X-Git-Url: https://git.distorted.org.uk/~mdw/firewall/blobdiff_plain/0291d6d55d3dc38a12d61abc007dda5cc3aa5110..429f4314d0d1be69f7500cf7f97671595804fdd0:/local.m4

diff --git a/local.m4 b/local.m4
index 5e27449..4123a77 100644
--- a/local.m4
+++ b/local.m4
@@ -1,4 +1,4 @@
-### -*-m4-*-
+### -*-sh-*-
 ###
 ### Local firewall configuration
 ###
@@ -51,6 +51,9 @@ defiface $if_trusted \
 	safe:172.29.199.64/27 \
 	untrusted:default
 
+## Default NTP servers.
+ntp_servers="158.152.1.76 158.152.1.204 194.159.253.2 195.173.57.232"
+
 m4_divert(60)m4_dnl
 ###--------------------------------------------------------------------------
 ### Special forwarding exemptions.
@@ -91,6 +94,21 @@ run ip6tables -A FORWARD -j ACCEPT \
 	-m mark --mark $from_untrusted/$MASK_FROM \
 	-m state --state ESTABLISHED
 
+m4_divert(60)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.
+run iptables -A FORWARD -g poorly-understood \
+	-d 224.0.0.0/4
+run ip6tables -A FORWARD -g poorly-understood \
+	-d ff::/8
+
 m4_divert(80)m4_dnl
 ###--------------------------------------------------------------------------
 ### Locally-bound packet inspection.
@@ -110,6 +128,13 @@ run iptables -A inbound -j ACCEPT \
 	-s 172.29.198.0/23 \
 	-p udp --source-port $port_bootpc --destination-port $port_bootps
 
+## Incoming broadcast multicast on a network interface associated with the
+## trusted network is OK, since it must have originated there (or been
+## forwarded, but we don't do that yet).
+run iptables -A inbound -j ACCEPT \
+	-s 0.0.0.0 -d 224.0.0.0/24 \
+	-i $if_trusted
+
 ## Allow incoming ping.  This is the only ICMP left.
 run ip46tables -A inbound -j ACCEPT -p icmp