IPF(8)IPF(8)NAMEipf - alters packet filtering lists for IP packet input and output
SYNOPSISipf [ -6AcdDEInoPrsvVyzZ ] [ -l <block|pass|nomatch> ] [ -T <option‐
list> ] [ -F <i|o|a|s|S> ] -f <filename> [ -f <filename> [...]]
DESCRIPTIONipf 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
OPTIONS-6 This option is required to parse IPv6 rules and to have them
-A Set the list to make changes to the active list (default).
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 gen‐
erated as it processes each one.
-D Disable the filter (if enabled). Not effective for loadable
-E Enable the filter (if disabled). Not effective for loadable
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 start‐
ing 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.
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.
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 corre‐
sponding 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 sec‐
onds will be flushed.
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.
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.
-n This flag (no-change) prevents ipf from actually making any
ioctl calls or doing anything which would alter the currently
-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 inter‐
-s Swap the active filter list in use to be the "other" one.
This option allows run-time changing of IPFilter kernel vari‐
ables. Some variables require IPFilter to be in a disabled
state (-D) for changing, others do not. The optionlist parame‐
ter is a comma separated list of tuning commands. A tuning com‐
mand 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
# Print out all IPFilter kernel tunable parameters
# 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.
-v Turn verbose mode on. Displays information relating to rule
-V Show version information. This will display the version infor‐
mation compiled into the ipf binary and retrieve it from the
kernel code (if running/present). If it is present in the ker‐
nel, 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).
SEE ALSOipftest(1), mkfilters(1), ipf(4), ipl(4), ipf(5), ipfstat(8), ipmon(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