A Teredo server is listening on the remote host.
The remote host is running a Teredo server. Teredo is a protocol for tunneling IPv6 over UDP and is used to enable nodes to obtain IPv6 connectivity even when they are located behind IPv4 NAT devices that have no support for IPv6. A Teredo server is a node that is connected to both IPv4 and IPv6 internets and supports a Teredo tunneling interface over which packets are received.
Limit incoming traffic to this port if desired.