Date: Tue, 14 Aug 2001 02:49:59 +0100 From: George Reid <greid@FreeBSD.org> To: Wing Tim <twchim1@hotmail.com> Cc: freebsd-questions@FreeBSD.org Subject: Re: Programming on Berkeley Packet Filter (bpf) Message-ID: <20010814024959.A64143@FreeBSD.org> In-Reply-To: <F2025oXibxZxjbP3SIG0000542d@hotmail.com>; from twchim1@hotmail.com on Mon, Aug 13, 2001 at 11:46:10PM %2B0800 References: <F2025oXibxZxjbP3SIG0000542d@hotmail.com>
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On Mon, Aug 13, 2001 at 11:46:10PM +0800, Wing Tim wrote:
> Hi all,
> From the man page of BPF(4), I found there're lots of useful functions
> such as BIOCGBLEN, BIOCSBLEN, BIOCGDLT, ... , BIOCGSTATS. I tried to write a
> should program to use these functions as follows:
Those aren't functions, those are command codes that you can pass to
ioctl(2) for an opened bpf device.
> main ()
> {
> printf(BIOCGBLEN);
> ...
> }
...is nonsense.
> By the way, how can I specify which interface I want to snoop data on?
> Could anyone kindly give me a help? Thanks!
I think you need to read a basic UNIX programming guide before you start
playing around with BPF. However, in answer to your question, the network
device is specified with the BIOCSETIF ioctl.
--
+-------------------+---------------------+
| George Reid | FreeBSD Committer |
| +44 7740 197460 | greid@FreeBSD.org |
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