Network Data Flow Of The Design And Realization Of High-speed Acquisition System

As mankind enters the information age, the relationship between internet and people is closer. The internet brings a lot of convenience, but it also has brought many new problems. Internet security is highly valued by many countries and companys.Passive capture is widely used in internet security IDS and firewall. Many softerware used in information sercuity such as tcpdump, ethereal and snort use this mechanism.nowadays, more and more applications become popular in the network, which overload the net.The high performance data collect system is a equipment that use to capture and analyse datas in the internet.Iit can support the data capturing and analysing in a 1000MB level network.The data capture subsystem capture all the data packets while the analyse subsystem can analyse the data from link layer to application layer.this system offer a interface for a secondly development,which can let others to develop many other content–based network security equipment,such as IDS,firewall,and so on.Based on the above points,we realized the data packets capture subsystem which belong to the high performance data collect system by using the"zero copy"technology.It can capture the data packets effectively and safely. It is composed of the following parts:(1) Memory map technology.We use this technology in the system to make the kernel and the application to share the memory.This memory is use to store the data packets and the data structures that use to manage the memory.This memory will be a support to the high-speed transporting of the data packets from kernel and application.(2)"Zero copy"technology.This system will change the way that submitting a data packet from the netcard to the application. It avoids the entering theTCP/IP protocol stack in the kernel, which will reduce the efficiency of a data tansport.(3) The interface to the protocol revert subsystem.in this system.the protocol revert subsystem which located in the application space will analyse the data packets by regist callback functions.This mechanism give a effective and flexible way for the protocol revert subsystem.it can satisfy different request by registing different combination of callback functions.Additionally, a low-level data packets capture subsystem based on PC with linux 2.6 was designed according to the article requirements.