Peer authentication is checked during the handshake. For client connections, we simply
do not add a peer to the map if the authentication fails.
On the server side instead, we need to keep track of in progress handshakes until we have
authenticated reliably a node by its id.
FIXME: In addition, until a better solution is implemented, a correspondence between addresses
and ids is needed to handle subscriptions. However, this is subject to ip spoofing
attacks and should not be used in an open network.