Thông báo mã hóa mà không được sử dụng trong ví dụ của chúng tôi, vì vậy mật khẩu FTP có thể được nhìn thấy rõ ràng trong các tập tin nắm bắt trong gói 7 (Hình 6-16).Hình 6-16: Các mật khẩu của csanders người sử dụng có thể được nhìn thấy rõ ràng trong gói này. | Summary You will find that many computer and network problems are not the fault of a particular computer or network but rather the software running on it. In this scenario a weather-tracking program had been installed on Chad s computer causing him to think it was possessed because his web browser s home page changed after every restart. By capturing and examining packets with Wireshark we were able to uncover this program running silently in the background. Examining problems at the packet level makes troubleshooting much easier because so little is hidden. Inbound FTP ftpclientdenied .pcap and ftpserverdenied .pcap In this next scenario let s imagine you have just set up a new FTP server for your company. Clients will be connecting to this FTP server both internally and externally to download and upload large amounts of data. You have set up the FTP server software and have created a generic username and password for use by all employees. However for some reason when you re trying to test the server from a remote machine you are unable to access it through FTP client software. What We Know We know that this server is brand new and has just been set up using Windows Server 2003 with all of the latest updates and service packs installed. We have verified that the FTP software is set up correctly and is active. We have also verified that the client trying to connect to the FTP server is using the appropriate IP address and login credentials. Tapping into the Wire Because this problem involves both a server and a client machine we will take a capture file from both computers. The capture from the client will be done when the FTP client software tries to connect to the server. The capture from the server will be done at the moment the client is trying to connecting to the FTP software. By capturing the files in this fashion we will be able to determine whether the problem originates with the client or the server then we can proceed with further investigation. We ll .
