Method and device for accessing outer network from inner network

Abstract

The invention provides a method and a device for accessing an outer network from an inner network, wherein the method is applied to a device possessing a routing function, and the device is used to connect with the inner network and the outer network, and is globally provided with a DNS map strategy. The method includes the steps of searching a corresponding DNS map strategy in accordance with a public network IP address carried by a DNS response message when the device receives the DNS response message returned by a DNS server based on a requirement of accessing the outer network by an inner network host; conversing the public network IP address carried by the DNS response message to a corresponding virtual public network IP address if the searched DNS map strategy requires the conversion of the public network IP address into a virtual public network IP address, and sending the virtual public network IP address to the inner network host corresponding to the returned DNS response message. The method for accessing the outer network from the inner network realizes that the user of a special local area network can normally access a public network server which is conflicted with the IP address of the special local area network.

Description

technical field [0001] The invention relates to network communication technology, in particular to a method and equipment for accessing an external network from an internal network. Background technique [0002] Traditional local area network (LAN) refers to a network composed of multiple computers interconnected in the same area, such as the same office, the same building, and the same company, generally within a few kilometers. Traditional local area network can realize functions such as file management, application software sharing, printer sharing, scheduling within the working group, e-mail and fax communication services. Here, the traditional local area network is closed and can be composed of two computers in an office, or thousands of computers in a company. The main feature is that its internal addresses (such as the IP addresses of internal hosts and servers) are all It is a standard private IP address (this is mainly relative to the globally unique public IP addr...

AI Technical Summary

Problems solved by technology

However, there are many difficulties in the adjustment process. The most troublesome problem is that many early (even now) applications and services in the LAN are bound to a large number of original IP addresses in the program, and these IP addresses are hard-coded in the application. in the program

However, from Figure 1b It can be seen that the DNS response message returned by the DNS server first arrives at the external network interface of the NAT gateway, such as Figure 1b FE1 / 2 in the NAT gateway instead of the internal network interface of the NAT gateway. In this way, because the DNS map policy cannot be applied to the external network interface, DNS map conversion cannot be performed on the IP address carried in the DNS response message, resulting in special The LAN cannot access the public network

Moreover, in the prior art, the DNS map policy is mainly aimed at the public network IP address. Since the host or server in the special local area network is configured with a public network address, when the special local area network accesses the public network, it will of course consider that the DNS response The IP address carried in the message is a private network IP address, not a public network IP address. Therefore, DNS map conversion will not be performed on the IP address carried in the DNS response message, which will cause the special LAN to be unable to access the public network.

Images