Ignoring destination MAC address in incoming packets

Ignoring destination MAC address in incoming packets

[Krzysztof Halasa]

Hi,

I have a bit unusual problem today. Is there a way to ignore destination
MAC address in incoming packets?

I need to do this on Atheros Wi-Fi. Basically what I need to achieve is
a sniffer.

Something like this:
- ATH5k working in ad-hoc mode, certain ESSID and channel selected.
- UDP packets in certain range are to be forwarded to other IPs.
- the wifi interface must be able to normally communicate (within its
  ESSID and channel).
- it has to work with iptables etc. (DNAT, routing).

I know I can change a line in the kernel (the one setting pkt_type to
OTHER_HOST) but perhaps there is some standard way for things like this?

Or should I use AF_PACKET and forward the data with userspace helper?

Any other idea?

TIA.
-- 
Krzysztof Halasa

Re: Ignoring destination MAC address in incoming packets

[Antonio Quartulli]

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On Mon, Apr 08, 2013 at 09:08:21AM +0200, Krzysztof Halasa wrote:
> Hi,
> 
> I have a bit unusual problem today. Is there a way to ignore destination
> MAC address in incoming packets?
> 
> I need to do this on Atheros Wi-Fi. Basically what I need to achieve is
> a sniffer.
> 
> Something like this:
> - ATH5k working in ad-hoc mode, certain ESSID and channel selected.
> - UDP packets in certain range are to be forwarded to other IPs.
> - the wifi interface must be able to normally communicate (within its
>   ESSID and channel).
> - it has to work with iptables etc. (DNAT, routing).
> 
> I know I can change a line in the kernel (the one setting pkt_type to
> OTHER_HOST) but perhaps there is some standard way for things like this?
> 
> Or should I use AF_PACKET and forward the data with userspace helper?
> 
> Any other idea?

May be a stupid suggestion, but what about setting promisc mode on?

Cheers,

-- 
Antonio Quartulli

..each of us alone is worth nothing..
Ernesto "Che" Guevara

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Re: Ignoring destination MAC address in incoming packets

[Krzysztof Halasa]

Antonio Quartulli <ordex@autistici.org> writes:

> May be a stupid suggestion, but what about setting promisc mode on?

I use promiscuous mode, but the packets are still dropped because
skb->pkt_type = PACKET_OTHERHOST (since the destination MAC address
doesn't match and is not broadcast/multicast).

I realize accepting all packets blindly opens a can of worms and this
must be well thought. Perhaps a user space tool using AF_PACKET is a
better way?
-- 
Krzysztof Halasa