functions.m4, local.m4: Handle fragments in a useful way.

[firewall] / local.m4

### -*-m4-*-
###
### Local firewall configuration
###
### (c) 2008 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This program is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### This program is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with this program; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

###--------------------------------------------------------------------------
### Packet classification.

## Define the available network classes.
m4_divert(42)m4_dnl
defnetclass untrusted untrusted trusted
defnetclass trusted untrusted trusted safe noloop
defnetclass safe trusted safe noloop
defnetclass noloop trusted safe
m4_divert(-1)m4_dnl

###--------------------------------------------------------------------------
### Network layout.

m4_divert(46)m4_dnl
## Networks and routing.

defiface $if_trusted \
	trusted:172.29.199.0/26 \
	safe:172.29.199.64/27 \
	untrusted:default
defiface $if_untrusted \
	untrusted:172.29.198.0/24
defvpn $if_vpn safe 172.29.199.128/27 \
	crybaby:172.29.199.129
defiface $if_its_mz safe:172.29.199.160/30
defiface $if_its_pi safe:192.168.0.0/24

m4_divert(60)m4_dnl
###--------------------------------------------------------------------------
### Special forwarding exemptions.

## Allow ping from safe/noloop to untrusted networks.
run iptables -A FORWARD -j ACCEPT \
	-p icmp ! -f --icmp-type echo-request \
	-m mark --mark $to_untrusted/$MASK_TO
run iptables -A FORWARD -j ACCEPT \
	-p icmp ! -f --icmp-type echo-reply \
	-m mark --mark $from_untrusted/$MASK_FROM \
	-m state --state ESTABLISHED

## Allow SSH from safe/noloop to untrusted networks.
run iptables -A FORWARD -j ACCEPT \
    	-p tcp ! -f --destination-port $port_ssh \
	-m mark --mark $to_untrusted/$MASK_TO
run iptables -A FORWARD -j ACCEPT \
	-p tcp ! -f --source-port $port_ssh \
	-m mark --mark $from_untrusted/$MASK_FROM \
	-m state --state ESTABLISHED

m4_divert(80)m4_dnl
###--------------------------------------------------------------------------
### Locally-bound packet inspection.

clearchain inbound

## Track connections.
commonrules inbound
conntrack inbound

## Allow incoming bootp.  Bootp won't be forwarded, so this is obviously a
## local request.
run iptables -A inbound -j ACCEPT \
	-s 0.0.0.0 -d 255.255.255.255 \
	-p udp --source-port $port_bootpc --destination-port $port_bootps
run iptables -A inbound -j ACCEPT \
	-s 172.29.198.0/23 \
	-p udp --source-port $port_bootpc --destination-port $port_bootps

## Allow incoming ping.  This is the only ICMP left.
run iptables -A inbound -j ACCEPT -p icmp

m4_divert(88)m4_dnl
## Allow unusual things.
openports inbound

## Inspect inbound packets from untrusted sources.
run iptables -A inbound -j forbidden
run iptables -A INPUT -m mark --mark $from_untrusted/$MASK_FROM -g inbound

## Otherwise process as indicated by the mark.
for i in INPUT FORWARD; do
  run iptables -A $i -m mark ! --mark 0/$MASK_MASK -j ACCEPT
done

m4_divert(-1)
###----- That's all, folks --------------------------------------------------