freebsd man page for ipfirewall

IPFW(4) 						   BSD Kernel Interfaces Manual 						   IPFW(4)

NAME
     ipfw -- IP packet filter and traffic accounting

SYNOPSIS
     To compile the driver into the kernel, place the following option in the kernel configuration file:

	   options IPFIREWALL

     Other related kernel options which may also be useful are:

	   options IPFIREWALL_DEFAULT_TO_ACCEPT
	   options IPFIREWALL_VERBOSE
	   options IPFIREWALL_VERBOSE_LIMIT=100

     To load the driver as a module at boot time, add the following line into the loader.conf(5) file:

	   ipfw_load="YES"

DESCRIPTION
     The ipfw system facility allows filtering, redirecting, and other operations on IP packets travelling through network interfaces.

     The default behavior of ipfw is to block all incoming and outgoing traffic.  This behavior can be modified, to allow all traffic through the
     ipfw firewall by default, by enabling the IPFIREWALL_DEFAULT_TO_ACCEPT kernel option.  This option may be useful when configuring ipfw for
     the first time.  If the default ipfw behavior is to allow everything, it is easier to cope with firewall-tuning mistakes which may acciden-
     tally block all traffic.

     To enable logging of packets passing through ipfw, enable the IPFIREWALL_VERBOSE kernel option.  The IPFIREWALL_VERBOSE_LIMIT option will
     prevent syslogd(8) from flooding system logs or causing local Denial of Service.  This option may be set to the number of packets which will
     be logged on a per-entry basis before the entry is rate-limited.

     The user interface for ipfw is implemented by the ipfw(8) utility, so please refer to the ipfw(8) manpage for a complete description of the
     ipfw capabilities and how to use it.

SEE ALSO
     setsockopt(2), divert(4), ip(4), ipfw(8), sysctl(8), syslogd(8), pfil(9)

BSD
								 October 25, 2012							       BSD