Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Protection at a particular protocol layer
Reexamination Certificate
1998-08-03
2001-10-30
Wright, Norman M. (Department: 2131)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Protection at a particular protocol layer
C709S227000
Reexamination Certificate
active
06311275
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for providing simplified access to subscribers of a differentiated computer network. Specifically, the present invention relates to a method for allowing single step log-on access to a network having more than one separate access area, such as a network divided into both public and private areas, where access to public areas is provided by a conventional Network Access Server, or NAS, and access to private areas is provided by a separate Service Selection Gateway, or SSG.
2. Background
Every day, millions of people around the world perform the modern ritual of the network “log-on.” From the user standpoint, the process is simple: if all goes well, after a click of the mouse, and perhaps a few quick keystrokes, the short melodic overture of computers exchanging bits begins, and the intrepid user soon finds himself speeding down the Information Superhighway. Mercifully, the user is usually spared from having to know anything about the technical details of the log-on procedure, which involves multiple servers working in concert to handle the thousands of subscribers who seek access to the network at any given time. The continued success of computer networking technology depends on keeping access easy. As networks have evolved, however, they have begun to differentiate into areas that provide specialized services to selected users. Because of this trend, security and user-authorization protocols are becoming more complicated, often in ways that conflict with the need for easy accessibility.
In order to gain access to a computer network, such as the World-Wide-Web, or the Internet, or a private Intranet network, a user must first dial-in or otherwise connect to a Network Access Server, or NAS. The NAS serves as a gate between the computer network and the user. As a threshold matter, the NAS must authenticate the identity of the subscriber in order to ascertain the nature and scope of the services that it will provide. Of course, if the network is differentiated into public areas that are accessible to all subscribers generally, and private areas that are accessible only to authorized subscribers, then the user's identity is particularly important.
The authentication procedure generally involves another server, herein referred to as an Authentication, Authorization, and Accounting Server, or an AAA Server. The NAS is a client of the AAA Server, which may serve several client NAS's simultaneously. The NAS and the AAA Server communicate with one another according to a standard Internet protocol, such as the Remote Authentication Dial-In User Service (RADIUS) protocol, developed by Livingston Enterprises of Pleasanton, Calif. The description of the authentication procedure that follows is based on the RADIUS protocol.
Typically, the user begins his or her session on the network by first launching a dial-in application on his or her personal computer or PC that prompts the user to enter some form of user identification, like a user-name, and a private password. Such information may also be stored on and automatically provided by the PC. The dial-in application contacts an NAS, for instance, via modem and telephone line, and provides the NAS with the user-entered information. The password data are usually encrypted using methods well-known to those of ordinary skill in the art. The NAS then prepares and sends an “access-request” packet to the AAA Server. The access request packet contains the data entered by the user, as well as additional data identifying the particular NAS client from which the packet was sent.
The AAA Server contains a large database of stored information on the accounts of each subscriber, including user-names, encrypted passwords and configuration information detailing the type of service that is to be provided to each user. When the AAA Server receives an access-request packet from an authorized NAS client, it consults its database of users to find the account entry for the user identified by the information contained in the access-request packet. The account entry will often specify certain requirements that must be met in order for the user to gain access to the network, including information on the clients and ports on the network which the user is allowed to access. An important requirement, of course, is that the password entered by the user match the password specified in the account entry on the AAA database. If the passwords match, and all the other requirements are met, then the AAA Server sends the NAS an “access-accept” packet in response. The access-accept packet contains configuration data that enable the NAS to provide the desired service to the user.
If any requirement is not met, then the AAA Server responds with an “access-reject” packet indicating that the user request in invalid. The access-reject packet may also contain text messages which may be delivered to the user by the NAS. Even if all the requirements are met, the AAA Server may still deny immediate access to the user and instead issue an “access-challenge” packet that prompts the user for new information before access is finally granted.
In order for the network to communicate with the user, the user must be assigned an IP address. User IP addresses are usually assigned dynamically, meaning that a user's IP address can change from session to session. The IP address can be assigned either by the AAA Server, or by the NAS. Once an IP address has been assigned to the user, the user is logged-on to the NAS and can begin his or her session on the network. After logging the user on, the NAS sends an “accounting-start” packet to the AAA Server, containing information regarding, for instance, the time at which the user's session begins, or other administrative and accounting data, that can be stored on the AAA Server's database.
A complication in this scheme arises when the network contains private areas whose access is regulated by a third server, herein referred to as a Service Selection Gateway, or SSG Server. The SSG Server is inserted between the NAS and the AAA Server, and its function is to create secure channels to private areas of the network for authorized users only. In order to access these private areas, an authorized user must somehow log-on to the SSG server as well.
Of course, it is possible to simply inflict upon the user the job of performing a second log-on to the SSG Server after the first log-on to the NAS. This approach is rather cumbersome and inelegant, however, and it requires the use of a separate and largely redundant software application on the user's PC, called a “dashboard.” In order for an authorized user to access private areas of the network through the SSG Server, he or she must first log on to the network using the primary dial-in application, then launch the dashboard, and then log on a second time with the SSG Server.
This solution leaves much to be desired. The torment that comes from staring at pixellated cartoons of tiny telephones on a computer monitor, occasionally for minutes at a time, as a PC attempts to log-on to a heavily-trafficked network, is already an all-too familiar source of frustration to many subscribers of computer network services. Such delays can be caused, for instance, by the large number of access requests that must be handled by the AAA Server. The second log-on to the SSG Server requires a second authorization to access data from a private network and therefore simply adds unnecessarily to the traffic seen by the AAA Server. It also requires the user to re-enter his or her username and password.
Unfortunately, it is not enough to simply pass username and password information from the NAS to the SSG Server. Without the user IP address, the SSG Server has no way to send information from the private areas of the network to the user. While it might be possible to reconfigure the NAS to provide the IP address to the SSG Server directly, or demand that IP addresses are assigned by the AAA Server instead of the NAS
Chu Jie
Dos Santos Maria Alice
Jin Jane Jiaying
Lou Shuxian
Xu Xi
Cisco Technology Inc.
Revak Christopher
Ritchie David B.
Thelen Reid & Priest LLP
Wright Norman M.
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