How to add persistent route for 2 VPN connections when interface # varies?

Question

I need to configure split tunnelling with persistent routes for 2 VPN connections on the same computer as the user needs to connect to 2 different corporate servers at the same time. I have a problem though as the VPN interface # varies in some instances and thus the routes are not being used properly and consistently when the VPN connections are established.

Here are the routes I added:

route add -p 192.168.10.0 mask 255.255.255.0 0.0.0.0 IF 24
route add -p 10.8.18.0 mask 255.255.255.0 0.0.0.0 IF 23

24 being the VPN interface number for VPN 1, 23 for VPN 2. See below.

C:\Windows\system32>route print
===========================================================================
Interface List
 24...........................VPN 1
 23...........................VPN 2
 17...da d1 cb e2 2c ad ......Apple Mobile Device Ethernet
  1...........................Software Loopback Interface 1
 12...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
 13...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
 14...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2
 16...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3
===========================================================================

If I add the routes after connecting to the VPNs then it all works fine but if I disconnect the two VPN connections and then reconnect them in a different order, then the routes are messed up and obviously I can't access the remote networks.

Is there any another way to make the route use a specific interface persistently?

Solution

When multiple VPNs connect in random order, their interface IDs change. Therefor the normal ROUTE -P ADD 10.0.0.0 MASK 255.255.0.0 10.0.0.1 IF 42 does not work. The next time the VPN connects it might have a different interface number.

Powershell has a cmdlet available that adds routes on VPN connection and removes them again when the VPN is disconnected: Add-VpnConnectionRoute. It works without having to specify the interface ID.

The basic syntax is like this:

Add-VpnConnectionRoute -ConnectionName "VPN Connection Name" -DestinationPrefix 10.0.0.0/16

After entering this command, the routes will be created/removed automatically on connection/disconnection of the VPN.

Comments

[Hanuman]

This is not viable. The VPN connections are made from an off site laptop.

[Hanuman]

Anyone else has some suggestions?

[Hanuman]

I tried PowerShell. It returns the following error: PS C:\WINDOWS\system32> Add-VpnConnectionRoute -ConnectionName "VPN 1" -DestinationPrefix "192.168.10.0/16" Add-VpnConnectionRoute : Invalid parameter DestinationPrefix 192.168.10.0/16. : The parameter is incorrect. At line:1 char:1 + Add-VpnConnectionRoute -ConnectionName "VPN 1" -DestinationPref ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : InvalidArgument: (VPN 1:root/Microsoft/...ConnectionRoute) [Add-VpnConnectionRoute], CimExceptio n + FullyQualifiedErrorId : WIN32 87,Add-VpnConnectionRoute

[ErikvO]

I think the IP range you provided might be invalid: 192.168.10.0/16. I think it should either be 192.168.0.0/16 or 192.168.10.0/24.

[Hanuman]

Yeah that was dumb of me. It works now. Thank you.

[Tilo]

how to do in powershell similar as route PRINT?

[user3513074]

Ok any reference to "Add-VPNConnectionRoute" in Powershell is Windows 10 only. That command is not supported in Windows 7, so if you're running Windows 7 we're still screwed until someone finds a way..

[ErikvO]

Actually, according to the technet link I provided it works from Windows 8.1 and up, but you're right: Windows 7 (and 8.0) users still have a problem.

[lese]

@Tilo : similar to route print (Get-VpnConnection -Name $Name -AllUserConnection).routes