feat: automated iptables setup for ssh + i2np + icmp pings

docker-compose.yml

@@ -4,10 +4,11 @@ services:
   i2p:
     image: geti2p/i2p
     container_name: i2p
+    restart: unless-stopped
     ports:
-      # Automatically exposed to localhost: 4444-4445/tcp, 6668/tcp, 7654/tcp, 7656-7660/tcp
-      - ${EXT_PORT:?host port must be manually set}:12345/tcp
-      - ${EXT_PORT:?host port must be manually set}:12345/udp
+      # Automatically exposed locally: 4444-4445/tcp, 6668/tcp, 7654/tcp, 7656-7660/tcp
+      - ${EXT_PORT}:${EXT_PORT}/tcp
+      - ${EXT_PORT}:${EXT_PORT}/udp
     volumes:
       - ${PWD}/i2pconfig:/i2p/.i2p:rw # Mandatory configs
       - ${PWD}/i2ptorrents:/i2psnark:rw # Torrenting support

iptables.sh

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+
+# Clears the old iptables rules and sets new ones to only allow SSH & I2NP traffic (+ ICMP pings)
+
+
+sudo apt update && sudo apt install iptables iptables-persistent -y
+
+read -p "[?] Confirm the deletion of old iptables rules: " -n 1 -r
+! [[ "$REPLY" =~ ^[Yy]$ ]] && echo -e "\n[!] Aborting..." && exit 0
+
+! [ -f ".env" ] && echo "[!] The .env file not found, aborting..." && exit 1
+
+set -a
+source .env
+set +a
+
+[ -z ${EXT_PORT} ] && echo "[!] EXT_PORT is not configured, aborting..." && exit 1
+
+# Clear all old rules (IPv4)
+sudo iptables -P INPUT ACCEPT
+sudo iptables -P FORWARD ACCEPT
+sudo iptables -P OUTPUT ACCEPT
+sudo iptables -t nat -F
+sudo iptables -t mangle -F
+sudo iptables -F
+sudo iptables -X
+
+# Clear all old rules (IPv6)
+sudo ip6tables -P INPUT ACCEPT
+sudo ip6tables -P FORWARD ACCEPT
+sudo ip6tables -P OUTPUT ACCEPT
+sudo ip6tables -t nat -F
+sudo ip6tables -t mangle -F
+sudo ip6tables -F
+sudo ip6tables -X
+
+# Allow all incoming SSH traffic (tcp:22)
+sudo iptables -A INPUT -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
+sudo ip6tables -A INPUT -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
+
+# Allow all I2NP traffic (tcp:$EXT_PORT, udp:$EXT_PORT)
+# Not using `--state NEW,ESTABLISHED` guarantees that **all** incoming and outgoing traffic is let through
+sudo iptables -A INPUT -p tcp --dport $EXT_PORT -j ACCEPT
+sudo ip6tables -A INPUT -p tcp --dport $EXT_PORT -j ACCEPT
+sudo iptables -A INPUT -p udp --dport $EXT_PORT -j ACCEPT
+sudo ip6tables -A INPUT -p udp --dport $EXT_PORT -j ACCEPT
+
+# Allow all incoming ICMP echo requests (pings)
+sudo iptables -A INPUT -p icmp --icmp-type echo-request -m state --state NEW,ESTABLISHED -j ACCEPT
+
+# Allow all ICMP traffic via IPv6 (ICMPv6 is essential for IPv6 to function)
+sudo ip6tables -A INPUT -p ipv6-icmp -j ACCEPT
+
+# Allow all related and established incoming traffic (i.e. allow responses to outgoing requests initiated by the local system)
+sudo iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
+sudo ip6tables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
+
+# Reject all other incoming traffic with DROP (DROP doesn't provide information about 
+# the host configuration to potential attackers like REJECT would, which is why it's used)
+sudo iptables -A INPUT -j DROP
+sudo ip6tables -A INPUT -j DROP
+
+# Persist changes
+sudo iptables-save | sudo tee /etc/iptables/rules.v4
+sudo ip6tables-save | sudo tee /etc/iptables/rules.v6