connection destination, hoping this to help ftpd's behavior with
scoped IPv6 addresses.
I'm not sure if it is the right way, but it is the best way available to us.
LPRT or EPRT command gives no information about which interface (or scope)
to be used for new data connection.
ftp(1): On data connection establishment, warn if scoped address is used.
If peer (ftp daemon) does not handle scoped address, data connection
may not work right.
This seems to be sort of protocol spec hole, not implementation issue.
b59b162709