-### -*-m4-*-
+### -*-sh-*-
###
### Local firewall configuration
###
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
###--------------------------------------------------------------------------
+### Local configuration.
+
+m4_divert(6)m4_dnl
+## Default NTP servers.
+defconf(ntp_servers,
+ "158.152.1.76 158.152.1.204 194.159.253.2 195.173.57.232")
+
+m4_divert(-1)
+###--------------------------------------------------------------------------
### 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
+defnetclass untrusted untrusted mcast
+defnetclass link
+defnetclass mcast
+m4_divert(-1)
+
+m4_divert(26)m4_dnl
###--------------------------------------------------------------------------
### Network layout.
-m4_divert(46)m4_dnl
-## Networks and routing.
-
-defiface $if_untrusted \
- untrusted:172.29.198.0/25
-defvpn $if_vpn safe 172.29.199.128/27 \
- crybaby:172.29.199.129 \
- terror:172.29.199.130
-defiface $if_iodine untrusted:172.29.198.128/28
-defiface $if_its_mz safe:172.29.199.160/30
-defiface $if_its_pi safe:192.168.0.0/24
-defiface $if_trusted \
- trusted:172.29.199.0/26 \
- safe:172.29.199.64/27 \
- untrusted:default
-
-m4_divert(60)m4_dnl
+defnet default untrusted
+
+## Hosts.
+defhost jaguar
+ iface eth0 default
+
+m4_divert(80)m4_dnl
+###--------------------------------------------------------------------------
+### Connection tracking helper modules.
+
+for i in ftp; do
+ modprobe nf_conntrack_$i
+done
+
+m4_divert(80)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
+case $forward in
+ 1)
+
+ ## Only allow these packets if they're not fragmented. (Don't trust safe
+ ## hosts's fragment reassembly to be robust against malicious fragments.)
+ ## There's a hideous bug in iptables 1.4.11.1 which botches the meaning
+ ## of `! -f', so we do the negation using early return from a subchain.
+ clearchain fwd-spec-nofrag
+ run iptables -A fwd-spec-nofrag -j RETURN --fragment
+ run ip6tables -A fwd-spec-nofrag -j RETURN \
+ -m ipv6header --soft --header frag
+ run ip46tables -A FORWARD -j fwd-spec-nofrag
+
+ ## Allow ping from safe/noloop to untrusted networks.
+ run iptables -A fwd-spec-nofrag -j ACCEPT \
+ -p icmp --icmp-type echo-request \
+ -m mark --mark $to_untrusted/$MASK_TO
+ run iptables -A fwd-spec-nofrag -j ACCEPT \
+ -p icmp --icmp-type echo-reply \
+ -m mark --mark $from_untrusted/$MASK_FROM \
+ -m state --state ESTABLISHED
+ run ip6tables -A fwd-spec-nofrag -j ACCEPT \
+ -p icmpv6 --icmpv6-type echo-request \
+ -m mark --mark $to_untrusted/$MASK_TO
+ run ip6tables -A fwd-spec-nofrag -j ACCEPT \
+ -p icmpv6 --icmpv6-type echo-reply \
+ -m mark --mark $from_untrusted/$MASK_FROM \
+ -m state --state ESTABLISHED
+
+ ## Allow SSH from safe/noloop to untrusted networks.
+ run ip46tables -A fwd-spec-nofrag -j ACCEPT \
+ -p tcp --destination-port $port_ssh \
+ -m mark --mark $to_untrusted/$MASK_TO
+ run ip46tables -A fwd-spec-nofrag -j ACCEPT \
+ -p tcp --source-port $port_ssh \
+ -m mark --mark $from_untrusted/$MASK_FROM \
+ -m state --state ESTABLISHED
+
+ ;;
+esac
m4_divert(80)m4_dnl
###--------------------------------------------------------------------------
+### Kill things we don't understand properly.
+###
+### I don't like having to do this, but since I don't know how to do proper
+### multicast filtering, I'm just going to ban it from being forwarded.
+
+errorchain poorly-understood REJECT
+
+## Ban multicast destination addresses in forwarding.
+case $forward in
+ 1)
+ run iptables -A FORWARD -g poorly-understood \
+ -d 224.0.0.0/4
+ run ip6tables -A FORWARD -g poorly-understood \
+ -d ff::/8
+ ;;
+esac
+
+m4_divert(84)m4_dnl
+###--------------------------------------------------------------------------
### Locally-bound packet inspection.
clearchain inbound
-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
+run ip46tables -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
+run ip46tables -A inbound -j forbidden
+run ip46tables -A INPUT -m mark --mark $from_untrusted/$MASK_FROM -g inbound
+
+## Allow responses from the scary outside world into the untrusted net, but
+## don't let untrusted things run services.
+case $forward in
+ 1)
+ run ip46tables -A FORWARD -j ACCEPT \
+ -m mark --mark $to_untrusted/$(( $MASK_FROM | $MASK_TO )) \
+ -m state --state ESTABLISHED,RELATED
+ ;;
+esac
## 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
+for i in $inchains; do
+ run ip46tables -A $i -m mark ! --mark 0/$MASK_MASK -j ACCEPT
done
m4_divert(-1)
~mdw / firewall / blobdiff