为什么不能telnet到FTP得数据端口?
我先打开一个console下的telnet
>>open ftp.host.com 21
>>220 This system is for company related use only. Use may be monitored.
>>USER XXX
>>331 Password required for XXX.
>>PASS XXX
>>230 User bd64421 logged in.
>>SYST
>>215 UNIX Type: L8
>>TYPE I
>>200 Type set to I.
>>PASV
>>227 Entering Passive Mode (169,193,105,89,252,40) 252*256+40=64552
然后我另外打开一个cmd窗口下的telnet
>>open ftp.host.com 64552
显示Connecting To ftp.host.com...Could not open a connection to host on port 64552
: Connect failed
我不熟悉这些协议的东西,请问一下这是为什么?