Truyền thông này là tổng hợp độc đáo trong cột Thông tin của cửa sổ Danh sách gói, mặc dù cửa sổ chỉ cho một bản tóm tắt rất ngắn gọn về các nội dung gói tin. Nếu bạn muốn đào sâu hơn một chút, bạn có thể mở rộng phần FTP trong khung Packet Thông tin chi tiết. | This communication is summed up nicely in the Info column of the Packet List pane though that window only gives a very brief summary of the packet contents. If you want to dig a little deeper you can expand the FTP section in the Packet Details pane. Notice that encryption is not used in our example so the FTP password can be seen clearly in the capture file in packet 7 Figure 6-16 . s Frame 7 65 byres on wire 65 byres captured s Ethernet II src HonHaiPr_6e 8b 24 00 16 ce 6e 8b 24 Dst Asustekc_40 76 ef OO 15 f2 40 76 ef H internet Protocol src Dst s Transmission control Protocol src Port 1137 1137 Dst Port ftp 21 seq 16 Ack 68 Len 11 File Transfer Protocol FTP PASS echo r n Request command PASS Request arg echo Figure Ố-1Ố The password of the user csanders can be seen clearly in this packet. A connecting client uses a list of commands to interact with an FTP server. These range from viewing the contents of a directory traversing a directory downloading or deleting a file and so on. For a complete list of the available commands visible in an FTP packet see RFC 959. Let s look at a few FTP commands used in our example file beginning with packet 15 shown in Figure 6-17. Figure Ố-17 Packet 15 shows the PWD command being issued to the server. CWD Command As you can see packet 15 shows a CWD command being sent from the client to the server. CWD stands for change working directory and this command is invoked every time you tell an FTP client to move to a different directory on the server. Notice in this example that the CWD command includes requests to change the working directory to which is the root directory of the FTP server. When you first log into an FTP server the CWD command is issued to change to the root directory . Once the server receives this CWD command it changes to the root directory and tells the client that is now the current working directory. SIZE Command The next command is the SIZE command shown
