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Mac Network Route Switcher

macnetwork

There is a neat tool called SwitchHosts that lets you easily configure hosts on your mac. But what about network routes? What if you want to send specific traffic to different interfaces?

When you use a VPN with split tunneling, it can do some of that automatically… but you can’t tweak it.

I found a script somewhere in the internet and tweaked it a bit to let you do this.

There are a few great uses!

  1. Split your work and home internet traffic
  2. Run a vpn router for streaming separately than a local wifi
  3. Split traffic between several wifi connections
  4. … you get the point or you wouldn’t be here :)

You can tweak this to add in more “special” interfaces as needed.

import os
import subprocess
import sys

# a couple useful commands:
#
# list networks: networksetup -listallhardwareports
# List routes: netstat -nr
# netstat -nrf inet
# test route: route get 10.1.2.197

# This is gonna be your primary/default interface
WIRELESS_INTERFACE = {
    "interface": 'en0',
    "router": "192.168.1.1"
    }

# This is where you wanna send "special" traffic.
TUNNEL_INTERFACE = {
    "interface":'en6',
    "router": "123.456.789.012"
    }


# Ranges of IP's that should go to your "special" interface
VPN_NETS = [
    '10.1.2.0/24',
    '10.1.3.0/24',
]

# List of IP addresses that should go to your "special" interface
VPN_HOSTS = [
    '123.45.67.89',
]

def split_vpn_traffic():
    if os.getuid() != 0:
        sys.exit("Please, run this command with sudo.")

    print("Resetting routes with gateway " + WIRELESS_INTERFACE["router"])
    subprocess.call(
        ("route", "-n", "delete", "default", "-ifscope", WIRELESS_INTERFACE["interface"])
    )
    subprocess.call(
        ("route", "-n", "delete", "-net", "default", "-interface", TUNNEL_INTERFACE["interface"])
    )
    subprocess.call(
        ("route", "-n", "delete", "-net", "default",TUNNEL_INTERFACE["router"])
    )


    subprocess.call(("route","flush"))
    subprocess.call(("route", "-n", "add", "-net", "default", WIRELESS_INTERFACE["router"]))

    print("\nAdding routes for addresses which should go through VPN.")
    for addr in VPN_NETS:
        subprocess.call(
            ("route", "-n", "add", "-net", addr, TUNNEL_INTERFACE["router"])
        )
    for addr in VPN_HOSTS:
        subprocess.call(
            ("route", "-n", "add", "-host", addr, TUNNEL_INTERFACE["router"])
        )

if __name__ == "__main__":
    split_vpn_traffic()

Save it as split_host.py, and then run it with sudo python split_host.py. Routes are reset when you reboot your mac so you will need to run this after each reboot. You could setup a job to run this script when your computer boots with automator.

Also note that the first route flush call can take a minute to complete.

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