I have to access a private network with OpenVPN. There is a TFTP service running in that private network. When I try to transfer a file the Windows 7 firewall drops all incoming packets.
The TFTP protocol uses a client port, a server port (69) and a connection port at the server. The client opens a port and sends the TFTP request to the server port. The server opens a new port for the connection and sends the response to the client port. The client recognises the response and the file is transferred using the client port and the connection port.
The firewall drops all packet from the connection port when the communication goes through OpenVPN. When I connect (for test purposes only) directly the same firewall rules allow TFTP communication. The OpenVPN client virtual adapter is categorized as "adapter in public network".
Is there a flaw in the in OpenVPN client causing this problem? Is there a workaround or solution?