Multicast using openVPN

[andnan]

As part of my masters research, I need to send a multicast packet to an arbituary number of client machines ( embedded hardware devices actually that I can install LINUX on) with security for access to a resource.

I'm thinking this will work.
1. Clients automatically join an openVPN network upon power up.
2. After the Client has joined the network, it registers with an application (Lets call him BOB) that is needed for my reserch work over the secure VPN.
3. Periodically, BOB looks at the number of clients that are registerd and divides up a resource(the amount of resource available chanes randomly over time), allocating it to the clients until it is consumed. BOB then uses a multicast protocol ( UDP? ) to send a command to all registered clients.
4. Each client receives the packet and parses the data. Within the packet is information that the client can use to determine if he has access to the resource.

So, can I do this with openVPN?

[krzee]

yes, possibly 3 ways:

• you want a tap bridge to do it easily (but less secure due to sharing the entire layer2 (think arp poisoning)
  you can test using tap without a bridge... this may work since mcast is actually IP traffic
  otherwise you could use TUN with some sort of multicast relay

[esumit]

Andan, Did you try to work on it ? Does it work over TAP ? and Why exactly it doesn't work over TUN ?