Analysis and implementation method of Microsoft Agent service System _ Proxy Server

Absrtact: Based on practical application development experience, this paper introduces the Microsoft Agent Service system and its implementation process in detail. The working mechanism of the system is deeply analyzed. To facilitate the reader to establish and maintain an intranet or local Area Network agent system, the correct understanding and understanding of the Microsoft Agent Service system, and effectively implemented.

Keyword Proxy server Internet proxy network in an intranet or some local area network, the use of Microsoft Agent service system, so that LAN users through a proxy server to access the Internet network, not only save the IP address, but also save the networking equipment. In the area of internal information security, the agent system is able to deny external Internet users access to intranet network resources. Especially in the system with firewall installed, the proxy server runs above the firewall, and realizes the exchange of information inside and outside effectively. In terms of performance, almost as directly as the workstation on the Internet, support any Internet client applications, providing a variety of internet services. Therefore, the agency service system is a kind of economical and effective networking scheme.

One, Microsoft Proxy server running Microsoft Proxy Server is a powerful system that includes Web proxy servers, Winsock proxy servers, and SOCKS proxy servers. The WEB proxy server, which is compatible with the Cren communication standard, consists of a filter and an application that combines with the IIS Web server to accept client service requests through the TCP80 port. The filter determines whether the HTTP request received is a proxy format or a standard format. If it is a standard format, it is handled by the local WWW server and, if it is a proxy format, by the agent application. The proxy application first looks in the proxy cache area, if the data already exists and the TTL is still in effect, pulls the data out of the cache, and if it does not, connects the remote target server and obtains the data. Whether a proxy server obtains information from a buffer or from an Internet remote server, it sends the information to the requestor via the HTTP protocol on port 80th. Winsock Proxy completes the client request by intercepting the application's Winsock call. To do this, the Winsock Proxy client software must be installed on the client computer to update the original Winsock dynamic link library of the client. Once an Internet application makes a Winsock call to a new dynamic link library, it communicates with the Winsock Proxy Server on port 1745th. The Winsock proxy server first looks for the destination address in the local Address table and, if it exists, is referred to the original Winsock dynamic link library on the client for local request processing, otherwise redirecting it to Microsoft Proxy server to complete the connection to the external network. The sock proxy supports the SOCK4.3A protocol, the application system accesses the Internet through the Socks Interface Library, and implements the proxy for TCP/IP, FTP, Telnet, Gopher service. In general, the proxy server primarily intercepts all Internet requests by the user and replaces them with the proxy server in lieu of the user requesting information from the target site and then passing the results back to the user host. In practical applications, one or two proxy servers can be selected to run. It is worth mentioning that the latter two proxy servers do not provide caching capabilities.

Second, the implementation of the Microsoft Agent service system.
1, the system composed of a typical intranet agent system can be represented in the following figure: NT4, DNS, IIS, FTP, MAIL server, RAS, WINS, IIS BBS NEWS Server Proxy Server Routeror Modeminternetswitch hub WS hub hub ws WS WS WS in this system, the hardware is connected to a server with a switched hub high speed port, where the client is connected through a normal port and a multilevel hub, and the remote part is connected by a modem and a telephone line or router and a dedicated line. The software uses NT4.0, IIS, Netscape Mail Server2.0, Netscape News Server2.01, Microsoft Proxy Server2.0. This system can realize to the domestic and foreign website proxy or only to the foreign website implementation agent.

2, software Installation and configuration
(1) Software Installation Web server: Install NT4.0, DNS, and IIS in turn.

Proxy Server: Install NT4.0, Service Pack3 for NT4.0, RAS, then run MSP.exe install Microsoft Proxy Server2.0 and generate a shared directory mspclnt.

Mail and newsgroup servers: Install NT4.0, Netscape Mail Server2.0, and Netscape News Server2.01 in turn.

Client: Install WINDOWS95, NETSCAPE Communictor4.03, then open the proxy Server mspclnt directory, run setup.exe files, install Agent client software.

(2) Proxy Server configuration Open the Start button--> "Programs"--> "Microsoft Proxy Server"--> "Internet ServiceManager", the Server Management window appears, double-click the Web, Winsock and SOCKS proxy server name, enter Configuration window: Service Entry contains four subkeys:

Packet Filter: Sets whether to control the IP packets coming from the external network to prevent illegal intrusion.

Security Domain Filters: Set up personal computers, workgroups, and domains that are not allowed to be accessed. Alerting: Alert the suspect data set, send an email to the manager or record it in the NT event log.

Configuration: Sets the service and dial schedule that needs to be dialed.

Auto dialcredential: Fill in the dial-up Networking name, username and password.

Client configuration: Set proxy server name or IP address, configure client browser automatically, do not need proxy client IP address and domain name, or proxy access to Web site inside LAN. An IP address that is accessed directly without requiring a proxy.

Local address Table: Enter an internal domain network addressing range to differentiate the external Internet IP address.

Permissions: For each service item such as FTP, WWW, set up the agent's user and access rights.

Caching: Set cache size, those protocols use caching, save only those site information and save time.

Routing: Sets the first proxy server, and the next step is to send it directly to the Internet or to the next proxy server.

Publishing: Sets the Web server name, path, and URL address for the user to publish the Web page.

(3) Client Configuration Run Netscape communictor4.03--> "edit"--> "Preferences"--> "Advanced"--> "proxy Server", if you select "Manually configure Proxy Server", click "View", Enter the address and port number of the proxy server, select Configure Proxy Server automatically, enter the URL that provides the configuration file, and click Overload.

Third, improve the efficiency of the agent service system compared with the LAN, remote network transmission speed is much slower, LAN users through the proxy service and a line to access the Internet, with the increase of Internet users and information flow, the proxy server may have a larger workload, which requires improved proxy server performance, So that it can effectively handle the communication inside and outside the network, not to create congestion or speed too slow. To do this, the following countermeasures can be used. First, the use of high-end computer-borne, reduce the CPU front run time, such as not running other applications, remove screen protection functions, etc. second, to the proxy server to remove other services, such as DHCP services, workstation services, etc. third, set up a large buffer, so that the client as far as possible from the buffer to The correct configuration of the agent system, so that the system is safe and efficient operation; V, the use of multiple proxy servers, the average distribution of network users.

An optimized system that can handle connections of dozens of or hundreds of users.