#!/bin/sh
################ Start of IPFW rules file ###############################
# Flush out the list before we begin.
ipfw -q -f flush

# Set rules command prefix
cmd="ipfw -q add"
skip="skipto 800"
pif="bge0"    # public interface name of NIC
              # facing the public Internet
             
              #################################################################
              # No restrictions on Inside LAN Interface for private network
              # Change xl0 to your LAN NIC interface name
              #################################################################
              $cmd 005 allow all from any to any via em0
             
              #################################################################
              # No restrictions on Loopback Interface
              #################################################################
              $cmd 010 allow all from any to any via lo0
             
              #################################################################
              # check if packet is inbound and nat address if it is
              #################################################################
              $cmd 014 divert natd ip from any to any in via $pif
             
              #################################################################
              # Allow the packet through if it has previous been added to the
              # the "dynamic" rules table by a allow keep-state statement.
              #################################################################
              $cmd 015 check-state
             
              #################################################################
              # Interface facing Public Internet (Outbound Section)
              # Check session start requests originating from behind the
              # firewall on the private network or from this gateway server
              # destined for the public Internet.
              #################################################################
             
              # Allow out access to my ISP's Domain name server.
              # x.x.x.x must be the IP address of your ISP's DNS
              # Dup these lines if your ISP has more than one DNS server
              # Get the IP addresses from /etc/resolv.conf file
              $cmd 020 $skip tcp from any to 192.168.1.1 53 out via $pif setup keep-state
             
             
              # Allow out access to my ISP's DHCP server for cable/DSL configurations.
              $cmd 030 $skip udp from any to 192.168.1.1 67 out via $pif keep-state
             
              # Allow out non-secure standard www function
              $cmd 040 $skip tcp from any to any 80 out via $pif setup keep-state
             
              # Allow out secure www function https over TLS SSL
              $cmd 050 $skip tcp from any to any 443 out via $pif setup keep-state
             
              # Allow out send & get email function
              $cmd 060 $skip tcp from any to any 25 out via $pif setup keep-state
              $cmd 061 $skip tcp from any to any 110 out via $pif setup keep-state
             
              # Allow out FreeBSD (make install & CVSUP) functions
              # Basically give user root "GOD" privileges.
              $cmd 070 $skip tcp from me to any out via $pif setup keep-state uid root
             
              # Allow out ping
              $cmd 080 $skip icmp from any to any out via $pif keep-state
             
              # Allow out Time
              $cmd 090 $skip tcp from any to any 37 out via $pif setup keep-state
             
              # Allow out nntp news (i.e. news groups)
              $cmd 100 $skip tcp from any to any 119 out via $pif setup keep-state
             
              # Allow out secure FTP, Telnet, and SCP
              # This function is using SSH (secure shell)
              $cmd 110 $skip tcp from any to any 22 out via $pif setup keep-state
             
              # Allow out whois
              $cmd 120 $skip tcp from any to any 43 out via $pif setup keep-state
             
              # Allow ntp time server
              $cmd 130 $skip udp from any to any 123 out via $pif keep-state
             
              #################################################################
              # Interface facing Public Internet (Inbound Section)
              # Check packets originating from the public Internet
              # destined for this gateway server or the private network.
              #################################################################
             
              # Deny all inbound traffic from non-routable reserved address spaces
              $cmd 300 deny all from 192.168.0.0/16  to any in via $pif  #RFC 1918 private IP
              $cmd 301 deny all from 172.16.0.0/12   to any in via $pif  #RFC 1918 private IP
              $cmd 302 deny all from 10.0.0.0/8      to any in via $pif  #RFC 1918 private IP
              $cmd 303 deny all from 127.0.0.0/8     to any in via $pif  #loopback
              $cmd 304 deny all from 0.0.0.0/8       to any in via $pif  #loopback
              $cmd 305 deny all from 169.254.0.0/16  to any in via $pif  #DHCP auto-config
              $cmd 306 deny all from 192.0.2.0/24    to any in via $pif  #reserved for docs
              $cmd 307 deny all from 204.152.64.0/23 to any in via $pif  #Sun cluster
              $cmd 308 deny all from 224.0.0.0/3     to any in via $pif  #Class D & E multicast
             
              # Deny ident
              $cmd 315 deny tcp from any to any 113 in via $pif
             
              # Deny all Netbios service. 137=name, 138=datagram, 139=session
              # Netbios is MS/Windows sharing services.
              # Block MS/Windows hosts2 name server requests 81
              $cmd 320 deny tcp from any to any 137 in via $pif
              $cmd 321 deny tcp from any to any 138 in via $pif
              $cmd 322 deny tcp from any to any 139 in via $pif
              $cmd 323 deny tcp from any to any 81  in via $pif
             
              # Deny any late arriving packets
              $cmd 330 deny all from any to any frag in via $pif
             
              # Deny ACK packets that did not match the dynamic rule table
              $cmd 332 deny tcp from any to any established in via $pif
             
              # Allow traffic in from ISP's DHCP server. This rule must contain
              # the IP address of your ISP's DHCP server as it's the only
              # authorized source to send this packet type.
              # Only necessary for cable or DSL configurations.
              # This rule is not needed for 'user ppp' type connection to
              # the public Internet. This is the same IP address you captured
              # and used in the outbound section.
              $cmd 360 allow udp from 192.168.1.1 to any 68 in via $pif keep-state
             
              # Allow in standard www function because I have Apache server
              $cmd 370 allow tcp from any to me 80 in via $pif setup limit src-addr 2
             
              # Allow in secure FTP, Telnet, and SCP from public Internet
              $cmd 380 allow tcp from any to me 22 in via $pif setup limit src-addr 2
             
              # Allow in non-secure Telnet session from public Internet
              # labeled non-secure because ID & PW are passed over public
              # Internet as clear text.
              # Delete this sample group if you do not have telnet server enabled.
              $cmd 390 allow tcp from any to me 23 in via $pif setup limit src-addr 2
             
              # Reject & Log all unauthorized incoming connections from the public Internet
              $cmd 400 deny log all from any to any in via $pif
             
              # Reject & Log all unauthorized out going connections to the public Internet
              $cmd 450 deny log all from any to any out via $pif
             
              # This is skipto location for outbound stateful rules
              $cmd 800 divert natd ip from any to any out via $pif
              $cmd 801 allow ip from any to any
             
              # Everything else is denied by default
              # deny and log all packets that fell through to see what they are
              $cmd 999 deny log all from any to any
              ################ End of IPFW rules file ###############################