1Currently, libpcap supports packet capturing on Linux 2.6.27 and later; 2earlier versions are not supported. 3 4You must configure 2.6.x kernels with the CONFIG_PACKET_MMAP option for 5this protocol. 3.x and later kernels do not require that. 6 7Note that, by default, libpcap will, if libnl is present, build with it; 8it uses libnl to support monitor mode on mac80211 devices. There is a 9configuration option to disable building with libnl, but, if that option 10is chosen, the monitor-mode APIs (as used by tcpdump's "-I" flag, and as 11will probably be used by other applications in the future) won't work 12properly on mac80211 devices. 13 14Linux's run-time linker allows shared libraries to be linked with other 15shared libraries, which means that if an older version of a shared 16library doesn't require routines from some other shared library, and a 17later version of the shared library does require those routines, the 18later version of the shared library can be linked with that other shared 19library and, if it's otherwise binary-compatible with the older version, 20can replace that older version without breaking applications built with 21the older version, and without breaking configure scripts or the build 22procedure for applications whose configure script doesn't use the 23pcap-config script if they build with the shared library. (The build 24procedure for applications whose configure scripts use the pcap-config 25script if present will not break even if they build with the static 26library.) 27 28Statistics: 29Statistics reported by pcap are platform specific. The statistics 30reported by pcap_stats on Linux are as follows: 31 32ps_recv Number of packets that were accepted by the pcap filter 33ps_drop Number of packets that had passed filtering but were not 34 passed on to pcap due to things like buffer shortage, etc. 35 This is useful because these are packets you are interested in 36 but won't be reported by, for example, tcpdump output. 37