模块可以连接普通FTP（vsfpd）成功并下载文件，当模块连接同一服务器(显示SSL/TLS加密方式)时，可以成功登录服务器，但当发送PASV命令后，获取到被动端口号去连接服务器却失败了，证书是没有问题的，创建ssl连接时失败了。关闭数据socket后，服务器回复500 OOPS priv_sock_get_result。
连接ftp server软件搭建的ftp服务器，显示ssl连接，可以下载文件，感觉模块功能又是正常的。
所以这可能是什么原因？是vsftpd服务器配置有什么问题?还是ssl库缺少相关文件？
server client TLSv1.2 120 Application Data[Packet size limited during capture]
client server TCP 40 34532 → 21 [ACK] Seq=3984 Ack=4080 Win=46000 Len=0
client server TCP 48 34942 → 28641 [SYN] Seq=0 Win=46080 Len=0 MSS=1460 WS=1 //获取到被动端口号，开始建立数据链路
server client TCP 48 28641 → 34942 [SYN, ACK] Seq=0 Ack=1 Win=62727 Len=0 MSS=1360 WS=128
client server TCP 40 34942 → 28641 [ACK] Seq=1 Ack=1 Win=46080 Len=0
client server TLSv1.2 280 Client Hello[Packet size limited during capture]
client server TLSv1.2 75 Application Data
server client TCP 40 28641 → 34942 [ACK] Seq=1 Ack=241 Win=62592 Len=0
client server TCP 40 34942 → 28641 [FIN, ACK] Seq=241 Ack=1 Win=46080 Len=0 //建立连接失败
server client TCP 40 28641 → 34942 [ACK] Seq=1 Ack=242 Win=62592 Len=0
client server TCP 40 34942 → 28641 [RST] Seq=242 Win=0 Len=0
client server TLSv1.2 77 Application Data
server client TLSv1.2 105 Application Data[Packet size limited during capture]
client server TCP 40 34532 → 21 [ACK] Seq=4021 Ack=4145 Win=46015 Len=0
client server TLSv1.2 100 Application Data
server client TLSv1.2 150 Application Data[Packet size limited during capture]
client server TCP 40 34532 → 21 [ACK] Seq=4081 Ack=4255 Win=45970 Len=0
server client FTP 50 Response: 500 OOPS:
client server TCP 40 34532 → 21 [ACK] Seq=4081 Ack=4265 Win=46070 Len=0
server client FTP 79 Response: error:00000000:lib(0):func(0):reason(0)
client server TCP 40 34532 → 21 [ACK] Seq=4081 Ack=4304 Win=46031 Len=0
server client TCP 42 21 → 34532 [PSH, ACK] Seq=4304 Ack=4081 Win=59520 Len=2 [TCP segment of a reassembled PDU]
client server TCP 40 34532 → 21 [ACK] Seq=4081 Ack=4306 Win=46029 Len=0
client server TLSv1.2 75 Application Data
server client FTP 60 [TCP Previous segment not captured] Response: priv_sock_get_result
client server TCP 40 [TCP Dup ACK 74#1] 34532 → 21 [ACK] Seq=4116 Ack=4306 Win=46029 Len=0
server client TCP 50 [TCP Out-Of-Order] 21 → 34532 [PSH, ACK] Seq=4306 Ack=4081 Win=59520 Len=10
client server TCP 40 34532 → 21 [ACK] Seq=4116 Ack=4336 Win=45999 Len=0
server client TCP 42 21 → 34532 [PSH, ACK] Seq=4336 Ack=4081 Win=59520 Len=2 [TCP segment of a reassembled PDU]
client server TCP 40 34532 → 21 [ACK] Seq=4116 Ack=4338 Win=45997 Len=0
server client TCP 40 21 → 34532 [FIN, ACK] Seq=4338 Ack=4081 Win=59520 Len=0
client server TCP 40 34532 → 21 [ACK] Seq=4116 Ack=4339 Win=46080 Len=0
client server TLSv1.2 71 Encrypted Alert
client server TCP 40 34532 → 21 [FIN, ACK] Seq=4147 Ack=4339 Win=46080 Len=0
server client TCP 40 21 → 34532 [RST] Seq=4306 Win=0 Len=0
server client TCP 40 21 → 34532 [RST] Seq=4306 Win=0 Len=0