ipf

Alter packet filtering lists

Syntax:

ipf [-6AdDEInoPrsUvVyzZ] [-l block|pass|nomatch]  
[-F i|o|a|s|S] -f filename [-f filename [...]]

Options:

-6

Parse IPv6 rules and have them loaded.

-A

Set the list to make changes to the active list (default).

-d

Turn debug mode on. Cause a hexdump of filter rules 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.

-Fi|o|a

Specify which filter list to flush. The parameter should either be "i" (input), "o" (output) or "a" (remove all filter rules). Use either a single letter or an entire word starting with the appropriate letter.

-Fs|S

Flush entries from the state table. Use in conjunction with either s (removes state information about any non-fully established connections) or S (deletes the entire state table). A fully established connection show up in ipfstat -s with output as 4/4.

-f filename

Specify the 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.

-lpass|block|nomatch

Use of the -l flag toggles default logging of packets. Valid arguments to this option are pass, block, and nomatch.

-n

This flag (no-change) prevents ipf from actually making any ioctl() calls or doing anything that would alter the currently running kernel.

o

Force rules by default to add to or delete 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 the "other" list.

-U

Block packets traveling along the data stream which aren't recognized as IP packets. They are printed out on the console.

-v

Turn verbose mode on. Display information relating to rule processing.

-V

Show version information.

-y

Resync the in-kernel interface list maintained by IP Filter with the current interface status list.

-z

Reset the statistics to zero. Also, display the statistics before they are zeroed.

-Z

Hold the zero global statistics for filtering only (this doesn't affect fragment or state statistics).

Description:

The ipf utility opens the listed filenames (treating "-" as stdin) and parses the file for a set of rules 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.

Diagnostics

Depending on the error, the utility displays messages indicating:

• the specified interface doesn't exist
• the requested address is unknown
• the user isn't privileged and tried to alter an interface's configuration.

See also:

ipfs, ipfstat, ipmon, ipnat, lsm-ipfilter.so