freebsd 自带防火墙二（ipfilter）

相关文件：
/etc/rc.d/ipfilter
/etc/rc.d/ipfs
/etc/rc.d/ipmon


/dev/ipauth
/dev/ipl
/dev/ipstate

/sbin/ipf
/sbin/ipftest
/sbin/ippool

/sbin/ipnat 
/sbin/ipfstat 
/sbin/ipmon 
/sbin/ipfs 

/etc/ipf.rules
/var/log/ipfilter.log
/etc/ipf.rules.script

rc.conf:

ipfilter_enable="NO"        # Set to YES to enable ipfilter functionality
ipfilter_program="/sbin/ipf"    # where the ipfilter program lives
ipfilter_rules="/etc/ipf.rules"    # rules definition file for ipfilter, see
                # /usr/src/contrib/ipfilter/rules for examples
ipfilter_flags=""        # additional flags for ipfilter
ipnat_enable="NO"        # Set to YES to enable ipnat functionality
ipnat_program="/sbin/ipnat"    # where the ipnat program lives
ipnat_rules="/etc/ipnat.rules"    # rules definition file for ipnat
ipnat_flags=""            # additional flags for ipnat
ipmon_enable="NO"        # Set to YES for ipmon; needs ipfilter or ipnat
ipmon_program="/sbin/ipmon"    # where the ipfilter monitor program lives
ipmon_flags="-Ds"        # typically "-Ds" or "-D /var/log/ipflog"
ipfs_enable="NO"        # Set to YES to enable saving and restoring
                # of state tables at shutdown and boot
ipfs_program="/sbin/ipfs"    # where the ipfs program lives
ipfs_flags=""            # additional flags for ipfs

gateway_enable="YES"

内核：
options IPFILTER
options IPFILTER_LOG
options IPFILTER_DEFAULT_BLOCK