mdw@git.distorted.org.uk Git - firewall/blob - local.m4

   1 ### -*-sh-*-
   2 ###
   3 ### Local firewall configuration
   4 ###
   5 ### (c) 2008 Mark Wooding
   6 ###
   7
   8 ###----- Licensing notice ---------------------------------------------------
   9 ###
  10 ### This program is free software; you can redistribute it and/or modify
  11 ### it under the terms of the GNU General Public License as published by
  12 ### the Free Software Foundation; either version 2 of the License, or
  13 ### (at your option) any later version.
  14 ###
  15 ### This program is distributed in the hope that it will be useful,
  16 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ### GNU General Public License for more details.
  19 ###
  20 ### You should have received a copy of the GNU General Public License
  21 ### along with this program; if not, write to the Free Software Foundation,
  22 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  23
  24 ###--------------------------------------------------------------------------
  25 ### Packet classification.
  26
  27 ## Define the available network classes.
  28 m4_divert(42)m4_dnl
  29 defnetclass untrusted untrusted trusted
  30 defnetclass trusted untrusted trusted safe noloop
  31 defnetclass safe trusted safe noloop
  32 defnetclass noloop trusted safe
  33 m4_divert(-1)m4_dnl
  34
  35 ###--------------------------------------------------------------------------
  36 ### Network layout.
  37
  38 m4_divert(46)m4_dnl
  39 ## Networks and routing.
  40
  41 defiface $if_dmz \
  42         trusted:62.49.204.144/28 \
  43         trusted:172.29.199.0/25 \
  44         untrusted:default
  45 defiface $if_trusted \
  46         trusted:172.29.199.0/25 \
  47         untrusted:default
  48 defiface $if_safe safe:172.29.199.192/26
  49 defiface $if_untrusted \
  50         untrusted:172.29.198.0/25
  51 defvpn $if_vpn safe 172.29.199.128/27 \
  52         crybaby:172.29.199.129 \
  53         terror:172.29.199.130
  54 defiface $if_iodine untrusted:172.29.198.128/28
  55 defiface $if_its_mz safe:172.29.199.160/30
  56 defiface $if_its_pi safe:192.168.0.0/24
  57
  58 ## Default NTP servers.
  59 ntp_servers="158.152.1.76 158.152.1.204 194.159.253.2 195.173.57.232"
  60
  61 m4_divert(60)m4_dnl
  62 ###--------------------------------------------------------------------------
  63 ### Special forwarding exemptions.
  64
  65 ## Only allow these packets if they're not fragmented.  (Don't trust safe
  66 ## hosts's fragment reassembly to be robust against malicious fragments.)
  67 ## There's a hideous bug in iptables 1.4.11.1 which botches the meaning of
  68 ## `! -f', so we do the negation using early return from a subchain.
  69 clearchain fwd-spec-nofrag
  70 run iptables -A fwd-spec-nofrag -j RETURN --fragment
  71 run ip6tables -A fwd-spec-nofrag -j RETURN \
  72         -m ipv6header --soft --header frag
  73 run iptables -A FORWARD -j fwd-spec-nofrag
  74
  75 ## Allow ping from safe/noloop to untrusted networks.
  76 run iptables -A fwd-spec-nofrag -j ACCEPT \
  77         -p icmp --icmp-type echo-request \
  78         -m mark --mark $to_untrusted/$MASK_TO
  79 run iptables -A fwd-spec-nofrag -j ACCEPT \
  80         -p icmp --icmp-type echo-reply \
  81         -m mark --mark $from_untrusted/$MASK_FROM \
  82         -m state --state ESTABLISHED
  83 run ip6tables -A fwd-spec-nofrag -j ACCEPT \
  84         -p ipv6-icmp --icmpv6-type echo-request \
  85         -m mark --mark $to_untrusted/$MASK_TO
  86 run ip6tables -A fwd-spec-nofrag -j ACCEPT \
  87         -p ipv6-icmp --icmpv6-type echo-reply \
  88         -m mark --mark $from_untrusted/$MASK_FROM \
  89         -m state --state ESTABLISHED
  90
  91 ## Allow SSH from safe/noloop to untrusted networks.
  92 run iptables -A fwd-spec-nofrag -j ACCEPT \
  93         -p tcp --destination-port $port_ssh \
  94         -m mark --mark $to_untrusted/$MASK_TO
  95 run iptables -A fwd-spec-nofrag -j ACCEPT \
  96         -p tcp --source-port $port_ssh \
  97         -m mark --mark $from_untrusted/$MASK_FROM \
  98         -m state --state ESTABLISHED
  99 run ip6tables -A fwd-spec-nofrag -j ACCEPT \
 100         -p tcp --destination-port $port_ssh \
 101         -m mark --mark $to_untrusted/$MASK_TO
 102 run ip6tables -A fwd-spec-nofrag -j ACCEPT \
 103         -p tcp --source-port $port_ssh \
 104         -m mark --mark $from_untrusted/$MASK_FROM \
 105         -m state --state ESTABLISHED
 106
 107 m4_divert(60)m4_dnl
 108 ###--------------------------------------------------------------------------
 109 ### Kill things we don't understand properly.
 110 ###
 111 ### I don't like having to do this, but since I don't know how to do proper
 112 ### multicast filtering, I'm just going to ban it from being forwarded.
 113
 114 errorchain poorly-understood REJECT
 115
 116 ## Ban multicast destination addresses in forwarding.
 117 run iptables -A FORWARD -g poorly-understood \
 118         -d 224.0.0.0/4
 119 run ip6tables -A FORWARD -g poorly-understood \
 120         -d ff::/8
 121
 122 m4_divert(80)m4_dnl
 123 ###--------------------------------------------------------------------------
 124 ### Locally-bound packet inspection.
 125
 126 clearchain inbound
 127
 128 ## Track connections.
 129 commonrules inbound
 130 conntrack inbound
 131
 132 ## Allow incoming bootp.  Bootp won't be forwarded, so this is obviously a
 133 ## local request.
 134 run iptables -A inbound -j ACCEPT \
 135         -s 0.0.0.0 -d 255.255.255.255 \
 136         -p udp --source-port $port_bootpc --destination-port $port_bootps
 137 run iptables -A inbound -j ACCEPT \
 138         -s 172.29.198.0/23 \
 139         -p udp --source-port $port_bootpc --destination-port $port_bootps
 140
 141 ## Incoming multicast on a network interface associated with a trusted
 142 ## network is OK, since it must have originated there (or been forwarded, but
 143 ## we don't do that yet).
 144 for i in $(echo $if_trusted $if_dmz $if_safe | sed 'y/,/ /'); do
 145   echo $i
 146 done | {
 147   seen=:
 148   while read i; do
 149     case "$seen" in *:$i:*) continue ;; esac
 150     seen=$seen$i:
 151     run iptables -A inbound -j ACCEPT \
 152         -s 0.0.0.0 -d 224.0.0.0/24 \
 153         -i $i
 154   done
 155 }
 156
 157 ## Allow incoming ping.  This is the only ICMP left.
 158 run ip46tables -A inbound -j ACCEPT -p icmp
 159
 160 m4_divert(88)m4_dnl
 161 ## Allow unusual things.
 162 openports inbound
 163
 164 ## Inspect inbound packets from untrusted sources.
 165 run ip46tables -A inbound -j forbidden
 166 run ip46tables -A INPUT -m mark --mark $from_untrusted/$MASK_FROM -g inbound
 167
 168 ## Otherwise process as indicated by the mark.
 169 for i in INPUT FORWARD; do
 170   run ip46tables -A $i -m mark ! --mark 0/$MASK_MASK -j ACCEPT
 171 done
 172
 173 m4_divert(-1)
 174 ###----- That's all, folks --------------------------------------------------