| Currently, libpcap supports packet capturing on Linux 2.6.27 and later; |
| earlier versions are not supported. libpcap will not work if the kernel |
| does not have the packet socket option enabled. |
|
|
| You must configure 2.6.x kernels with the CONFIG_PACKET_MMAP option for |
| this protocol. 3.x and later kernels do not require that. |
|
|
| Note that, by default, libpcap will, if libnl is present, build with it; |
| it uses libnl to support monitor mode on mac80211 devices. There is a |
| configuration option to disable building with libnl, but, if that option |
| is chosen, the monitor-mode APIs (as used by tcpdump's "-I" flag, and as |
| will probably be used by other applications in the future) won't work |
| properly on mac80211 devices. |
|
|
| libnl-tiny can be used when libnl is not available. This works using |
| Autoconf only and requires the provided libnl-tiny to have sufficient |
| pkg-config support. |
|
|
| Linux's run-time linker allows shared libraries to be linked with other |
| shared libraries, which means that if an older version of a shared |
| library doesn't require routines from some other shared library, and a |
| later version of the shared library does require those routines, the |
| later version of the shared library can be linked with that other shared |
| library and, if it's otherwise binary-compatible with the older version, |
| can replace that older version without breaking applications built with |
| the older version, and without breaking configure scripts or the build |
| procedure for applications whose configure script doesn't use the |
| pcap-config script if they build with the shared library. (The build |
| procedure for applications whose configure scripts use the pcap-config |
| script if present will not break even if they build with the static |
| library.) |
|
|
| Statistics: |
| Statistics reported by pcap are platform specific. The statistics |
| reported by pcap_stats on Linux are as follows: |
|
|
| ps_recv Number of packets that were accepted by the pcap filter |
| ps_drop Number of packets that had passed filtering but were not |
| passed on to pcap due to things like buffer shortage, etc. |
| This is useful because these are packets you are interested in |
| but won't be reported by, for example, tcpdump output. |
|
|
