Incoming and outgoing ICMPv6 "Echo Request" and "Echo Reply" exceptions must be enabled. While Symmetric NATs are popular in hotspots and Restricted NATs are popular in homes, communication between the two has the potential to fault on the side of the Restricted NAT. If this condition is not met, the potential for scenarios to encounter compatibility issues involving communication between certain NAT types is introduced specifically between Symmetric NATs and Restricted NATs. The firewall permits the system to send and receive UDP/IPv4 packets to UDP port 1900 on the local subnet as this allows UPnP discovery traffic to flow and has the potential to improve connectivity rates. The FwpmSystemPortsGet0 function should be implemented in place of the now deprecated GetTeredoPort or NotifyTeredoPortChange functions. The firewall must retrieve dynamic UDP ports used by Teredo service on the local machine by calling the FwpmSystemPortsGet0 function relevant ports are of type FWPM_SYSTEM_PORT_TEREDO.
UDP Port 3544 must be open to ensure that Teredo clients can successfully communicate with the Teredo server. The client firewall must allow resolution of. The following firewall configurations are required to ensure smooth interoperation between a firewall and Teredo: To enable this type of scenario, the firewall exceptions detailed in this document must be implemented. For an application to receive Teredo traffic, the application must be permitted to receive IPv6 traffic in the host firewall, and the application is required to set the socket option IPV6_PROTECTION_LEVEL to 'PROTECTION_LEVEL_UNRESTRICTED'.