7. IPv6

Libra supports IPv6. It can handle both IPv4 and IPv6 addresses of control and data connection.

IPv4 clients can still send PORT and PASV commands to an IPv6 server. Following scenarios are supported:

1. Client sends PORT a,b,c,d,port. It requests to open data connection to an IPv4 address a.b.c.d. Server should convert this address to an IPv4-mapped IPv6 address (::FFFF:a.b.c.d). This is necessary because server's side of data connection belongs to IPv6.
2. Client sends PASV. Server open a data connection in IPv4 family. This is possible only if server's IPv6 address is either ::FFFF:u.v.w.x (IPv4-mapped) or ::0:u.v.w.x (IPv4-compatible).
3. Client sends EPRT 1 a.b.c.d port. Server will behave as in case 1.
4. Client sends EPSV 1. Server will behave as in case 2.