Cooper Legal Group, LLC
FTP application layer packet filtering method, device and computer storage medium
Disclosed is a method for Application Specific Packet Filter (ASPF) of a File Transfer Protocol (FTP), including the following steps: when a Transmission Control Protocol (TCP) connection of an FTP control channel is established, a first TCP Synchronous (TCP SYN) packet sent by a client is obtained and forwarded to an FTP server; it is detected whether a response packet from the FTP server is a TCP Synchronize-Acknowledgment (SYN+ACK) packet, and if not, the response packet is discarded; it is detected whether a response packet from the client is an ACK TCP packet, and if not, the response packet is discarded; and a data flow table is created to record and update an FTP state. A device for ASPF of a FTP is also provided. The method and device can avoid and stop the attacks from the FTP application layer, and ensure safe and reliable transmission of an FTP service.
ZTE Corporation
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Yonggang Juan
Gao Li