RRAS VPN server with off-subnet address range for clients

Sid 1 Reputation point
2021-07-07T09:14:54.59+00:00

Hello!

I want to implement an RRAS VPN server with off-subnet addresses assigned to the VPN clients.
My problem is that I can ping the VPN clients from the LAN, but I can't ping LAN resources from the VPN Clients.

Here is my setup and how I configured it:
LAN: 192.168.1.0/24
DGW: 192.168.1.254
VPN Client network: 10.41.80.0/21
RRAS server: Single NIC: 192.168.1.6

I configured the RRAS server with VPN and Router roles.
I have created a Static address pool on the RRAS server for the VPN clients 10.41.80.1 - 10.41.87.254
I have disabled all ports, only IKEv2 is used by RAS/Routing; the rest is "Used by none".

On my LAN router (192.168.1.254) I have added one static route: routed the destination network 10.41.80.0/21 to the RRAS server IP 192.168.1.6.
On my LAN router I've allowed the icmp communication between the two network in both directions.

At this point the communication initiated from my LAN to the VPN clients staerted to work, but not the other way.
I can't figure out what am I missing.

Thank you for your input!

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  1. Sid 1 Reputation point
    2021-07-07T14:38:33.637+00:00

    I would like to add some extra information I gathered about the issue:

    • when I try to ping a LAN machine from a VPN client, on my firewall (192.168.1.254) I got the following block message: ICMP reply without request. So the LAN machine tries to reply, but the firewall blocks it. I suspect for some reason the ICMP request comes from the RRAS server 192.168.1.6 (not interacting with my firewall) and the reply goes to the VPN Client's address through my firewall.
    • I am able to query DNS request from a VPN client against my internal DNS server (192.168.1.1) and got a response.
    • I am able to query an NTP resync from my local Windows NTP server (192.168.1.8) and got a response.
    • I am able to ping my firewall LAN IP (192.168.1.254) from a VPN Client and get a response. Still can't ping anything else on the LAN.

  2. Sunny Qi 10,896 Reputation points Microsoft Vendor
    2021-07-13T08:14:16.03+00:00

    Hi,

    Thanks for your update.

    I would suggest you could run command "route print" from VPN client when established a VPN connection to check if there is a route to 192.168.1.0/24.

    If not, I would suggest you add a corresponded route from VPN server since the VPN client obtains route information from VPN server.

    114119-image.png

    Best Regards,
    Sunny

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