CN1921496B - A method for DHCP client to identify DHCP server - Google Patents

Abstract

The present invention aims to provide a method for a DHCP client to identify a DHCP server, comprising the following steps: the DHCP client sets trusted DHCP server information; the DHCP client sends a DHCP discovery packet, and the DHCP server in the network responds to the request and sends a DHCP Provide data packets; the DHCP client responds to the DHCP provided data packets from the DHCP server, analyzes the information of the DHCP server, and if it conforms to the set trust information, continues the DHCP negotiation process, otherwise directly discards the packets. The invention realizes the qualified identification of the DHCP server, and solves the problem that the DHCP client cannot normally access the network caused by the uncertainty of assigning IP addresses when there are multiple DHCP servers in the existing network.

Description

A method for DHCP client to identify DHCP server

technical field

The present invention relates to the field of data communication, in particular to DHCP (Dynamic Host Configuration Protocol, dynamic host configuration protocol) technology.

Background technique

The full name of DHCP is Dynamic Host Configuration Protocol (Dynamic Host Configuration Protocol), which is designed by IETF (Internet Network Engineer Task Force), and the detailed protocol content is specified in RFC document RFC2131. DHCP is an extension of BOOTP (Bootstrap Protocol, see RFC951). It is based on the C/S mode. It provides a mechanism for dynamically specifying IP addresses and configuration parameters. It is mainly used in large-scale network environments and places where manual configuration is difficult. The network administrator concentrates the setting parameters of the TCP/IP network on the server running DHCP, and the DHCP server automatically specifies IP addresses and routing configurations for the hosts in the network, that is, the clients. The configuration parameters that the DHCP server can specify are some It is not related to the IP protocol, but it will not affect the communication between computers. Its configuration parameters make the computer communication on the network convenient and easy to realize. And DHCP can rent IP addresses, which is a more prominent function compared to BOOTP, especially for large-scale networks with many computers, such as a campus network in a university, each computer has a static IP address Sometimes it may be unnecessary. The DHCP server specifies a lease period for each IP address. The lease period can be 1 minute or indefinite. The client can also continue to use IP resources by renewing the lease. When the lease expires, the DHCP server can reclaim the IP address and distribute it to other machines. In addition, DHCP can also satisfy mobile services very well. Because DHCP provides a reservation mechanism, although the physical location of the client has changed, the basic information of the client still exists in the server. When the client sends a request again, if the IP address Previously used addresses can still be used if they have not been allocated.

The existing DHCP technology can be well used in the enterprise's internal LAN, greatly reducing the burden of TCP/IP network planning, management and maintenance, and automatically assigning and recycling IP addresses, basically without human intervention. However, the existing DHCP networking method does not limit the DHCP server. If there are multiple DHCP servers in the network, it may cause the DHCP client to fail to identify the trusted DHCP server and assign an inappropriate IP address, resulting in Therefore, the corresponding network functions cannot be performed normally.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the shortcoming that the DHCP client in the prior art lacks the DHCP server identification mechanism, and then provide a method for the DHCP client to identify the DHCP server, make full use of the convenient network management characteristics of DHCP, and cooperate with The identification function of the DHCP server realizes the user's DHCP client access.

The invention provides a method for a DHCP client to identify a DHCP server, and the technical solution comprises the following steps:

Step 1: The DHCP client sets the trusted DHCP server information;

Step 2: The DHCP client sends a DHCP discovery packet, and the DHCP server in the network responds to the request and sends a DHCP offer packet;

Step 3: The DHCP client provides a data packet for the DHCP response of the DHCP server, and analyzes the information of the DHCP server. If it conforms to the set trust information, then continue the DHCP negotiation process and perform step 4, otherwise directly discard the message;

Step 4: Determining the DHCP client as a trusted DHCP server, the DHCP client accepts the IP address assigned by the DHCP server and the content of related configuration information, and accesses the designated requested network.

Compared with the prior art, the present invention realizes the qualified identification of the DHCP server through the information of the trusted DHCP server specified by the DHCP client, and solves the uncertainty of assigning IP addresses when there are multiple DHCP servers in the existing network. The DHCP client cannot access the network normally.

Description of drawings

Fig. 1 is a flow chart of the method of the present invention;

Fig. 2 is a system model diagram of the application of the method of the present invention.

Detailed ways

The specific realization of the access service of the DHCP client in the present invention will be further described below with reference to the accompanying drawings and embodiments.

Fig. 2 is the system model of the application of the inventive method: in the local area network, there are many DHCP servers, the DHCP client can be identified by the inventive method to recognize the trusted DHCP server, and accept its allocation of IP addresses and related configurations information function.

With reference to Fig. 1, the present invention proposes two embodiments.

The first embodiment comprises the following steps:

In the first step, the client specifies the MAC address information of the trusted DHCP server;

In the second step, the DHCP client sends a DHCP discovery (DHCP DISCOVER) packet, and the DHCP server that receives the DHCP DISCOVER packet responds to the request and sends a DHCP offer (DHCP OFFER) packet;

In the third step, the DHCP client resolves the MAC address of the DHCP server for the DHCP OFFER packet responded by the DHCP server;

The fourth step is to determine whether the parsed MAC address matches the MAC address of the trusted DHCP server set by the client. If it matches, the subsequent DHCP negotiation process will be carried out; if not, the packet will be discarded directly.

For the DHCP server judged as trusted by the DHCP client, the DHCP client accepts the content of the IP address and related configuration information assigned by the DHCP server, and accesses the designated requested network.

The second embodiment comprises the following steps:

In the first step, the client specifies the IP address of the trusted DHCP server;

In the second step, the DHCP client sends a DHCP DISCOVER packet, and the DHCP server that receives the DHCP DISCOVER packet responds to the request and sends a DHCPOFFER packet;

In the third step, the DHCP client resolves the IP address of the DHCP server for the DHCP OFFER packet responded by the DHCP server;

The fourth step is to judge whether the resolved IP address matches the trusted DHCP server IP address set by the client. If it matches, the subsequent DHCP negotiation process will be carried out; if not, the packet will be discarded directly.

For the DHCP server judged as trusted by the DHCP client, the DHCP client accepts the content of the IP address and related configuration information assigned by the DHCP server, and accesses the designated requested network.

In summary, the method of the present invention well integrates the characteristics of DHCP that are convenient for network management, and at the same time meets the requirements of the DHCP client for the authentication of the requested DHCP server, and creatively provides a way for the DHCP client to access the broadband network. was expanded.

Of course, the present invention can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the present invention without departing from the spirit and essence of the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (3)

1. the method for dhcp client identification Dynamic Host Configuration Protocol server may further comprise the steps:

Step 1: dhcp client is provided with the Dynamic Host Configuration Protocol server information of being trusted;

Step 2: dhcp client sends DHCP and finds packet, this request of dhcp server response and send DHCP packet is provided in the network;

Step 3: dhcp client provides packet at the DHCP of dhcp server response, resolves the information of this Dynamic Host Configuration Protocol server, if meet the trust information of setting, then continues DHCP negotiations process and execution in step four, otherwise direct dropping packets;

Step 4: dhcp client is judged to be the Dynamic Host Configuration Protocol server of being trusted, and dhcp client is accepted the content of this Dynamic Host Configuration Protocol server distributing IP address and relevant configuration information, is linked in the network of specified request.

2. method according to claim 1 is characterized in that, it is the mac address information of specifying Dynamic Host Configuration Protocol server that dhcp client is provided with the Dynamic Host Configuration Protocol server information of being trusted.

3. method according to claim 1 is characterized in that, it is the IP address of specifying Dynamic Host Configuration Protocol server that dhcp client is provided with the Dynamic Host Configuration Protocol server information of being trusted.

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