Bind Addresses
When you add a port, you can specify an IP address to bind to the port. Specify a bind address in the following situations:
Your machine has multiple IP addresses, and you want the port to use a specific address.
You want multiple ports to use the same port number. In this case, each port must specify a different bind address. For example, if port 7777 is associated with a bind address, you cannot add another port 7777 that does not specify a bind address.
If you do not specify a bind address, the port listens to all network interfaces.