Method and device for filtering data stream contents
A technology of content filtering and data flow, applied to electrical components, transmission systems, etc., can solve problems such as the inability to detect network worms and the inability to cut off data flow
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[0128] Embodiment 1. In the embodiment of the present invention, the data packet is a TCP packet. The feature code set of the network worm virus to be detected by the firewall is {HE, SHE, HIS, HERZWXY}. When the firewall is initialized, DFA is constructed based on the feature code set, as shown in Table 1. The firewall is set to cache "last come first come" packets. In the embodiment of the present invention, the firewall only needs to filter the content of each TCP packet sent by the sender, that is, the preset direction is forward. Then the firewall is tracking the TCP data flow, and the process of filtering the contents of the TCP data flow can be found in Figure 4 ,include:
[0129] Step 401: the firewall receives a SYN message, the sequence number of which is S1.
[0130] In the embodiment of the present invention, the SYN message, the SYNACK message, and the FIN message are special TCP messages, wherein the SYN message and the SYNACK message are link establishment m...
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