rc.firewall revision 16578 
1############
2# Setup system for firewall service.
3# $Id: rc.firewall,v 1.2 1996/04/12 09:16:42 phk Exp $
4
5############
6#
7# >>Warning<<
8# This file is not very old yet, and have been put together without much
9# test of the contents.
10
11############
12#
13# If you don't know enough about packet filtering, we suggest that you
14# take time to read this book:
15#
16#	Building Internet Firewalls
17#	Brent Chapman and Elizabeth Zwicky
18#
19#	O'Reilly & Associates, Inc
20#	ISBN 1-56592-124-0
21#
22# For a more advanced treatment of Internet Security read:
23#
24#	Firewalls & Internet Security
25#	Repelling the wily hacker
26#	William R. Cheswick, Steven M. Bellowin
27#
28#	Addison-Wesley
29#	ISBN 0-201-6337-4
30#
31
32############
33# Flush out the list before we begin.
34/sbin/ipfw flush
35
36############
37# If you just configured ipfw in the kernel as a tool to solve network
38# problems or you just want to disallow some particular kinds of traffic
39# they you will want to change the default policy to open.
40
41# /sbin/ipfw add 65000 pass all from any to any
42
43############
44# Only in rare cases do you want to change this rule
45/sbin/ipfw add 1000 pass all from 127.0.0.1 to 127.0.0.1
46
47############
48# This is a prototype setup that will protect your system somewhat against
49# people from outside your own network.
50#
51# To enable simply change "false" to "true" in the if line and set the
52# variables to your network parameters
53
54if false ; then
55    # set these to your network and netmask and ip
56    net="192.168.4.0"
57    mask="255.255.255.0"
58    ip="192.168.4.17"
59
60    # Allow any traffic to or from my own net.
61    /sbin/ipfw add pass all from ${ip} to ${net}:${mask}
62    /sbin/ipfw add pass all from ${net}:${mask} to ${ip}
63
64    # Allow TCP through if setup succeeded
65    /sbin/ipfw add pass tcp from any to any established
66
67    # Allow setup of incoming email 
68    /sbin/ipfw add pass tcp from any to ${ip} 25 setup
69
70    # Allow setup of outgoing TCP connections only
71    /sbin/ipfw add pass tcp from ${ip} to any setup
72
73    # Disallow setup of all other TCP connections
74    /sbin/ipfw add deny tcp from any to any setup
75
76    # Allow DNS queries out in the world
77    /sbin/ipfw add pass udp from any 53 to ${ip}
78    /sbin/ipfw add pass udp from ${ip} to any 53
79
80    # Allow NTP queries out in the world
81    /sbin/ipfw add pass udp from any 123 to ${ip}
82    /sbin/ipfw add pass udp from ${ip} to any 123
83
84    # Everyting else is denied as default.
85fi
86
87############
88# This is a prototype setup for a simple firewall.  Configure this machine 
89# as a named server and ntp server, and point all the machines on the inside
90# at this machine for those services.
91#
92# To enable simply change "false" to "true" in the if line and set the
93# variables to your network parameters
94
95if false ; then
96    # set these to your outside interface network and netmask and ip
97    oif="ed0"
98    onet="192.168.4.0"
99    omask="255.255.255.0"
100    oip="192.168.4.17"
101
102    # set these to your inside interface network and netmask and ip
103    iif="ed1"
104    inet="192.168.3.0"
105    imask="255.255.255.0"
106    iip="192.168.3.17"
107
108    # Stop spoofing
109    /sbin/ipfw add deny all from ${inet}:${imask} to any in via ${oif}
110    /sbin/ipfw add deny all from ${onet}:${omask} to any in via ${iif}
111
112    # Stop RFC1918 nets on the outside interface
113    /sbin/ipfw add deny all from 192.168.0.0:255.255.0.0 to any via ${oif}
114    /sbin/ipfw add deny all from 172.16.0.0:255.240.0.0 to any via ${oif}
115    /sbin/ipfw add deny all from 10.0.0.0:255.0.0.0 to any via ${oif}
116
117    # Allow TCP through if setup succeeded
118    /sbin/ipfw add pass tcp from any to any established
119
120    # Allow setup of incoming email 
121    /sbin/ipfw add pass tcp from any to ${oip} 25 setup
122
123    # Allow access to our DNS
124    /sbin/ipfw add pass tcp from any to ${oip} 53 setup
125
126    # Allow access to our WWW
127    /sbin/ipfw add pass tcp from any to ${oip} 80 setup
128
129    # Reject&Log all setup of incoming connections from the outside
130    /sbin/ipfw add deny log tcp from any to any in via ${oif} setup
131
132    # Allow setup of any other TCP connection
133    /sbin/ipfw add pass tcp from any to any setup
134
135    # Allow DNS queries out in the world
136    /sbin/ipfw add pass udp from any 53 to ${oip}
137    /sbin/ipfw add pass udp from ${oip} to any 53
138
139    # Allow NTP queries out in the world
140    /sbin/ipfw add pass udp from any 123 to ${oip}
141    /sbin/ipfw add pass udp from ${oip} to any 123
142
143    # Everyting else is denied as default.
144fi
145
146