Network interface

On machines with multiple network interfaces that are connected to multiple networks, there are situations where you can decide which network interface you would prefer the outgoing network traffic to use. Or which originating IP address (out of the multiple ones you have) to use in the communication.
Tell curl which network interface, which IP address or even host name that you would like to "bind" your local end of the communication to, with the --interface option:
curl --interface eth1
curl --interface
curl --interface machine2