############ # Setup system for firewall service. # $FreeBSD$ ############ # Define the firewall type in /etc/rc.conf. Valid values are: # open - will allow anyone in # client - will try to protect just this machine # simple - will try to protect a whole network # closed - totally disables IP services except via lo0 interface # UNKNOWN - disables the loading of firewall rules. # filename - will load the rules in the given filename (full path required) # # For ``client'' and ``simple'' the entries below should be customized # appropriately. ############ # # If you don't know enough about packet filtering, we suggest that you # take time to read this book: # # Building Internet Firewalls # Brent Chapman and Elizabeth Zwicky # # O'Reilly & Associates, Inc # ISBN 1-56592-124-0 # http://www.ora.com/ # # For a more advanced treatment of Internet Security read: # # Firewalls & Internet Security # Repelling the wily hacker # William R. Cheswick, Steven M. Bellowin # # Addison-Wesley # ISBN 0-201-6337-4 # http://www.awl.com/ # if [ "x$1" != "x" ]; then firewall_type=$1 fi ############ # Set quiet mode if requested if [ "x$firewall_quiet" = "xYES" ]; then fwcmd="/sbin/ipfw -q" else fwcmd="/sbin/ipfw" fi ############ # Flush out the list before we begin. $fwcmd -f flush ############ # If you just configured ipfw in the kernel as a tool to solve network # problems or you just want to disallow some particular kinds of traffic # they you will want to change the default policy to open. You can also # do this as your only action by setting the firewall_type to ``open''. # $fwcmd add 65000 pass all from any to any ############ # Only in rare cases do you want to change these rules $fwcmd add 1000 pass all from any to any via lo0 $fwcmd add 1010 deny all from 127.0.0.0/8 to 127.0.0.0/8 # Prototype setups. if [ "${firewall_type}" = "open" -o "${firewall_type}" = "OPEN" ]; then $fwcmd add 65000 pass all from any to any elif [ "${firewall_type}" = "client" ]; then ############ # This is a prototype setup that will protect your system somewhat against # people from outside your own network. ############ # set these to your network and netmask and ip net="192.168.4.0" mask="255.255.255.0" ip="192.168.4.17" # Allow any traffic to or from my own net. $fwcmd add pass all from ${ip} to ${net}:${mask} $fwcmd add pass all from ${net}:${mask} to ${ip} # Allow TCP through if setup succeeded $fwcmd add pass tcp from any to any established # Allow setup of incoming email $fwcmd add pass tcp from any to ${ip} 25 setup # Allow setup of outgoing TCP connections only $fwcmd add pass tcp from ${ip} to any setup # Disallow setup of all other TCP connections $fwcmd add deny tcp from any to any setup # Allow DNS queries out in the world $fwcmd add pass udp from any 53 to ${ip} $fwcmd add pass udp from ${ip} to any 53 # Allow NTP queries out in the world $fwcmd add pass udp from any 123 to ${ip} $fwcmd add pass udp from ${ip} to any 123 # Everything else is denied as default. elif [ "${firewall_type}" = "simple" ]; then ############ # This is a prototype setup for a simple firewall. Configure this machine # as a named server and ntp server, and point all the machines on the inside # at this machine for those services. ############ # set these to your outside interface network and netmask and ip oif="ed0" onet="192.168.4.0" omask="255.255.255.0" oip="192.168.4.17" # set these to your inside interface network and netmask and ip iif="ed1" inet="192.168.3.0" imask="255.255.255.0" iip="192.168.3.17" # Stop spoofing $fwcmd add deny all from ${inet}:${imask} to any in via ${oif} $fwcmd add deny all from ${onet}:${omask} to any in via ${iif} # Stop RFC1918 nets on the outside interface $fwcmd add deny all from 192.168.0.0:255.255.0.0 to any via ${oif} $fwcmd add deny all from 172.16.0.0:255.240.0.0 to any via ${oif} $fwcmd add deny all from 10.0.0.0:255.0.0.0 to any via ${oif} # Allow TCP through if setup succeeded $fwcmd add pass tcp from any to any established # Allow setup of incoming email $fwcmd add pass tcp from any to ${oip} 25 setup # Allow access to our DNS $fwcmd add pass tcp from any to ${oip} 53 setup # Allow access to our WWW $fwcmd add pass tcp from any to ${oip} 80 setup # Reject&Log all setup of incoming connections from the outside $fwcmd add deny log tcp from any to any in via ${oif} setup # Allow setup of any other TCP connection $fwcmd add pass tcp from any to any setup # Allow DNS queries out in the world $fwcmd add pass udp from any 53 to ${oip} $fwcmd add pass udp from ${oip} to any 53 # Allow NTP queries out in the world $fwcmd add pass udp from any 123 to ${oip} $fwcmd add pass udp from ${oip} to any 123 # Everything else is denied as default. elif [ "${firewall_type}" != "UNKNOWN" -a -r "${firewall_type}" ]; then $fwcmd ${firewall_type} fi