Method for preventing IP address cheating in dynamic address allocation

Abstract

Disclosed is a method for preventing IP address cheating in dynamic address allocation. Firstly, check the source MAC address and the source IP address involved in an ARP packet sent from a subscriber terminal, i.e., detect whether there is a matching item in the legal subscriber address table; if so, process it normally, otherwise discard the ARP packet. In this way, an illegal subscriber cannot access to network through IP address cheating, but a legal subscriber can operate normally and continuously. For a subscriber terminal with a static IP address, a static item table is set in the legal subscriber address by manual configuration. When a new subscriber terminal asks for being allocated an IP address, check whether the IP address to be allocated has been set as a static item; if so, inform the subscriber terminal of applying for another IP address. In this way, it is guaranteed that static IP address having been allocated to a subscriber terminal will not be re-allocated, and it is avoided that the subscriber terminal with legal static IP address cannot access to network normally due to the re-allocation of IP address.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001]This application claims priority to Chinese Patent Application No. 02125007.3, filed on Jun. 22, 2002, which is hereby incorporated by reference in its entirety.<?insert-end id="INS-S-00001" ?>FIELD OF THE TECHNOLOGY[0002]The invention relates to an access method of communication network, specifically to a dynamic address allocation method used in a wideband network.BACKGROUND OF THE INVENTION[0003]With the rapid growth of network capacity and vast increase of network complexity, network configuration is getting more complicated. Thus the DHCP (Dynamic Host Configuration Protocol) based on the BOOTP (Bootstrap Protocol) has come into being. With a large expansion, it has been widely used. The DHCP can dynamically assign a duration-limited IP address to an access subscriber terminal. When the duration is ended or the subscriber terminal definitely shows that it would discard the IP address, the IP address can be used by other subscri...

AI Technical Summary

Benefits of technology

[0007]It is an object of the invention to provide a method for preventing IP address cheating in dynamic address allocation. With this method, an illegal user cannot obtain access to a network by IP address cheating, so this method can completely prevent IP address cheating during dynamically allocating an IP address, and can thoroughly ensure the normal usage for legal users.

[0008]The method according to the present invention comprises steps as follow. The exchange checks the source MAC (Medium Access Control) address (hardware address of network adapter) and the source IP address in the ARP packet sent from the subscriber terminal, namely, determine whether there is a matching item in the legal subscriber address table. If there is a matching item in it, the process is dealt with normally, i.e., add the source IP address and the source MAC address in the ARP packet sent from the subscriber terminal as an item to the ARP table, so as to make it possible for the subscriber terminal to access to the network. Otherwise, the packet is discarded.

[0019]The method checks whether the ARP packet sent from a subscriber terminal has a legal address. If there is no matching item in the legal subscriber address table, the packet is discarded. Therefore, an illegal subscriber cannot access to network through IP address cheating, but a legal subscriber can operate normally and continuously. In this way, the problem of IP address cheating is completely solved.

[0020]For the subscriber terminal with static IP address, the static item is manually configured into the legal subscriber address table. When a new subscriber terminal asks for an IP address, it is detected whether the IP address to be allocated is in the static items. If so, the subscriber terminal is informed of applying for another IP address. In this way, it is guaranteed that static IP address having been allocated to a subscriber terminal will not be re-allocated, and it is avoided that the subscriber terminal with legal static IP address cannot access to network normally due to the re-allocation of IP address.

Problems solved by technology

With the rapid growth of network capacity and vast increase of network complexity, network configuration is getting more complicated.

Owing to resource limitation, it is impossible to configure a DHCP server for each network segment, and a DHCP server is usually set at a stand-alone segment for security reason.

While this method cannot solve the problem of IP address cheating root and branch, an IP address cheater may still get access to network.

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