Struct sockaddr_in addr.
Int data_sockfd conn_sock, port;

Conn_sock=socket (PF_INET SOCK_STREAM, 0).
If (conn_sock==1)
{
Printf ("====% d connect is the error \ n ", __LINE__);
return ;
}

Memset ((char *) & amp; Addr, 0, sizeof (addr));
Addr. Sin_family=AF_INET;
Addr. Sin_addr. S_addr=htonl (INADDR_ANY);
//addr. Sin_port=htons (20);

If (bind (conn_sock, (struct sockaddr *) & amp; Addr, sizeof (addr))==1) {
Close (conn_sock);
Printf ("====% d connect is the error \ n ", __LINE__);
return ;
}

If (listen (conn_sock, SOMAXCONN)==1) {
Close (conn_sock);
Printf ("====% d connect is the error \ n ", __LINE__);
return ;
}

Len=sizeof (struct sockaddr);
If (getsockname (conn_sock, (struct sockaddr *) & amp; Addr, (socklen_t *) & amp; Len)==1)
{
Close (conn_sock);
return ;
}
Port=addr. Sin_port;

If (getsockname (control_sockfd, (struct sockaddr *) & amp; Addr, (socklen_t *) & amp; Len)==1)//when the created socket
{
Close (conn_sock);
return ;
}

Memset (com, 0 ();
Memset (recvline, 0, FTP_DATE_MAXSIZE);


Sprintf (com, "PORT % d, % d, % d, % d, % d, % d \ r \ n",
Addr. Sin_addr. S_addr & amp; 0 x000000ff,
(addr. Sin_addr. S_addr & amp; 0 x0000ff00) & gt;> 8,
(addr. Sin_addr. S_addr & amp; 0 x00ff0000) & gt;> 16,
(addr. Sin_addr. S_addr & amp; 0 xff000000) & gt;> 24,
Port> 8, port& 0 XFF);
if(! Ftp_socket_command (com, "200", recvline))
return ;//send command, receive the server message 200 PORT command successful. Consider using PASV,


Struct sockaddr_in peerServer;
Int acceptfd=1;
Socklen_t len_1=sizeof (peerServer);
Data_sockfd=accept (conn_sock, (struct sockaddr *) & amp; PeerServer, & amp; Len_1);//has been blocked
If (1==data_sockfd)
{
Printf ("====% d connect is the error \ n ", __LINE__);
Return cur_fg_dir;
}