Nếu xác thực thành công, một byte NULL được trả về bởi máy chủ, nếu không, giá trị là 1 được trả về trong một chuỗi giao thức rlogin cung cấp nhiều chức năng tương tự như các giao thức Telnet, | 264 Chapter 9 Sniffing If authentication was successful a NULL byte is returned by the server otherwise a value of 1 is returned in addition to an error string. rlogin Port 513 The rlogin protocol provides much the same functionality as the Telnet protocol combined with the authentication mechanism of the rexec protocol with some exceptions. It supports trust relationships which are specified via a file called rhosts in the user s home directory. This file contains a listing of users and the hosts on which they reside who are allowed to log in to the specified account without a password. Authentication is performed instead by trusting that the user is who the remote rlogin client says he or she is. This authentication mechanism works only among UNIX systems and is extremely flawed in many ways therefore it is not widely used on networks today. If a trust relationship does not exist user and password information is still transmitted in plaintext over this protocol in a similar fashion to rexec An ASCII port number specifying a port for the server to connect to to send standard error information. This is a port on the client host that will be awaiting this connection. 0 is specified if this is not desired. This string is NULL terminated. A NULL terminated client username 16 characters long or less. A NULL terminated server username 16 characters long or less. A NULL terminated string consisting of the terminal type and speed. The server then returns a 0 byte to indicate it has received these. If authentication via the automatic trust mechanism fails the connection is then passed onto the login program at which point a login proceeds as it would have if the user had connected via the Telnet service. X11 Port 6000 The X11 Window system uses a magic cookie to perform authorization against clients attempting to connect to a server. A randomly generated 128-bit cookie is sent by X11 clients when connecting to the X Window server. By sniffing this cookie an attacker can .
