This is only for incoming echo requests and outgoing echo replies. Currently, incoming requests / outgoing replies are allowed to/from a B4 that controls port 0. That is a superset of all B4s that have full IPs. We should only allow ping to a B4 that has a full IP, because it's usually assumed that if you can ping an IPv4, that all ports on that IPv4 are on the same host.
This is only for incoming echo requests and outgoing echo replies. Currently, incoming requests / outgoing replies are allowed to/from a B4 that controls port 0. That is a superset of all B4s that have full IPs. We should only allow ping to a B4 that has a full IP, because it's usually assumed that if you can ping an IPv4, that all ports on that IPv4 are on the same host.