hi! there is strange things,maybe my mistake. I use code in attachment to transmit file by SFTP or FTP. If code compiled to executable , everything is ok(there is other thing that LIST command will be send to server, But i do not send this command), if code compiled to a lib(.so file),when other program call this lib to transmit(SFTP or FTP) file it block at curl_easy_perform interface.I use curl-7.25.0. Everyone who can help me?