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it will be output on its own line. Ns cancels this effect however. This change is also consistent with the rest of our manual pages.
97 lines
2.0 KiB
Groff
97 lines
2.0 KiB
Groff
.\"
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.\" $FreeBSD$
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.\"
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.Dd September 1, 2006
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.Dt IPFW 4
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.Os
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.Sh NAME
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.Nm ipfw
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.Nd IP packet filter and traffic accounting
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.Sh SYNOPSIS
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To compile
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the driver
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into the kernel, place the following option in the kernel configuration
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file:
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.Bd -ragged -offset indent
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.Cd "options IPFIREWALL"
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.Ed
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.Pp
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Other related kernel options
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which may also be useful are:
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.Bd -ragged -offset indent
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.Cd "options IPFIREWALL_DEFAULT_TO_ACCEPT"
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.Cd "options IPFIREWALL_FORWARD"
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.Cd "options IPFIREWALL_VERBOSE"
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.Cd "options IPFIREWALL_VERBOSE_LIMIT=100"
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.Ed
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.Pp
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To load
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the driver
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as a module at boot time, add the following line into the
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.Xr loader.conf 5
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file:
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.Bd -literal -offset indent
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ipfw_load="YES"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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system facility allows filtering,
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redirecting, and other operations on
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.Tn IP
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packets travelling through
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network interfaces.
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.Pp
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The default behavior of
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.Nm
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is to block all incoming and outgoing traffic.
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This behavior can be modified, to allow all traffic through the
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.Nm
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firewall by default, by enabling the
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.Dv IPFIREWALL_DEFAULT_TO_ACCEPT
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kernel option.
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This option may be useful when configuring
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.Nm
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for the first time.
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If the default
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.Nm
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behavior is to allow everything, it is easier to cope with
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firewall-tuning mistakes which may accidentally block all traffic.
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.Pp
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To enable logging of packets passing through
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.Nm ,
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enable the
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.Dv IPFIREWALL_VERBOSE
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kernel option.
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The
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.Dv IPFIREWALL_VERBOSE_LIMIT
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option will prevent
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.Xr syslogd 8
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from flooding system logs or causing local Denial of Service.
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This option may be set to the number of packets which will be logged on
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a per-entry basis before the entry is rate-limited.
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.Pp
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Policy routing and transparent forwarding features of
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.Nm
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can be enabled by
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.Dv IPFIREWALL_FORWARD
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kernel option.
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.Pp
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The user interface for
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.Nm
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is implemented by the
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.Xr ipfw 8
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utility, so please refer to the
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.Xr ipfw 8
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manpage for a complete description of the
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.Nm
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capabilities and how to use it.
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.Sh SEE ALSO
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.Xr setsockopt 2 ,
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.Xr divert 4 ,
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.Xr ip 4 ,
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.Xr ipfw 8 ,
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.Xr sysctl 8 ,
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.Xr syslogd 8 ,
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.Xr pfil 9
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