Updated: 2022/Sep/29
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IPMON(5) File Formats Manual IPMON(5)
NAME
ipmon, ipmon.conf - ipmon configuration file format
DESCRIPTION
The ipmon.conf file is optionally loaded by ipmon when it starts. Its
primary purpose is to direct ipmon to do extra actions when it sees a
specific log entry from the kernel.
A line in the ipmon.conf file is either a comment or a match line.
Each line must have a matching segment and an action segment. These
are to the left and right of the word "do", respectively. A comment
line is any line that starts with a #.
NOTE: This file differs from all other IPFilter configuration files
because it attempts to match every line with every log record received.
It does not stop at the first match or only use the last match.
For the action segment, a match line can delivery output to one of
three destinations: file, email or command. For example:
match { type = ipf; } do { save("file:///var/log/ipf-log"); };
match { type = nat; } do { syslog; };
match { type = state; } do { execute("/bin/mail root"); };
and is roughly described like this:
match { match-it ,match-it, ... } do { action, action, ...};
where there can be a list of matching expressions and a list of actions
to perform if all of the matching expressions are matched up with by
the current log entry.
The lines above would save all ipf log entries to /var/log/ipf-log,
send all of the entries for NAT (ipnat related) to syslog and generate
an email to root for each log entry from the state tables.
SYNTAX - MATCHING
In the above example, the matching segment was confined to matching on
the type of log entry generated. The full list of fields that can be
used here is:
direction <in|out>
This option is used to match on log records generated for
packets going in or out.
dstip <address/mask>
This option is used to match against the destination address
associated with the packet being logged. A "/mask" must be
given and given in CIDR notation (/0-/32) so to specify host
192.2.2.1, 192.2.2.1/32 must be given.
dstport <portnumber>
This option is used to match against the destination port in log
entries. A number must be given, symbolic names (such as those
from /etc/services) are not recognised by the parser.
every <second|# seconds|packet|# packets>
This option is used to regulate how often an ipmon.conf entry is
actioned in response to an otherwise matching log record from
the kernel.
group <name|number>
interface <interface-name>
This option is used to match against the network interface name
associated with the action causing the logging to happen. In
general this will be the network interface where the packet is
seen by IPFilter.
logtag <number>
This option is used to match against tags set by ipf rules in
ipf.conf. These tags are set with "set-tag(log=100)" appended
to filter rules.
nattag <string>
This option is used to match against tags set by NAT rules in
ipnat.conf.
protocol <name|number>
This option is used to match against the IP protocol field in
the packet being logged.
result <pass|block|nomatch|log>
This option is used to match against the result of packet
matching in the kernel. If a packet is logged, using a log rule
in ipf.conf then it will match "log" here. The "nomatch" option
is for use with matching log records generated for all packets
as the default.
rule <number>
This option is used to match against the number of the rule
causing the record to be generated. The number of a rule can be
observed using "ipfstat -ion".
srcip <address/mask>
This option is used to match against the source address
associated with the packet being logged. A "/mask" must be
given and given in CIDR notation (/0-/32) so to specify host
192.2.2.1, 192.2.2.1/32 must be given.
srcport <portnumber>
This option is used to match against the source port in log
entries. A number must be given, symbolic names (such as those
from /etc/services) are not recognised by the parser.
type <ipf|nat|state>
The format for files accepted by ipmon is described by the
following grammar: NOTE: At present, only IPv4 matching is
available for source/destination address matching.
SYNTAX - ACTIONS
The list of actions supported is as follows:
save("file://<filename>")
save("raw://<filename>") Write out the log record to the
filename given. This file will be closed and reopened on
receipt of a SIGHUP. If the raw target is used, binary log
data, as read from the kernel, is written out rather than a text
log record. The filename should be an absolute target, including
the root directory. Thus, saving to /var/log/ipmon.log would be,
as an example, save("file:///var/log/ipmon.log").
syslog("<facility>.<priority>")
syslog("<facility>.") syslog(".<priority>") To log a text record
via syslog, the syslog action word is used. The facility used
by default is determined at first by the default compiled into
ipmon (usually LOG_LOCAL0), which can be changed via the command
line (-L <facility>) or in an ipf.conf rule using the level
option with logging. If the facility is specified here, it
takes precedence over all other settings. The same applies to
the syslog priority. By default, ipmon will determine a priority
for the packet, depending on whether or not it has been blocked,
passed, etc. It is possible to force the complete
facility/priority value for each log entry or to choose to
replace only one of them.
execute("<command string>")
The execute action runs the specified command each time the log
entry matches and feeds the log entry, as text, to the command
being executed. The command string given is executed using
/bin/sh.
nothing
Literally, do nothing. Use this if you want to be verbose in
your config file about doing nothing for a particular log
record.
PLUGIN ACTIONS
It is possible to configure ipmon to use externally supplied modules to
save log entries with. These are added to ipmon using the load_action
configuration line. The syntax of this line is:
load_action <name> <path>;
name is a short name for the action. It does not need to correspond
to the name of the library file, but inside the library file,
the functions <name>destroy , <name>parse and <name>store must
be present.
path specifies the path in the filesystem to the shared object that
contains the implementation of the new action. After the new
action has been declared using load_action it can then be used
in any do statement.
EXAMPLES
Some further examples are:
#
# log everything to syslog local4, regardless
#
match { ; } do { syslog("local4."); };
#
# keep a local copy of things packets to/from port 80
#
match { srcport = 80; } do { save("file:///var/log/web"); };
match { dstport = 80; } do { save("file:///var/log/web"); };
#
load_action local "/usr/lib/libmyaction.so";
match { dstip 127.0.0.1; } do { local("local options"); };
#
MATCHING
All entries of the rules present in the file are compared for matches -
there is no first or last rule match.
FILES
/dev/ipl
/dev/ipf
/dev/ipnat
/dev/ipstate
/etc/ipmon.conf
SEE ALSO
ipmon(8), ipl(4)
IPMON(5)