ipf - alters packet filtering lists for IP packet input and output
] [ -l
] [ -T
<optionlist> ] [ -F
<i|o|a|s|S> ] -f
> [ -f
opens the filenames listed (treating "-" as stdin) and
parses the file for a set of rules which are to be added or removed from the
packet filter rule set.
Each rule processed by ipf
is added to the kernel's internal lists if
there are no parsing problems. Rules are added to the end of the internal
lists, matching the order in which they appear when given to ipf
- IPv4 and IPv6 rules are stored in a single table and can be read from a
single file. This option is no longer required to load IPv6 rules. This
option is ignored when specified with the -F option and the -F option will
flush IPv4 rules even if this option is specified.
- Set the list to make changes to the active list (default).
- -c <language>
- This option causes ipf to generate output files for a compiler that
supports language. At present, the only target language
supported is C (-cc) for which two files -
ip_rules.c and ip_rules.h are
generated in the CURRENT DIRECTORY when
ipf is being run. These files can be used with the
IPFILTER_COMPILED kernel option to build filter rules
staticlly into the kernel.
- Turn debug mode on. Causes a hexdump of filter rules to be generated as it
processes each one.
- Disable the filter (if enabled). Not effective for loadable kernel
- Enable the filter (if disabled). Not effective for loadable kernel
- -F <i|o|a>
- This option specifies which filter list to flush. The parameter should
either be "i" (input), "o" (output) or "a"
(remove all filter rules). Either a single letter or an entire word
starting with the appropriate letter maybe used. This option maybe before,
or after, any other with the order on the command line being that used to
- -F <s|S>
- To flush entries from the state table, the -F option is used in
conjunction with either "s" (removes state information about any
non-fully established connections) or "S" (deletes the entire
state table). Only one of the two options may be given. A fully
established connection will show up in ipfstat -s output as 5/5,
with deviations either way indicating it is not fully established any
- For the TCP states that represent the closing of a connection has begun,
be it only one side or the complete connection, it is possible to flush
those states directly using the number corresponding to that state. The
numbers relate to the states as follows: 5 = close-wait, 6 = fin-wait-1, 7
= closing, 8 = last-ack, 9 = fin-wait-2, 10 = time-wait, 11 = closed.
- If the argument supplied to -F is greater than 30, then state table
entries that have been idle for more than this many seconds will be
- -f <filename>
- This option specifies which files ipf should use to get input from
for modifying the packet filter rule lists.
- Set the list to make changes to the inactive list.
- -l <pass|block|nomatch>
- Use of the -l flag toggles default logging of packets. Valid
arguments to this option are pass, block and nomatch.
When an option is set, any packet which exits filtering and matches the
set category is logged. This is most useful for causing all packets which
don't match any of the loaded rules to be logged.
- This flag (no-change) prevents ipf from actually making any ioctl
calls or doing anything which would alter the currently running
- Force rules by default to be added/deleted to/from the output list, rather
than the (default) input list.
- Add rules as temporary entries in the authentication rule table.
- Remove matching filter rules rather than add them to the internal
- Swap the active filter list in use to be the "other" one.
- -T <optionlist>
- This option allows run-time changing of IPFilter kernel variables. Some
variables require IPFilter to be in a disabled state ( -D) for
changing, others do not. The optionlist parameter is a comma separated
list of tuning commands. A tuning command is either "list"
(retrieve a list of all variables in the kernel, their maximum, minimum
and current value), a single variable name (retrieve its current value)
and a variable name with a following assignment to set a new value. Some
# Print out all IPFilter kernel tunable parameters
ipf -T list
# Display the current TCP idle timeout and then set it to 3600
ipf -D -T fr_tcpidletimeout,fr_tcpidletimeout=3600 -E
# Display current values for fr_pass and fr_chksrc, then set fr_chksrc to 1.
ipf -T fr_pass,fr_chksrc,fr_chksrc=1
- Turn verbose mode on. Displays information relating to rule
- Show version information. This will display the version information
compiled into the ipf binary and retrieve it from the kernel code (if
running/present). If it is present in the kernel, information about its
current state will be displayed (whether logging is active, default
- Manually resync the in-kernel interface list maintained by IP Filter with
the current interface status list.
- For each rule in the input file, reset the statistics for it to zero and
display the statistics prior to them being zeroed.
- Zero global statistics held in the kernel for filtering only (this doesn't
affect fragment or state statistics).
ipftest(1), mkfilters(1), ipf(4), ipl(4), ipf(5), ipfstat(8), ipmon(8), ipnat(8)
Needs to be run as root for the packet filtering lists to actually be affected
inside the kernel.
If you find any, please send email to me at firstname.lastname@example.org