Re: Change destination MAC

Op vr, 18-02-2005 te 13:40 +0100, schreef George:
> Hello.
> 
> I'm developing a kernel module in order to change the MAC address to the 
> one I desired. For that I'm using the netfilter/ebtables hook. However I'm 
> facing a problem, I don't know the reason why it happens.
> The module works fine and seems to do its job. However that depends on the 
> dest MAC address I put to the packet.
> Let's explain it. If the dest MAC addr is under the control of the brigde 
> (brctl showmacs br0) there is no problem when changing it, I can put 
> whatever within this list.
> However if I put another different from the ones in the list, the packet is 
> not sent. I'm sniffing the channel and no packet get out of the device.
> 
> When exiting the NF_BR_POST_ROUTING it seems that the mac has been changed, 
> but the packet never gets out.
> 
> Any reason for that.
> Any help is more than welcome.

Have a look at ebt_snat.c

Try not changing nfcache and using the test (see ebt_snat.c)
if (skb_shared(*pskb) || skb_cloned(*pskb))

Btw, dnat is usually done on the PREROUTING hook. If you do dnat to a
host on a different side of the bridge your packet won't arrive unless
you use the PREROUTING hook.

cheers,
Bart




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