Forwarding incoming request coming on X interface to Y interface for list of ports at once.

configure_iptable.sh

#!/bin/bash

# Define the destination IP
DEST_IP="100.124.186.54" # Replace it with your tailscale / Wireguard ip of the destination server

# Define the network interfaces
INTERFACE_IN="eth0"
INTERFACE_OUT="tailscale0" # Replace with your interfce name of tailscale / wireguard interface name.

# Define the ports
PORTS=(80 443)

# Loop over the ports and apply iptables rules
for PORT in "${PORTS[@]}"; do
    # Allow incoming traffic on the specified port
    iptables -A INPUT -p tcp --dport $PORT -j ACCEPT

    # Forward traffic between interfaces for the specified port
    iptables -A FORWARD -i $INTERFACE_IN -o $INTERFACE_OUT -p tcp --dport $PORT -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    iptables -A FORWARD -i $INTERFACE_OUT -o $INTERFACE_IN -p tcp --sport $PORT -m conntrack --ctstate ESTABLISHED -j ACCEPT

    # PREROUTING rule for the specified port
    iptables -t nat -A PREROUTING -i $INTERFACE_IN -p tcp --dport $PORT -j DNAT --to-destination $DEST_IP

    # POSTROUTING rule for the specified port
    iptables -t nat -A POSTROUTING -o $INTERFACE_IN -p tcp --dport $PORT -j MASQUERADE
done

echo "iptables rules have been successfully added for ports: ${PORTS[@]}"