Routing traffic from VPN to LAN

Forums › LAN (ethernet/Wifi/routers/Bluetooth) › Routing traffic from VPN to LAN

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fe31nz

1232 posts

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#1834370 31-Jul-2017 15:02

@freitasm:

Ok, so I have changed the VPN configuration to use the same IP range as the LAN, and it's working as before - it connects, can access the Internet but can't see LAN devices - no ping, no RDP, etc.

I suspect the L2TP protocol implementation is blocking this, because the OpenVPN tab has an option to allow VPN devices to see the LAN devices, which is not in the L2TP tab. Only using L2TP because no client is required on both Android and Windows, but might have to look at the OpenVPN implementation...

For those who mentioned the subnet... Yes, I understand how it won't see each other but thought there would be a way to define a route to get packets from one to another. Since nothing in that front I just change the IP range.

Just using the same IP range is insufficient to get broadcast traffic - you need to have bridging set up between the home subnet and the VPN subnet. In OpenVPN, there are extra options for bridging - maybe L2TP does not support that. I have never used L2TP as I always wanted the best encryption and OpenVPN allows me to do that.

chevrolux

4962 posts

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#1834373 31-Jul-2017 15:09

I suspect the L2TP protocol implementation is blocking this, because the OpenVPN tab has an option to allow VPN devices to see the LAN devices, which is not in the L2TP tab. Only using L2TP because no client is required on both Android and Windows, but might have to look at the OpenVPN implementation

I would take a punt that the option is there so it adds the "push route" stuff to the openVPN config. Or it is creating the appropriate "accept" firewall rules for you.

Did you check your client is set to use the VPN connection as the default route? On your windows client do a "route print" and you should see your VPN interface has a low metric if it is set as default route. Otherwise it gets a high metric in the sort of 200+ range.

Resnick

238 posts

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#1834441 31-Jul-2017 16:26

@freitasm:

I suspect the L2TP protocol implementation is blocking this, because the OpenVPN tab has an option to allow VPN devices to see the LAN devices, which is not in the L2TP tab. Only using L2TP because no client is required on both Android and Windows, but might have to look at the OpenVPN implementation...

I think you're right. Seems you cant push routes to a client in a L2TP tunnel, it needs to be configured client side and my head is hurting reading the microsoft documentation.

It's fairly straightforward to achieve what you want using openvpn though, and there are plenty of free open source clients to choose from.

freitasm

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#1834442 31-Jul-2017 16:28

*sigh*

Might have to get the OpenVPN up and running then. Will be back later.

davidcole

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#1834446 31-Jul-2017 16:39

While not using the same hard are. I have had two l2tp Vpns, one was i into, the other is a ubiquiti USG, both able to access my local network. One as a portion of the regular subnet and the other as a new vlan/subnet.

But I've only ever use iOS as the client, unless that has any bearing on it.

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freitasm

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#1834449 31-Jul-2017 16:48

OpenVPN up and running, connected but still no LAN-side access, only Internet... This is the route table when connected

=======
Interface List
3...34 64 a9 03 c9 ee ......Intel(R) Ethernet Connection (3) I218-LM
14...60 57 18 a5 83 8c ......Microsoft Wi-Fi Direct Virtual Adapter
36...00 ff 97 03 59 4a ......TAP-Windows Adapter V9
5...60 57 18 a5 83 8b ......Intel(R) Dual Band Wireless-AC 7265
1...........................Software Loopback Interface 1
10...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
=======

IPv4 Route Table
=======
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.43.1 192.168.43.252 35
0.0.0.0 128.0.0.0 10.8.0.5 10.8.0.6 35
10.8.0.0 255.255.255.0 10.8.0.5 10.8.0.6 35
10.8.0.1 255.255.255.255 10.8.0.5 10.8.0.6 35
10.8.0.4 255.255.255.252 On-link 10.8.0.6 291
10.8.0.6 255.255.255.255 On-link 10.8.0.6 291
10.8.0.7 255.255.255.255 On-link 10.8.0.6 291
127.0.0.0 255.0.0.0 On-link 127.0.0.1 331
127.0.0.1 255.255.255.255 On-link 127.0.0.1 331
127.255.255.255 255.255.255.255 On-link 127.0.0.1 331
128.0.0.0 128.0.0.0 10.8.0.5 10.8.0.6 35
192.168.2.0 255.255.255.0 10.8.0.5 10.8.0.6 35
192.168.43.0 255.255.255.0 On-link 192.168.43.252 291
192.168.43.252 255.255.255.255 On-link 192.168.43.252 291
192.168.43.255 255.255.255.255 On-link 192.168.43.252 291
203.86.203.11 255.255.255.255 192.168.43.1 192.168.43.252 35
224.0.0.0 240.0.0.0 On-link 127.0.0.1 331
224.0.0.0 240.0.0.0 On-link 10.8.0.6 291
224.0.0.0 240.0.0.0 On-link 192.168.43.252 291
255.255.255.255 255.255.255.255 On-link 127.0.0.1 331
255.255.255.255 255.255.255.255 On-link 10.8.0.6 291
255.255.255.255 255.255.255.255 On-link 192.168.43.252 291

mentalinc

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#1834466 31-Jul-2017 17:07

Are you trying to use IP or hostnames of internal systems?

i.e. is it an internal DNS issue not so much a routing issue?

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freitasm

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#1834468 31-Jul-2017 17:19

Sorted on OpenVPN. LAN still on 192.168.2.0, OpenVPN on 10.8.0.0/24... Created a router firewall rule explicitly allowing traffic from 10.8.0.0 to any 192.168.2.0 destination. On my HP Microserver I created an inbound rule allowing connections from 10.8.0.0 - 10.8.0.254 (note that Windows Firewall wouldn't allow connection if using 10.8.0.0/24).

Now I can access both the router and devices on LAN.

Thanks for all suggestions.