target/linux/etrax-2.6/image/e100boot/src/libpcap-0.4/README

   1 @(#) $Header: /usr/local/cvs/linux/tools/build/e100boot/libpcap-0.4/README,v 1.1 1999/08/26 10:05:19 johana Exp $ (LBL)
   2
   3 LIBPCAP 0.4
   4 Lawrence Berkeley National Laboratory
   5 Network Research Group
   6 libpcap@ee.lbl.gov
   7 ftp://ftp.ee.lbl.gov/libpcap.tar.Z
   8
   9 This directory contains source code for libpcap, a system-independent
  10 interface for user-level packet capture.  libpcap provides a portable
  11 framework for low-level network monitoring.  Applications include
  12 network statistics collection, security monitoring, network debugging,
  13 etc.  Since almost every system vendor provides a different interface
  14 for packet capture, and since we've developed several tools that
  15 require this functionality, we've created this system-independent API
  16 to ease in porting and to alleviate the need for several
  17 system-dependent packet capture modules in each application.
  18
  19 Note well: this interface is new and is likely to change.
  20
  21 The libpcap interface supports a filtering mechanism based on the
  22 architecture in the BSD packet filter.  BPF is described in the 1993
  23 Winter Usenix paper ``The BSD Packet Filter: A New Architecture for
  24 User-level Packet Capture''.  A compressed postscript version is in:
  25
  26         ftp://ftp.ee.lbl.gov/papers/bpf-usenix93.ps.Z.
  27
  28 Although most packet capture interfaces support in-kernel filtering,
  29 libpcap utilizes in-kernel filtering only for the BPF interface.
  30 On systems that don't have BPF, all packets are read into user-space
  31 and the BPF filters are evaluated in the libpcap library, incurring
  32 added overhead (especially, for selective filters).  Ideally, libpcap
  33 would translate BPF filters into a filter program that is compatible
  34 with the underlying kernel subsystem, but this is not yet implemented.
  35
  36 BPF is standard in 4.4BSD, BSD/386, NetBSD, and FreeBSD.  DEC OSF/1
  37 uses the packetfilter interface but has been extended to accept BPF
  38 filters (which libpcap utilizes).  Also, you can add BPF filter support
  39 to Ultrix using the kernel source and/or object patches available in:
  40
  41         ftp://gatekeeper.dec.com/pub/DEC/net/bpfext42.tar.Z.
  42
  43 Problems, bugs, questions, desirable enhancements, source code
  44 contributions, etc., should be sent to the email address
  45 "libpcap@ee.lbl.gov".
  46
  47  - Steve McCanne
  48    Craig Leres
  49    Van Jacobson