A method for filtering dhcp data packets in local area network

Abstract

The invention discloses a method for filtering a DHCP data package of a local area network. According to the method, a middle layer between a network card drive and a protocol drive filters network data packages, sent to a DHCP client, in the local area network, and filtering comprises the four steps of network data package collecting, network data package screening, DHCP data package analyzing and network data package processing. The DHCP data package is gradually separated from the network data packages sent to the DHCP client, and is analyzed, a legal data package sent by a designated DHCP server is received, a data package sent by an illegal DHCP server is discarded, and therefore the aim that the DHCP client obtains the IP address from the designated DHCP server is achieved, the illegal DHCP server is prevented from distributing the IP address to the DHCP client, and meanwhile, the invention further discloses a system for filtering the DHCP data package of the local area network.

Description

technical field [0001] The invention relates to the field of computer application technology and computer network technology, in particular to a method and system for filtering DHCP data packets in a local area network. Background technique [0002] The DHCP protocol is the abbreviation of the Dynamic Host Configuration Protocol (Dynamic Host Configuration Protocol). It is widely used in medium and small LANs, especially in large and medium LANs, such as university campus networks and large enterprise networks. There are so many clients in these networks that it is almost impossible to manually assign a network IP (Internet Protocol, Internet Protocol) address, so dynamically assigning IP addresses to clients in the network through the DHCP protocol becomes an optimal solution. [0003] However, the network administrators of these large and medium-sized LANs can generally only grasp the number of legal DHCP servers in the network. The number of DHCP servers is not easy to ...

AI Technical Summary

Problems solved by technology

[0003] However, the network administrators of these large and medium-sized LANs can generally only grasp the number of legal DHCP servers in the network. The number of DHCP servers is not easy to grasp, so there are often many legal and illegal DHCP servers in these large and medium-sized LANs, and the disadvantage of the DHCP protocol is that each DHCP client connected to the LAN needs to broadcast to the LAN. Send a DHCP discover data packet to find a DHCP server, and the DHCP server that receives the data packet will respond, select one of the IP addresses that have not been leased in its own address pool to assign to the requesting DHCP client, and pass the DHCP offer data packet Send to the DHCP client, if the DHCP client receives the response information from multiple DHCP servers, the DHCP client will only receive the response information from the first received DHCP server, and then send the DHCP request broadcast data to the LAN packet, telling all the DHCP servers in the LAN that it has accepted the IP address provided by which DHCP server. At this time, other DHCP servers that receive the DHCP request packet will take back the IP address just allocated, thus generating a The problem is that if the IP address received by the DHCP client is not the IP address assigned by the DHCP server it wants, it will cause many problems, such as the DHCP client cannot access the Internet, or the DHCP client cannot access some intranet resources. Or the DHCP client is connected to an unsafe internal network, resulting in illegal access to the DHCP client, illegal interception and analysis of network data packets, etc.

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