To^i du`ng ethereal kie^?m tra thi` tha^'y VLTK du`ng passive FTP dde^? update, Lo^~i pha't sinh ta.i package PORT cu?a Client khi du`ng qua tu+o+`ng lu+?a. So sa'nh:
-- Khi kho^ng co' tu+o+`ng lu+?a: Src: client, Dest: Upd server port: 4712 to port: 21 Request command: PORT Request arg: 192,168,200,64,18,105 Active IP address: 192.168.200.64 Active port 4713 Src: Upd Server, Dest: client port 21 to port 4712 Response code: Command okay (200) Response arg: PORT command successful. Consider using PASV. -- Khi co' tu+o+`ng lu+?a Src: client, Dest: Upd server port: 2223 to port: 21 Request command: PORT Request arg: 192,168,100,126,8,176 Active IP address: 192.168.100.126 Active port 2224 Src: Upd Server, Dest: client port 21 to port 2223 Response code: Syntax error, command unrecognized (500) Response arg: Illegal PORT command Xin ca'c ba'c va`i ve'. DDa ta. Tri
