SSDP (Multicast) over VPN (PPTP)

[hannes085]

Hello everybody,

I set up a Cisco RV180 VPN Router with VPN (PPTP) enabled. Everything works fine so far. When i'm connected to the VPN from a remote Network with an iPhone, iPad or Notebook i'm able to ping all devices and to reach the setup pages with a browser.

But I have an UPnP Application running which sends out SSDP (Multicast) Packets to 239.255.255.250:1900 to find compatible devices.

My Problem is that I can't get that Multicast stuff workiung over VPN. I know that basically Multicast Packets are not submitted over a VPN - but I think there has to be a workaround for me to get that UPnP thing working over VPN.

Maybe somebody has an idea for me. Thanks!

[Mario Grozdanovic]

Hi hannes085,

When your UPnP application connects and tries its thing, are you able to check the VPN routers logs to see what is being blocked or if it sees any traffic from that application? It looks like a GUI device so im not sure if it would get that granular.

One thing you may try is to disable the firewall and/or any restrictions on the VPN tunnel and then test again. 

-Mario

[hannes085]

I checked the Firewall log but there seems nothing to be blocked at the time when the Client tries to multicast. I also checked the traffic using wireshark, but there seems to be no traffic from the client on the VPN side. On the client side I can see the outgoing SSDP packets.

I just noticed that the VPN connected client has an IP Adress from the VPN reserved range but another subnet mask. The Subnet of my network is 255.255.255.0 and the VPN connected Client is in the 255.255.255.255 Subnet. Can this be a reason for the connection not to work?

[Mario Grozdanovic]

The 255.255.255.255 address for your client is typical. Can you draw a quick diagram on where you captured your packets on both sides?