IP Routing with Namespaces

ip_routing_ns.sh

#!/usr/bin/env bash

set -ex

BRIDGE_NAME="br0"
BRIDGE_IP="192.168.92.1"

setup_bridge() {
    echo "Setting up bridge $BRIDGE_NAME"
    ip link add name $BRIDGE_NAME type bridge
    ip addr add $BRIDGE_IP/24 dev $BRIDGE_NAME
    ip link set $BRIDGE_NAME up
}

create_namespace() {
    local ns_name=$1
    local veth=$2
    local br_veth=$3
    local ip_addr=$4
    local table_id=$5
    local external_gateway=$6

    echo "Creating namespace: $ns_name"
    ip netns add "$ns_name"

    echo "Setting up veth pair: $veth <-> $br_veth"
    ip link add "$veth" type veth peer name "$br_veth"

    ip link set "$veth" netns "$ns_name"
    ip link set "$br_veth" master $BRIDGE_NAME

    echo "Configuring namespace $ns_name with IP: $ip_addr"
    ip netns exec "$ns_name" ip addr add "$ip_addr/24" dev "$veth"
    ip netns exec "$ns_name" ip link set "$veth" up
    ip netns exec "$ns_name" ip link set lo up

    ip link set "$br_veth" up

    echo "Setting up routing for $ns_name"
    ip netns exec "$ns_name" ip route add default via $BRIDGE_IP dev "$veth"
    
    # Add the specific route on the host
    ip route add 192.168.91.0/24 via "$external_gateway" dev eth0 table "$table_id"
    ip rule add from "$ip_addr" table "$table_id"

    echo "Namespace $ns_name configured successfully!"
}

enable_nat() {
    echo "Enabling NAT"
    iptables -t nat -A POSTROUTING -s 192.168.92.0/24 -o eth0 -j MASQUERADE
    iptables -A FORWARD -i $BRIDGE_NAME -o eth0 -j ACCEPT
    iptables -A FORWARD -i eth0 -o $BRIDGE_NAME -j ACCEPT
}

# Main script execution
echo "Setting up network namespaces for Tesla inverters..."

sysctl -w net.ipv4.ip_forward=1
sysctl -w net.ipv4.conf.all.rp_filter=0
sysctl -w net.ipv4.conf.default.rp_filter=0

setup_bridge

ip_addresses=("192.168.1.67" "192.168.1.250")

counter=1
for ip in ${ip_addresses[@]}
do
    ip_suffix=$((99 + counter))
    table_id=$((ip_suffix))
    create_namespace "inverter${counter}" "veth${counter}" "br-veth${counter}" "192.168.92.${ip_suffix}" $table_id $ip
    counter=$((counter + 1))
done

# Namespace 1: inverter1
#create_namespace "inverter1" "veth1" "br-veth1" "192.168.92.100" 101 "192.168.1.250"

# Namespace 2: inverter2
#create_namespace "inverter2" "veth2" "br-veth2" "192.168.92.101" 102 "192.168.1.67"

enable_nat

echo "Network namespaces for Tesla inverters have been set up successfully!"