Satyajeet Seth wrote:
>
> Hi
>
> I tried to use ng_ether and ng_bpf as follows:
>
> fxp0(lower) --- (bhook)[bpf](nomatch)(hook1)----(upper)fxp0
> [ ]( match )(hook2)----not connected
>
> $ ngctl mkpeer fxp0: bpf divert bhook
>
> $ ngctl name fxp0:divert bpf0
>
> $ ngctl
> + msg bpf0: setprogram { thisHook="bhook" ifMatch="hook2"
> ifNotMatch="hook1" bpf_prog_len=1 bpf_prog=[ { code=6 } ] }
>
> Now 'nghook -a bpf0: hook1' shows output while 'nghook -a bpf0: hook2'
> doesn't.
>
> $ ngctl connect fxp0: bpf0: upper hook1
>
> 1. After this I am unable to ping any of the lan machines.
> Could you suggest what I could be doing wrong?
>
> 2. I am writing a BPF program(for filtering packets destined to particular
> MAC addresses) by converting instructions like:
> BPF_STMT(BPF_LD+BPF_H+BPF_ABS,12), BPF_STMT(BPF_RET+BPF_K,0)
> into:
> [ {code=28 jt=0 jf=0 k=0x0c} {code=6 jt=0 jf=0 k=0}]
> After seeing the definitions of BPF_STMT,BPF_LD etc. in /sys/net/bpf.h. Is
> this the correct way?
>
> 3. I noticed a problem that the filter could not be set as :
> ngctl msg bpf0: setprogram {...}
> It gave the message:
> ngctl: send msg: Invalid argument
that's becaue you must escape the arguments so that the shell does not try
to interpret things.
>
> I am using FreeBSD 4.1.
>
> Thanks
> Satya
>
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the man page for -current ng_bpf (you can get it from
http://www.freebsd.org/cgi/cvsweb.cgi/src/share/man/man4/ng_bpf.4
shows how to program a bpf node with a good example
(it was not in the 4.x man page)
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