[Snort-users] BPF filter
Chris.Reid at ...2817...
Mon Apr 21 00:59:09 EDT 2003
Pay attention to the section OPTIONS, where it explains "expression". To
quote this man page, a BPF filter...:
selects which packets will be dumped. If no
expression is given, all packets on the net will be
dumped. Otherwise, only packets for which expres-sion
is `true' will be dumped.
----- Original Message -----
From: "Liuhy" <solar_liu at ...8882...>
To: "snort-users" <snort-users at lists.sourceforge.net>
Sent: Monday, April 21, 2003 1:33 AM
Subject: [Snort-users] BPF filter
> Hello everyone,
> In the option of snort command line, there is a "-F", which is
followed by a BPF filter file. I have googled it, I only know that it is
the abbreviation of "Berkley Packet Filtering", these cann't give me the
answer that I want to get. My questions are:
> 1. What is BPF filter? (not introduced in "man tcpdump", "man snort", I
cann't enter "man 4 bpf in linux)
> 2. How can I write BPF filter file? what is the rules to write it?
> 3. In snort FAQ, there is an example as following: snort <options> ``not
( (icmp = 8 or icmp = 0) and host <foo>)''
> It's similar to a snort command line, is it right? what is the
relation of them?
> Thanks in advance!
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