Untagged Frames

Untagged Frames

[Jonathan Tripathy]

Hi Everyone,

Does ebtables have the facility to make sure that any frames entering a 
bridge must be untagged (i.e. have no 802.1q tag)?

Thanks

Re: Untagged Frames

[Pascal Hambourg]

Hello,

Jonathan Tripathy a écrit :
> 
> Does ebtables have the facility to make sure that any frames entering a 
> bridge must be untagged (i.e. have no 802.1q tag)?

I guess that it can be done by matching the 802.1q ethertype 0x8100.

Re: Untagged Frames

[Pascal Hambourg]

Jonathan Tripathy a écrit :
>>
>> Does ebtables have the facility to make sure that any frames entering a
>> bridge must be untagged (i.e. have no 802.1q tag)?
> 
> I guess that it can be done by matching the 802.1q ethertype 0x8100.
> 
> ------------------------------------------------------------------------------
> 
> So I'm guessing if I only wanted to allow untagged frames going into my
> bridge, I could do:
> 
> ebtables -I FORWARD -p ! 0x8100 -i <IF of port connected to bridge> -j
> ACCEPT

FORWARD = frames going through the bridge, not all frames entering it.

> Is that correct? I don't need to use physdev (like I do in iptables) or
> anything, do I?

-i in ebtables is the same as --physdev-in in iptables : both are used
to match the bridge port (physical interface). If you want to match the
logical bridge interface, use --logical-in in ebtables or -i in iptables.

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