diff --git a/entrypoint.sh b/entrypoint.sh
index 8ba3c7b..2ddbc06 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -8,5 +8,9 @@ sysctl -w net.ipv4.ip_forward=1
 # configure firewall
 iptables -t nat -A POSTROUTING -s 10.99.99.0/24 ! -d 10.99.99.0/24 -j MASQUERADE
 iptables -A FORWARD -s 10.99.99.0/24 -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j TCPMSS --set-mss 1356
+iptables -A INPUT -i ppp0 -j ACCEPT
+iptables -A OUTPUT -o ppp0 -j ACCEPT
+iptables -A FORWARD -i ppp0 -j ACCEPT
+iptables -A FORWARD -o ppp0 -j ACCEPT
 
 exec "$@"