dial-up access is a cheap and practical way to access the Internet for small groups of users or home users. On the LAN, through Proxy Server software can solve the problem of multi-user sharing access to the Internet, the proxy server is essentially a bridge between the user community and the Internet, in order to achieve its network users access to the Internet.
using local Area network
At present, the LAN network products are many, Ethernet switches or hubs (hub) Low prices, very easy to realize the interconnection of local area network customers. Taking the existing campus network as an example, this paper illustrates how to use proxy proxy server to realize Internet connection and analyze the internal routing of Proxy Server. The topology of this local area network is shown in Figure 1, the LAN is composed of a number of clients, a server, a dial-up network server, a modem connected to the Internet.
The specific configuration is as follows:
1. Client: Install Windows 95/98,ie Browser (Internet Explorer4.0 or 5.0). In Internet Explorer, in the "Options, Connections" column, select "Use proxy server to access the Internet," and the proxy server's IP address and port number (80) into the address and port items, this completes the client's simple configuration.
2, Server: Install Windows NT and proxy software. Configure the server's RAS, dial-up Networking, TCP/IP, and so on, set up Windows user accounts, start proxy software, start Web, FTP, and other proxy tasks and set permissions to give customers access to the Internet and so on.
3, the modem: Configure a modem on the server side, a telephone line. Dial local Internet telephony, such as 169, 163, and so on.
4, dial-up network server: In the local area network for remote users to provide services, so that remote users can connect through the dedicated communication lines with the local area network.
routing problems for proxy servers
After configuring the server's RAS service and dial-up networking, make a dial-up connection. At this time the proxy server is equivalent to the existence of two interface cards, that is, a network card and a modem, you can think of it as a RoutersTo provide routing forwarding to customers and the outside world, you must view and adjust the routing settings for the server to ensure normal communication between the server and the customer.
Dial on the server to view the server's routing table in DOS mode through the route command. The following is a simple example of a default route to analyze the routing table of the NT server in the dialing process, assuming that 10.119.40.254 is the gateway to the network segment of the server and 10.119.40.49 the IP address of the NT Server network card.
Pre-Dial Server routing table (table 1):
Network address NETMASK GATEWAY INTERFACE METRIC
0.0.0.0 0.0.0.0 10.119.40.254 10.119.40.49 1
After dialing the Server Routing table (table 2):
Network address NETMASK GATEWAY INTERFACE METRIC
0.0.0.0 0.0.0.0 10.119.40.254 10.119.40.49 2
0.0.0.0 0.0.0.0 10.18.168.168 10.18.168.168 1
Where 10.18.168.168 is assigned to the IP address of this dial-up network (modem) for an Internet server. By comparing table 1 and table 2, the default routes before and after dialing have changed. The main reason for this is that the "default gateway to use Dial-up networking" is selected in the "Dial-up Networking" and "TCP/IP Settings" option in the server, so that every time the server sends a message to a customer on the 10.119.40.0 network segment, it first passes through the 10.18.168.168 address. When customers on the network require access to an Internet site, they go through the LAN to the NT server each time, and then to the modem. Therefore, the client and the server must be guaranteed normal connectivity, so that the routing process through the 10.119.40.49 LAN network card. The ping command is used to detect that the server can ping the client, while the client pings the server with a timeout (time out). This phenomenon indicates that the default routing of the proxy server has changed, so that the client-server connectivity first passes through 10.18 168.168来 forwarding. To solve this problem, the following settings should be made, assuming that a customer's network segment is 122.103.1.0,submask:255.255.255.0, you need to add the specified item to the routing table, that is, execute the command route ADD 122.103.1.0 255.255.255.0 10.119.40.49. Where 10.119.40.49 is the NT Server's network card IP address, and then view the Server routing table as follows:
Network address NETMASK GATEWAY INTERFACE METRIC
0.0.0.0 0.0.0.0 10.119.40.254 10.119.40.49 2
0.0.0.0 0.0.0.0 10.18.168.168 10.18.168.168 1
122.103.1.0 255.255.255.0 10.199.40.254 10.119.40.49 1
Further analysis, we can also achieve our goal by modifying the default route, that is, to use the route ADD 0.0.0.0 0.0.0.0 10.119.40.49 1 IF metric=2
Make the routing table set to:
Network address NETMASK GATEWAY INTERFACE METRIC
0.0.0.0 0.0.0.0 10.119.40.254 10.119.40.49 1
As a special case, we analyze the routing problem of the local area network remote user. There are remote users on the local area network that are typically connected to a local area network through a dedicated communication line and must configure the routing table on the NT Server if they attempt to access the Internet through a proxy server. Because such remote users have 2 dial-up services to access the Internet, the direct routing settings are especially necessary on the proxy proxy server. As mentioned above, customers of a local area network can also connect the server to the customer by modifying the default route. For remote clients, the routing of the Proxy server must be set directly. Assume that a remote user (dial-up networking Server) is in a 122.100.1.0,submask:255.255.255.0 network segment and must add a route: ROUTE add 122.100.1.0 255.255.255.0 10.119.40.49 in order to ensure the passthrough of remote users. Otherwise, when the client dials the local area network, the remote client can ping all other devices on the network, except to ping the NT Server timeout error. This means that the proxy server's default route does not work at this time.
Management of the user
Each agent user can be managed through Windows NT. When a customer accesses the Internet, the user is authenticated first on the proxy server, and the user enters a normal username and password to provide Internet services and then access the Internet through a proxy server. Proxy Server Software can use MS Proxy 2.0, which provides a large number of control of proxy permissions, it can be authorized users, access to the site, such as easy to manage, monitor, record and so on.
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