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IPFW(4)			    Kernel Interfaces Manual		       IPFW(4)

NAME
       ipfw -- IP packet filter	and traffic accounting

SYNOPSIS
       To compile ipfw into the	kernel,	place the following option in the ker-
       nel configuration file:

	     options IPFIREWALL

       Other kernel options related to ipfw which may also be useful are:

	     options IPFIREWALL_DEFAULT_TO_ACCEPT
	     options IPFIREWALL_FORWARD
	     options IPFIREWALL_VERBOSE
	     options IPFIREWALL_VERBOSE_LIMIT=100

       To  load	ipfw 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 oper-
       ations 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  mis-
       takes which may accidentally 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 De-
       nial 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.

       Policy routing and transparent forwarding features of ipfw can  be  en-
       abled by	IPFIREWALL_FORWARD kernel option.

       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)

FreeBSD	8.2		       September 1, 2006		       IPFW(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=ipfw&sektion=4&manpath=FreeBSD+8.2-RELEASE+and+Ports>

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