Added ipnat container

ipnat/build/Dockerfile

@@ -0,0 +1,33 @@
+FROM debian:bullseye
+
+USER root
+
+# Install all packages
+ENV DEBIAN_FRONTEND noninteractive
+RUN apt-get update --yes && \
+	apt-get upgrade --yes && \
+	apt-get install --yes --no-install-recommends \
+	bash \
+	#tini \
+	locales \
+	iptables \
+	&& \
+	# Clean up and generate locales
+	apt-get clean && rm -rf /var/lib/apt/lists/* && \
+	echo "en_US.UTF-8 UTF-8" > /etc/locale.gen && \
+	locale-gen
+
+
+# Requires cap-add NET_ADMIN NET_RAW
+
+EXPOSE 33
+EXPOSE 993
+EXPOSE 587
+
+COPY start.sh /start.sh
+COPY iptables.sh /iptables.sh
+
+#ENTRYPOINT ["tini", "-g", "--"]
+ENTRYPOINT ["bash"]
+CMD ["start.sh"]
+

ipnat/build/iptables.sh

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+nat () {
+    # All traffic to $THIS_PORT on this container
+    # will be redirected to $THAT_PORT on $THAT_IP
+    $THAT_IP=$1
+    THIS_PORT=$2
+    THAT_PORT=$3
+
+    # Accept forward incoming traffic
+    iptables -I FORWARD -d $FWD_IP -m tcp -p tcp --dport $THAT_PORT -j ACCEPT
+
+    # Accept forward return traffic
+    iptables -I FORWARD -s $FWD_IP -m tcp -p tcp --sport $THAT_PORT -j ACCEPT
+
+    # Redirect packets to remote
+    iptables -t nat -I PREROUTING -m tcp -p tcp --dport $THIS_PORT -j DNAT --to-destination $THAT_IP:$THAT_PORT
+}
+
+NAT_IP=10.143.0.20
+nat $NAT_IP 33 10013
+nat $NAT_IP 993 10015
+nat $NAT_IP 587 10016
+
+
+
+
+
+# Include this line ONCE, at the end.
+iptables -t nat -I POSTROUTING -d $FWD_IP -j MASQUERADE

ipnat/build/start.sh

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+#!/bin/bash
+
+touch /var/log/iptables.log
+
+bash /iptables.sh
+
+iptables -A INPUT -j LOG --log-prefix "[I]iptables: "
+iptables -A OUTPUT -j LOG --log-prefix "[O]iptables: "
+iptables -A FORWARD -j LOG --log-prefix "[F]iptables: "
+
+tail -f /var/log/iptables.log

ipnat/docker-compose.yml

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+version: "2"
+
+services:
+  ipnat:
+    build: ./build
+    container_name: ipnat
+    restart: unless-stopped
+
+    ports:
+      - "10010:10010"
+
+    cap_add:
+     - NET_ADMIN
+     - NET_RAW