The motivation is quite trivial. I have two interfaces, one for Internet connections and one for IPTV connections. Of course, the internet connection is by default. When I used retina to connect to my IPTV, it connected through my Internet interface, which was unexpected. So I have to bind to an interface for the connection. This works exactly like curl -I or ping -I, and it also affects the UDP connection.
The motivation is quite trivial. I have two interfaces, one for Internet connections and one for IPTV connections. Of course, the internet connection is by default. When I used retina to connect to my IPTV, it connected through my Internet interface, which was unexpected. So I have to bind to an interface for the connection. This works exactly like
curl -Iorping -I, and it also affects the UDP connection.