the expired rule deleted. fwknopd uses the
"_exp_<expire time>" convention in a PF rule label similarly to how fwknopd
interfaces with iptables (via the 'comment' match), and ipfw (via the
"//<comment>" feature).
This commit implements the ability to add PF firewall rules to the fwknop
anchor after a valid SPA packet is sniffed off the wire. A subsequent commit
will add the ability to delete these rules.
This commit ensures that for PF firewalls that the fwknop anchor is active and
linked into the running PF policy. This is accomplished by looking for the
string 'anchor "fwknop"' in the output of "pfctl -s rules". If the anchor
exists, then fwknopd will be able to influence traffic via rules added and
removed from the fwknop anchor.
This commit fixes an issue on ipfw firewalls where fwknopd would always require
seeing ipfw 'Dynamic' rules associated with newly added connections. But, such
connections may never be established for various reasons. Previous to this
commit the following warning was frequently generated by fwknopd:
Unexpected error: did not find 'Dynamic rules' string in list output.
This commit fixes an issues on systems running the ipfw firewall where the
'set' where fwknopd puts new access rules was attempted to be deleted without
first checking to see whether it exists. The following errors would be
generated (now fixed):
ipfw: rule 16777217: setsockopt(IP_FW_DEL): Invalid argument
Error 17664 from cmd:'/sbin/ipfw delete set 1':
Fatal: Errors detected during ipfw rules initialization.
Bug fix to ensure that the digest.cache file gets created at fwknopd init time
so fwknopd does not throw the following error:
Error opening digest cache file. Incoming digests will not be remembered.
This change fixes the following compiler warning that was seen with many of
the source files in server/
fwknopd_common.h:223: warning: ‘config_map’ defined but not used
This commit fixes several compiler warnings like the following (now that -Wall
is the default):
config_init.h:68: warning: ‘cmd_opts’ defined but not used
Upon the receipt of a valid SPA packet, a check is done to make sure that
a jump rule from the appropriate built-in iptables chains exists to the
fwknop chains. Such rules could have been deleted by other manipulations
of the iptables policy, so it is important to ensure they exist. Running
in foreground (-f) mode, here is an illustration of the jump rule being
added after it got deleted:
SPA Packet from IP: 127.0.0.1 received.
Added jump rule from chain: INPUT to chain: FWKNOP_INPUT
Added Rule to FWKNOP_INPUT for 127.0.0.1, tcp/22 expires at 1313680648
Previous to this change a check was done for base64 characters in incoming
SPA data only up to MIN_SPA_DATA_SIZE. This check may be reinstantiated for
SPA packets that are delivered over HTTP (and the packet data is embedded
within a URL that may also contain non-base64 chars), but in the meantime the
fwknopd daemon should not accept SPA packets over arbitrary ports with any
non-base64 chars.
Replay warnings now include port and protocol information. Here is an example:
SPA Packet from IP: 127.0.0.1 received.
Replay detected from source IP: 127.0.0.1
Destination proto/port: 17/62201
Original source IP: 127.0.0.1
Original dst proto/port: 17/62201
Entry created: 08/17/11 21:06:07
First replay: 08/17/11 21:06:32
Last replay: 08/17/11 21:06:45
Replay count: 7
Upon fwknopd shutdown, a new function free_replay_list() is now called in order
to free heap allocated memory dedicated to SPA digest tracking. Without this
fix, valgrind reports the following (some output snipped):
valgrind --leak-check=full ./server/.libs/fwknopd -f -i lo -P "udp port 62201"
==30864== 431 (48 direct, 383 indirect) bytes in 1 blocks are definitely lost in loss record 17 of 17
==30864== at 0x4C27480: calloc (vg_replace_malloc.c:467)
==30864== by 0x407CB7: replay_check_file_cache (replay_cache.c:461)
==30864== by 0x407B69: replay_check (replay_cache.c:413)
==30864== by 0x405813: incoming_spa (incoming_spa.c:363)
==30864== by 0x406275: pcap_capture (pcap_capture.c:223)
==30864== by 0x40317D: main (fwknopd.c:297)
Added the source port and protocol fields to valid SPA packets in the digest
cache. This can help to discover replay trends. The format of the digest
file cache is now:
<digest> <proto> <src_ip> <src_port> <dst_ip> <dst_port> <time>
At init time fwknopd will read in the digest cache file into the in-memory
linked list of digests for SPA replay detection. This commit starts on this
code, but the file format does not yet include destination IP addresses
(to be added in an upcoming commit).
When not using gdbm/ndbm support (the default now), fwknopd implements a linked
list of SPA packet digests for replay attack detection along with writing
digest data in ascii text down to disk (in the CONF_DIGEST_FILE file).
To override the value of the PCAP_FILTER variable in the fwknopd.conf
config file, a new fwknopd command line argument "--pcap-filter" was
added. This assists in various activities by making it trivial to
change how fwknopd acquires packet data without editing the fwknopd.conf
file. Here is an example:
fwknopd -i lo -f --pcap-filter "udp port 12345"
If fwknopd is compiled with --disable-file-cache to the ./configure script
then it will assume that the default filename is "digest_db.cache" for the
digest cache. If the file cache method is used (this is the default), then
"digest.cache" is the default filename. A new variable DIGEST_DB_FILE in
the fwknopd.conf file controls the digest filename if gdbm/ndbm support is
required.
This change starts on support for a simple file-based cache mechanism
for tracking SPA digests. This removes the libgdbm/libndbm dependency
by default, but it can be re-enabled with the --disable-file-cache
argument to the ./configure script.
