ttyd (1.5.2) offers the option -i, --interface to define a network interface to bind.
In case 'ttyd login' without the option '-i' is called, 'sockstat -s4' shows the local address '*:7681' so that the socket listens to all interfaces.
In case 'ttyd -i em0 login' is called, sockstat shows the address '192.168.1.144:7681' as expected, so that the socket listens only to that specific interface.
In case 'ttyd -i lo0 login' is called, sockstat shows the address '*:7681' and the socket listens to all interfaces. But in this case I would expect the address '127.0.0.1:7681' and that the socket only listens on the local loopback adapter.