table of contents
IPFW(4) | Device Drivers Manual | IPFW(4) |
NAME¶
ipfw — IP packet filter and traffic accountingSYNOPSIS¶
To compile ipfw into the kernel, place the following option in the kernel 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:
options IPFIREWALL_FORWARD
options IPFIREWALL_VERBOSE
options IPFIREWALL_VERBOSE_LIMIT=100
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 theIPFIREWALL_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 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 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.
Policy routing and transparent forwarding features of ipfw can
be enabled 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)September 1, 2006 | Debian |