### Packet Filter

This is a more complete example of libpcap usage. It shows, among other things, how to create and set filters and how to save a capture to disk. It can be compiled under Win32 or Unix (projects and makefiles are provided). Pcap_filter (pf.exe) is a general-purpose packet filtering application: its input parameters are a source of packets (it can be a physical interface or a file), a filter and an output file. It takes packets from the source until CTRL+C is pressed or the whole file is processed, applies the filter to the incoming packets and saves them to the output file if they satisfy the filter. Pcap_filter can be used to dump network data according to a particular filter, but also to extract a set of packets from a previously saved file. The format of both input and output files is the format used by libpcap, i.e. same of WinDump, tcpdump and many other network tools.