Updated: 2022/Sep/29
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IPF(8) System Manager's Manual IPF(8)
NAME
ipf - alters packet filtering lists for IP packet input and output
SYNOPSIS
ipf [ -6AcdDEInoPrsvVyzZ ] [ -l <block|pass|nomatch> ] [ -T
<optionlist> ] [ -F <i|o|a|s|S> ] -f <filename> [ -f <filename> [...]]
DESCRIPTION
ipf 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.
OPTIONS
-6 This option is required to parse IPv6 rules and to have them
loaded.
-A 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 staticly into the kernel.
-d Turn debug mode on. Causes a hexdump of filter rules to be
generated as it processes each one.
-D Disable the filter (if enabled). Not effective for loadable
kernel versions.
-E Enable the filter (if disabled). Not effective for loadable
kernel versions.
-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 execute options.
-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 more.
-F<5|6|7|8|9|10|11>
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.
-F<number>
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 flushed.
-f <filename>
This option specifies which files ipf should use to get input
from for modifying the packet filter rule lists.
-I Set the list to make changes to the inactive list.
-l <block|pass|nomatch|none|state|nat>
Use of the -l flag toggles default logging of packets. Valid
arguments to this option are pass, block, nomatch, none, state,
and nat. 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.
-n This flag (no-change) prevents ipf from actually making any
ioctl calls or doing anything which would alter the currently
running kernel.
-o Force rules by default to be added/deleted to/from the output
list, rather than the (default) input list.
-P Add rules as temporary entries in the authentication rule table.
-r Remove matching filter rules rather than add them to the
internal lists
-s 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 examples follow.
# 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
-v Turn verbose mode on. Displays information relating to rule
processing.
-V 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 filtering, etc).
-y Manually resync the in-kernel interface list maintained by IP
Filter with the current interface status list.
-z For each rule in the input file, reset the statistics for it to
zero and display the statistics prior to them being zeroed.
-Z Zero global statistics held in the kernel for filtering only
(this doesn't affect fragment or state statistics).
FILES
/dev/ipauth
/dev/ipl
/dev/ipstate
SEE ALSO
ipftest(1), mkfilters(1), ipf(4), ipl(4), ipf(5), ipfstat(8), ipmon(8),
ipnat(8)
DIAGNOSTICS
Needs to be run as root for the packet filtering lists to actually be
affected inside the kernel.
BUGS
If you find any, please send email to me at darrenr@pobox.com
IPF(8)