rc.firewall revision 15210 
1############
2# Setup system for firewall service.
3# $Id: rc.firewall,v 1.1 1996/04/03 17:13:58 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# If you just configured ipfw in the kernel as a tool to solve network
34# problems or you just want to disallow some particular kinds of traffic
35# they you will want to change the default policy to open.
36
37# /sbin/ipfw add 65000 pass all from any to any
38
39############
40# Only in rare cases do you want to change this rule
41/sbin/ipfw add 1000 pass all from 127.0.0.1 to 127.0.0.1
42
43############
44# This is a prototype setup that will protect your system somewhat against
45# people from outside your own network.
46#
47# To enable simply change "false" to "true" in the if line and set the
48# variables to your network parameters
49
50if false ; then
51    # set these to your network and netmask and ip
52    net="192.168.4.0"
53    mask="255.255.255.0"
54    ip="192.168.4.17"
55
56    # Allow any traffic to or from my own net.
57    /sbin/ipfw add pass all from ${ip} to ${net}:${mask}
58    /sbin/ipfw add pass all from ${net}:${mask} to ${ip}
59
60    # Allow TCP through if setup succeeded
61    /sbin/ipfw add pass tcp from any to any established
62
63    # Allow setup of incoming email 
64    /sbin/ipfw add pass tcp from any to ${ip} 25 setup
65
66    # Allow setup of outgoing TCP connections only
67    /sbin/ipfw add pass tcp from ${ip} to any setup
68
69    # Disallow setup of all other TCP connections
70    /sbin/ipfw add deny tcp from any to any setup
71
72    # Allow DNS queries out in the world
73    /sbin/ipfw add pass udp from any 53 to ${ip}
74    /sbin/ipfw add pass udp from ${ip} to any 53
75
76    # Allow NTP queries out in the world
77    /sbin/ipfw add pass udp from any 123 to ${ip}
78    /sbin/ipfw add pass udp from ${ip} to any 123
79
80    # Everyting else is denied as default.
81fi
82
83############
84# This is a prototype setup for a simple firewall.  Configure this machine 
85# as a named server and ntp server, and point all the machines on the inside
86# at this machine for those services.
87#
88# To enable simply change "false" to "true" in the if line and set the
89# variables to your network parameters
90
91if false ; then
92    # set these to your outside interface network and netmask and ip
93    oif="ed0"
94    onet="192.168.4.0"
95    omask="255.255.255.0"
96    oip="192.168.4.17"
97
98    # set these to your inside interface network and netmask and ip
99    iif="ed1"
100    inet="192.168.3.0"
101    imask="255.255.255.0"
102    iip="192.168.3.17"
103
104    # Stop spoofing
105    /sbin/ipfw add deny all from ${inet}:${imask} to any in via ${oif}
106    /sbin/ipfw add deny all from ${onet}:${omask} to any in via ${iif}
107
108    # Stop RFC1918 nets on the outside interface
109    /sbin/ipfw add deny all from 192.168.0.0:255.255.0.0 to any via ${oif}
110    /sbin/ipfw add deny all from 172.16.0.0:255.240.0.0 to any via ${oif}
111    /sbin/ipfw add deny all from 10.0.0.0:255.0.0.0 to any via ${oif}
112
113    # Allow TCP through if setup succeeded
114    /sbin/ipfw add pass tcp from any to any established
115
116    # Allow setup of incoming email 
117    /sbin/ipfw add pass tcp from any to ${oip} 25 setup
118
119    # Allow access to our DNS
120    /sbin/ipfw add pass tcp from any to ${oip} 53 setup
121
122    # Allow access to our WWW
123    /sbin/ipfw add pass tcp from any to ${oip} 80 setup
124
125    # Reject&Log all setup of incoming connections from the outside
126    /sbin/ipfw add deny log tcp from any to any in via ${oif} setup
127
128    # Allow setup of any other TCP connection
129    /sbin/ipfw add pass tcp from any to any setup
130
131    # Allow DNS queries out in the world
132    /sbin/ipfw add pass udp from any 53 to ${oip}
133    /sbin/ipfw add pass udp from ${oip} to any 53
134
135    # Allow NTP queries out in the world
136    /sbin/ipfw add pass udp from any 123 to ${oip}
137    /sbin/ipfw add pass udp from ${oip} to any 123
138
139    # Everyting else is denied as default.
140fi
141
142