+## TCP MSS clamping to help given Demon's sluggish approach to fragmentation-
+## needed errors.
+run ip46tables -t mangle -A FORWARD -o ppp0 -p tcp --tcp-flags SYN,RST SYN \
+ -j TCPMSS --clamp-mss-to-pmtu
+
+## Set up NAT protocol helpers. In particular, SIP needs some special
+## twiddling.
+run modprobe nf_conntrack_sip \
+ ports=5060 \
+ sip_direct_signalling=0 \
+ sip_direct_media=0
+for p in ftp sip h323; do
+ run modprobe nf_nat_$p
+done
+
+## Forbid anything complicated to the NAT address. Be sure to allow ident,
+## though.
+run iptables -A INPUT -d 62.49.204.158 -p tcp -j ACCEPT \
+ -m multiport --destination-ports=113
+run iptables -A INPUT -d 62.49.204.158 ! -p icmp -j REJECT
+