How to start writting a packet sniffer in Linux?

Martijn van Oosterhout kleptog at
Wed Dec 19 09:26:22 EST 2001

On Tue, Dec 18, 2001 at 10:45:30PM +0800, darren wrote:
> Hi all
> I am a newbie trying to write a Packet Sniffer for WLAN based on either
> the Cisco Card or the Linksys WPC11. I hope that I can also get to know
> the OS better through this process.

Don't want to sound discouraging, but there are already dozens of packet
sniffers for linux, some of which are far better than any one person could
write. What's wrong with all of them?

> Where can I get information on the way Net Packets are being handled by
> Linux, and in particular, available APIs for me to base my development
> on.

Look up the documentation for the kernel net stuff although maybe getting
the source to tcpdump or ethereal would be more helpful.

Martijn van Oosterhout <kleptog at>
> Terrorists can only take my life. Only my government can take my freedom.

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