When the FTP server is deployed on the LVS, goftp can't make a data connection.

Consider when A FTP Server is on Linux LVS, which means the VIP(Virtual IP) != RealIP.

`func (ftp *FTP) Pasv() (port int, err error)` only return a port, and `func (ftp *FTP) newConnection(port int) (conn net.Conn, err error)` will combine the `VIP` of LVS and returned `Port` instead of `RealIP` and `Port`.

```Go
func (ftp *FTP) Pasv() (port int, err error) {
var line string
if line, err = ftp.cmd("227", "PASV"); err != nil {
return
}

re, err := regexp.Compile(`\((.*)\)`)

res := re.FindAllStringSubmatch(line, -1)

s := strings.Split(res[0][1], ",")

l1, _ := strconv.Atoi(s[len(s)-2])
l2, _ := strconv.Atoi(s[len(s)-1])

port = l1<<8 + l2

return
}

// open new data connection
func (ftp *FTP) newConnection(port int) (conn net.Conn, err error) {
addr := fmt.Sprintf("%s:%d", strings.Split(ftp.addr, ":")[0], port)

if ftp.debug {
log.Printf("Connecting to %s\n", addr)
}

if conn, err = net.Dial("tcp", addr); err != nil {
return
}

if ftp.tlsconfig != nil {
conn = tls.Client(conn, ftp.tlsconfig)
}

return
}
```

I suggest use `func (ftp *FTP) Pasv() (host string, port int, err error) ` and `func (ftp *FTP) newConnection(host string, port int) (conn net.Conn, err error)`

If you want it , I will push a request pull.