etc/rc.firewall

   1 #!/bin/sh -
   2 # Copyright (c) 1996  Poul-Henning Kamp
   3 # All rights reserved.
   4 #
   5 # Redistribution and use in source and binary forms, with or without
   6 # modification, are permitted provided that the following conditions
   7 # are met:
   8 # 1. Redistributions of source code must retain the above copyright
   9 #    notice, this list of conditions and the following disclaimer.
  10 # 2. Redistributions in binary form must reproduce the above copyright
  11 #    notice, this list of conditions and the following disclaimer in the
  12 #    documentation and/or other materials provided with the distribution.
  13 #
  14 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15 # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17 # ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18 # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19 # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20 # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21 # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23 # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24 # SUCH DAMAGE.
  25 #
  26 # $FreeBSD$
  27 #
  28
  29 #
  30 # Setup system for ipfw(4) firewall service.
  31 #
  32
  33 # Suck in the configuration variables.
  34 if [ -z "${source_rc_confs_defined}" ]; then
  35         if [ -r /etc/defaults/rc.conf ]; then
  36                 . /etc/defaults/rc.conf
  37                 source_rc_confs
  38         elif [ -r /etc/rc.conf ]; then
  39                 . /etc/rc.conf
  40         fi
  41 fi
  42
  43 ############
  44 # Define the firewall type in /etc/rc.conf.  Valid values are:
  45 #   open        - will allow anyone in
  46 #   client      - will try to protect just this machine
  47 #   simple      - will try to protect a whole network
  48 #   closed      - totally disables IP services except via lo0 interface
  49 #   workstation - will try to protect just this machine using statefull
  50 #                 firewalling. See below for rc.conf variables used
  51 #   UNKNOWN     - disables the loading of firewall rules.
  52 #   filename    - will load the rules in the given filename (full path required)
  53 #
  54 # For ``client'' and ``simple'' the entries below should be customized
  55 # appropriately.
  56
  57 ############
  58 #
  59 # If you don't know enough about packet filtering, we suggest that you
  60 # take time to read this book:
  61 #
  62 #       Building Internet Firewalls, 2nd Edition
  63 #       Brent Chapman and Elizabeth Zwicky
  64 #
  65 #       O'Reilly & Associates, Inc
  66 #       ISBN 1-56592-871-7
  67 #       http://www.ora.com/
  68 #       http://www.oreilly.com/catalog/fire2/
  69 #
  70 # For a more advanced treatment of Internet Security read:
  71 #
  72 #       Firewalls and Internet Security: Repelling the Wily Hacker, 2nd Edition
  73 #       William R. Cheswick, Steven M. Bellowin, Aviel D. Rubin
  74 #
  75 #       Addison-Wesley / Prentice Hall
  76 #       ISBN 0-201-63466-X
  77 #       http://www.pearsonhighered.com/
  78 #       http://www.pearsonhighered.com/educator/academic/product/0,3110,020163466X,00.html
  79 #
  80
  81 setup_loopback () {
  82         ############
  83         # Only in rare cases do you want to change these rules
  84         #
  85         ${fwcmd} add 100 pass all from any to any via lo0
  86         ${fwcmd} add 200 deny all from any to 127.0.0.0/8
  87         ${fwcmd} add 300 deny ip from 127.0.0.0/8 to any
  88 }
  89
  90 if [ -n "${1}" ]; then
  91         firewall_type="${1}"
  92 fi
  93
  94 ############
  95 # Set quiet mode if requested
  96 #
  97 case ${firewall_quiet} in
  98 [Yy][Ee][Ss])
  99         fwcmd="/sbin/ipfw -q"
 100         ;;
 101 *)
 102         fwcmd="/sbin/ipfw"
 103         ;;
 104 esac
 105
 106 ############
 107 # Flush out the list before we begin.
 108 #
 109 ${fwcmd} -f flush
 110
 111 setup_loopback
 112
 113 ############
 114 # Network Address Translation.  All packets are passed to natd(8)
 115 # before they encounter your remaining rules.  The firewall rules
 116 # will then be run again on each packet after translation by natd
 117 # starting at the rule number following the divert rule.
 118 #
 119 # For ``simple'' firewall type the divert rule should be put to a
 120 # different place to not interfere with address-checking rules.
 121 #
 122 case ${firewall_type} in
 123 [Oo][Pp][Ee][Nn]|[Cc][Ll][Ii][Ee][Nn][Tt])
 124         case ${natd_enable} in
 125         [Yy][Ee][Ss])
 126                 if [ -n "${natd_interface}" ]; then
 127                         ${fwcmd} add 50 divert natd ip4 from any to any via ${natd_interface}
 128                 fi
 129                 ;;
 130         esac
 131         case ${firewall_nat_enable} in
 132         [Yy][Ee][Ss])
 133                 if [ -n "${firewall_nat_interface}" ]; then
 134                         if echo "${firewall_nat_interface}" | \
 135                                 grep -q -E '^[0-9]+(\.[0-9]+){0,3}$'; then
 136                                 firewall_nat_flags="ip ${firewall_nat_interface} ${firewall_nat_flags}"
 137                         else
 138                                 firewall_nat_flags="if ${firewall_nat_interface} ${firewall_nat_flags}"
 139                         fi
 140                         ${fwcmd} nat 123 config log ${firewall_nat_flags}
 141                         ${fwcmd} add 50 nat 123 ip4 from any to any via ${firewall_nat_interface}
 142                 fi
 143                 ;;
 144         esac
 145 esac
 146
 147 ############
 148 # If you just configured ipfw in the kernel as a tool to solve network
 149 # problems or you just want to disallow some particular kinds of traffic
 150 # then you will want to change the default policy to open.  You can also
 151 # do this as your only action by setting the firewall_type to ``open''.
 152 #
 153 # ${fwcmd} add 65000 pass all from any to any
 154
 155
 156 # Prototype setups.
 157 #
 158 case ${firewall_type} in
 159 [Oo][Pp][Ee][Nn])
 160         ${fwcmd} add 65000 pass all from any to any
 161         ;;
 162
 163 [Cc][Ll][Ii][Ee][Nn][Tt])
 164         ############
 165         # This is a prototype setup that will protect your system somewhat
 166         # against people from outside your own network.
 167         #
 168         # Configuration:
 169         #  firewall_client_net:         Network address of local network.
 170         ############
 171
 172         # set this to your local network
 173         net="$firewall_client_net"
 174
 175         # Allow limited broadcast traffic from my own net.
 176         ${fwcmd} add pass all from ${net} to 255.255.255.255
 177
 178         # Allow any traffic to or from my own net.
 179         ${fwcmd} add pass all from me to ${net}
 180         ${fwcmd} add pass all from ${net} to me
 181
 182         # Allow TCP through if setup succeeded
 183         ${fwcmd} add pass tcp from any to any established
 184
 185         # Allow IP fragments to pass through
 186         ${fwcmd} add pass all from any to any frag
 187
 188         # Allow setup of incoming email
 189         ${fwcmd} add pass tcp from any to me 25 setup
 190
 191         # Allow setup of outgoing TCP connections only
 192         ${fwcmd} add pass tcp from me to any setup
 193
 194         # Disallow setup of all other TCP connections
 195         ${fwcmd} add deny tcp from any to any setup
 196
 197         # Allow DNS queries out in the world
 198         ${fwcmd} add pass udp from me to any 53 keep-state
 199
 200         # Allow NTP queries out in the world
 201         ${fwcmd} add pass udp from me to any 123 keep-state
 202
 203         # Everything else is denied by default, unless the
 204         # IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
 205         # config file.
 206         ;;
 207
 208 [Ss][Ii][Mm][Pp][Ll][Ee])
 209         ############
 210         # This is a prototype setup for a simple firewall.  Configure this
 211         # machine as a DNS and NTP server, and point all the machines
 212         # on the inside at this machine for those services.
 213         #
 214         # Configuration:
 215         #  firewall_simple_iif:         Inside network interface.
 216         #  firewall_simple_inet:        Inside network address.
 217         #  firewall_simple_oif:         Outside network interface.
 218         #  firewall_simple_onet:        Outside network address.
 219         ############
 220
 221         # set these to your outside interface network
 222         oif="$firewall_simple_oif"
 223         onet="$firewall_simple_onet"
 224
 225         # set these to your inside interface network
 226         iif="$firewall_simple_iif"
 227         inet="$firewall_simple_inet"
 228
 229         # Stop spoofing
 230         ${fwcmd} add deny all from ${inet} to any in via ${oif}
 231         ${fwcmd} add deny all from ${onet} to any in via ${iif}
 232
 233         # Stop RFC1918 nets on the outside interface
 234         ${fwcmd} add deny all from any to 10.0.0.0/8 via ${oif}
 235         ${fwcmd} add deny all from any to 172.16.0.0/12 via ${oif}
 236         ${fwcmd} add deny all from any to 192.168.0.0/16 via ${oif}
 237
 238         # Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
 239         # DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
 240         # on the outside interface
 241         ${fwcmd} add deny all from any to 0.0.0.0/8 via ${oif}
 242         ${fwcmd} add deny all from any to 169.254.0.0/16 via ${oif}
 243         ${fwcmd} add deny all from any to 192.0.2.0/24 via ${oif}
 244         ${fwcmd} add deny all from any to 224.0.0.0/4 via ${oif}
 245         ${fwcmd} add deny all from any to 240.0.0.0/4 via ${oif}
 246
 247         # Network Address Translation.  This rule is placed here deliberately
 248         # so that it does not interfere with the surrounding address-checking
 249         # rules.  If for example one of your internal LAN machines had its IP
 250         # address set to 192.0.2.1 then an incoming packet for it after being
 251         # translated by natd(8) would match the `deny' rule above.  Similarly
 252         # an outgoing packet originated from it before being translated would
 253         # match the `deny' rule below.
 254         case ${natd_enable} in
 255         [Yy][Ee][Ss])
 256                 if [ -n "${natd_interface}" ]; then
 257                         ${fwcmd} add divert natd all from any to any via ${natd_interface}
 258                 fi
 259                 ;;
 260         esac
 261
 262         # Stop RFC1918 nets on the outside interface
 263         ${fwcmd} add deny all from 10.0.0.0/8 to any via ${oif}
 264         ${fwcmd} add deny all from 172.16.0.0/12 to any via ${oif}
 265         ${fwcmd} add deny all from 192.168.0.0/16 to any via ${oif}
 266
 267         # Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
 268         # DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
 269         # on the outside interface
 270         ${fwcmd} add deny all from 0.0.0.0/8 to any via ${oif}
 271         ${fwcmd} add deny all from 169.254.0.0/16 to any via ${oif}
 272         ${fwcmd} add deny all from 192.0.2.0/24 to any via ${oif}
 273         ${fwcmd} add deny all from 224.0.0.0/4 to any via ${oif}
 274         ${fwcmd} add deny all from 240.0.0.0/4 to any via ${oif}
 275
 276         # Allow TCP through if setup succeeded
 277         ${fwcmd} add pass tcp from any to any established
 278
 279         # Allow IP fragments to pass through
 280         ${fwcmd} add pass all from any to any frag
 281
 282         # Allow setup of incoming email
 283         ${fwcmd} add pass tcp from any to me 25 setup
 284
 285         # Allow access to our DNS
 286         ${fwcmd} add pass tcp from any to me 53 setup
 287         ${fwcmd} add pass udp from any to me 53
 288         ${fwcmd} add pass udp from me 53 to any
 289
 290         # Allow access to our WWW
 291         ${fwcmd} add pass tcp from any to me 80 setup
 292
 293         # Reject&Log all setup of incoming connections from the outside
 294         ${fwcmd} add deny log tcp from any to any in via ${oif} setup
 295
 296         # Allow setup of any other TCP connection
 297         ${fwcmd} add pass tcp from any to any setup
 298
 299         # Allow DNS queries out in the world
 300         ${fwcmd} add pass udp from me to any 53 keep-state
 301
 302         # Allow NTP queries out in the world
 303         ${fwcmd} add pass udp from me to any 123 keep-state
 304
 305         # Everything else is denied by default, unless the
 306         # IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
 307         # config file.
 308         ;;
 309
 310 [Ww][Oo][Rr][Kk][Ss][Tt][Aa][Tt][Ii][Oo][Nn])
 311         # Configuration:
 312         #  firewall_myservices:         List of TCP ports on which this host
 313         #                                offers services.
 314         #  firewall_allowservices:      List of IPs which has access to
 315         #                                $firewall_myservices.
 316         #  firewall_trusted:            List of IPs which has full access
 317         #                                to this host. Be very carefull
 318         #                                when setting this. This option can
 319         #                                seriously degrade the level of
 320         #                                protection provided by the firewall.
 321         #  firewall_logdeny:            Boolean (YES/NO) specifying if the
 322         #                                default denied packets should be
 323         #                                logged (in /var/log/security).
 324         #  firewall_nologports:         List of TCP/UDP ports for which
 325         #                                denied incomming packets are not
 326         #                                logged.
 327
 328         # Allow packets for which a state has been built.
 329         ${fwcmd} add check-state
 330
 331         # For services permitted below.
 332         ${fwcmd} add pass tcp  from me to any established
 333
 334         # Allow any connection out, adding state for each.
 335         ${fwcmd} add pass tcp  from me to any setup keep-state
 336         ${fwcmd} add pass udp  from me to any       keep-state
 337         ${fwcmd} add pass icmp from me to any       keep-state
 338
 339         # Allow DHCP.
 340         ${fwcmd} add pass udp  from 0.0.0.0 68 to 255.255.255.255 67 out
 341         ${fwcmd} add pass udp  from any 67     to me 68 in
 342         ${fwcmd} add pass udp  from any 67     to 255.255.255.255 68 in
 343         # Some servers will ping the IP while trying to decide if it's
 344         # still in use.
 345         ${fwcmd} add pass icmp from any to any icmptype 8
 346
 347         # Allow "mandatory" ICMP in.
 348         ${fwcmd} add pass icmp from any to any icmptype 3,4,11
 349
 350         # Add permits for this workstations published services below
 351         # Only IPs and nets in firewall_allowservices is allowed in.
 352         # If you really wish to let anyone use services on your
 353         # workstation, then set "firewall_allowservices='any'" in /etc/rc.conf
 354         #
 355         # Note: We don't use keep-state as that would allow DoS of
 356         #       our statetable.
 357         #       You can add 'keep-state' to the lines for slightly
 358         #       better performance if you fell that DoS of your
 359         #       workstation won't be a problem.
 360         #
 361         for i in ${firewall_allowservices} ; do
 362           for j in ${firewall_myservices} ; do
 363             ${fwcmd} add pass tcp from $i to me $j
 364           done
 365         done
 366
 367         # Allow all connections from trusted IPs.
 368         # Playing with the content of firewall_trusted could seriously
 369         # degrade the level of protection provided by the firewall.
 370         for i in ${firewall_trusted} ; do
 371           ${fwcmd} add pass ip from $i to me
 372         done
 373
 374         ${fwcmd} add 65000 count ip from any to any
 375
 376         # Drop packets to ports where we don't want logging
 377         for i in ${firewall_nologports} ; do
 378           ${fwcmd} add deny { tcp or udp } from any to any $i in
 379         done
 380
 381         # Broadcasts and muticasts
 382         ${fwcmd} add deny ip  from any to 255.255.255.255
 383         ${fwcmd} add deny ip  from any to 224.0.0.0/24 in       # XXX
 384
 385         # Noise from routers
 386         ${fwcmd} add deny udp from any to any 520 in
 387
 388         # Noise from webbrowsing.
 389         # The statefull filter is a bit agressive, and will cause some
 390         #  connection teardowns to be logged.
 391         ${fwcmd} add deny tcp from any 80,443 to any 1024-65535 in
 392
 393         # Deny and (if wanted) log the rest unconditionally.
 394         log=""
 395         if [ ${firewall_logdeny:-x} = "YES" -o ${firewall_logdeny:-x} = "yes" ] ; then
 396           log="log logamount 500"       # The default of 100 is too low.
 397           sysctl net.inet.ip.fw.verbose=1 >/dev/null
 398         fi
 399         ${fwcmd} add deny $log ip from any to any
 400         ;;
 401
 402 [Cc][Ll][Oo][Ss][Ee][Dd])
 403         ${fwcmd} add 65000 deny ip from any to any
 404         ;;
 405 [Uu][Nn][Kk][Nn][Oo][Ww][Nn])
 406         ;;
 407 *)
 408         if [ -r "${firewall_type}" ]; then
 409                 ${fwcmd} ${firewall_flags} ${firewall_type}
 410         fi
 411         ;;
 412 esac