Re: what is the meaning of netmask in pcap_compile() API?

[Guy Harris <guy () alum mit edu>]

On Sat, Nov 29, 2003 at 12:18:33PM +0800, WANG Yong wrote:
> I am using libpcap to receive ISO8473 CLNP/802.2 LLC1 packets from
> network interface and I need to set some filter using pcap_compile()
> API.  This API has a parameter named netmask.  I suppose this is only
> useful when doing jobs related to TCP/IP, so in my case i can safely
> ignore it and set it any value.

It's useful only for the "ip broadcast" filter expression, which checks
for IPv4 broadcasts - it checks whether the "local host" part of the
IPv4 destination address is all 1's.

If you specify 0, filter expressions with "ip broadcast" won't work. 
Everything else will work.
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