What is ebtables used for ?

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xoy74
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Joined: 05 Dec 2007
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PostPosted: Tue Jul 26, 2016 12:48    Post subject: What is ebtables used for ? Reply with quote
I just set up a DD-WRT on a Linksys EA6400 and I noticed the CPU usage is pretty high (over 1.0) so I checked what's going on and ebtables is always at the top of the list with 50% of the CPU usage.
Not sure what it's being used for, as I don't see it running on other DD-WRT routers I use.
Specifically, I see this:
Code:

/usr/sbin/ebtables -t nat -D POSTROUTING -o tap1 --pkttype-type multicast -j DROP

However, I don't have any OpenVPN client or server using TAP devices or any Ethernet over IP tunnels.
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Per Yngve Berg
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PostPosted: Tue Jul 26, 2016 15:49    Post subject: Reply with quote
ebtables is the MAC level counterpart of iptables.
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xoy74
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PostPosted: Wed Jul 27, 2016 13:47    Post subject: Reply with quote
Per Yngve Berg wrote:
ebtables is the MAC level counterpart of iptables.

Any idea which feature/setting may be using it ?
I don't have any specific settings (firewall, qos, access restrictions) that I am using.
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Per Yngve Berg
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PostPosted: Thu Jul 28, 2016 7:43    Post subject: Reply with quote
Looks like an attempt to filter multicast.

Is there anything in the start-up script?
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xoy74
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PostPosted: Tue Aug 09, 2016 18:12    Post subject: Reply with quote
Per Yngve Berg wrote:
Looks like an attempt to filter multicast.

Is there anything in the start-up script?

Thanks, that makes sense but I still don't have any clue where it's coming from. There's nothing in the startup scripts. Plus, the interface tun1 is not used anywhere I know of.
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wenzhuo
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Joined: 22 Apr 2011
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PostPosted: Tue Aug 16, 2016 23:04    Post subject: Reply with quote
Experiencing the same problem, and filed a bug report http://svn.dd-wrt.com/ticket/5502.
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Kermee
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Joined: 19 Jun 2008
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PostPosted: Thu Aug 18, 2016 10:06    Post subject: Reply with quote
This occurs on the R7000 also. Unfortunately, I need ebtables so I had to go back to a firmware version which worked. Hopefully it's fixed soon.

http://www.dd-wrt.com/phpBB2/viewtopic.php?t=303728

Cheers,
Kermee
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wenzhuo
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PostPosted: Thu Aug 18, 2016 23:55    Post subject: Reply with quote
Kermee wrote:
This occurs on the R7000 also. Unfortunately, I need ebtables so I had to go back to a firmware version which worked. Hopefully it's fixed soon.

Which version did you revert to?
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Kermee
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PostPosted: Fri Aug 19, 2016 20:49    Post subject: Reply with quote
wenzhuo wrote:
Kermee wrote:
This occurs on the R7000 also. Unfortunately, I need ebtables so I had to go back to a firmware version which worked. Hopefully it's fixed soon.

Which version did you revert to?


r27745 (2015/08/25) but I have r29193 (03/02/16) running on a test R7000 without issues so far with ebtables.

In my limited testing, it broke somewhere between r29396 (2016/04/04) and r29607 (2016/05/09).

Cheers,
Kermee
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Kermee
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PostPosted: Sat Aug 20, 2016 7:46    Post subject: Reply with quote
Just a quick heads up. DD-WRT v3.0-r30430M kongac (08/16/16) doesn't exhibit the hanging ebtables behavior so I've switched to that firmware for my test R7000 unit.

Cheers,
Kermee
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wenzhuo
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PostPosted: Sun Aug 21, 2016 13:52    Post subject: Reply with quote
Kermee wrote:
Just a quick heads up. DD-WRT v3.0-r30430M kongac (08/16/16) doesn't exhibit the hanging ebtables behavior so I've switched to that firmware for my test R7000 unit.


Is it safe to upgrade from the BS build to the kong build without resetting? I'll be upgrading wzr-1750dhpd remotely (across the pacific ocean) for my sister and needs to be extremely careful.
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Kermee
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PostPosted: Sun Aug 28, 2016 3:18    Post subject: Reply with quote
wenzhuo wrote:
Is it safe to upgrade from the BS build to the kong build without resetting? I'll be upgrading wzr-1750dhpd remotely (across the pacific ocean) for my sister and needs to be extremely careful.


Sorry for the late reply.

I did a 'Reset after Flash' when I went from BS to Kong so I cannot confirm if it's safe to do so. My gut feeling though is you'll probably have to do a reset or weird things might occur. I'm not sure what NVRAM settings are in-sync and out-of-sync between the two builds. Hopefully they'll fix the ebtables thing in the BS builds soon. I'm not even sure what part of the code introduced the bug though I didn't spend much time looking at the changelog on the build that broke ebtables for our devices.

I do report that after about a week of running the Kong build, it has been stable, including the OpenVPN tunnel I have running on it.

Cheers,
Kermee
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Per Yngve Berg
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PostPosted: Sun Aug 28, 2016 9:02    Post subject: Reply with quote
Users have reported it fixed in BS Build 30471
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Kermee
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PostPosted: Sun Aug 28, 2016 18:16    Post subject: Reply with quote
Per Yngve Berg wrote:
Users have reported it fixed in BS Build 30471


Awesome! That's great to hear! Thanks for the update.

Cheers,
Kermee
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xoy74
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Joined: 05 Dec 2007
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PostPosted: Tue Aug 30, 2016 13:46    Post subject: Build 30471 Reply with quote
Confirming that my issue is solved after upgrading to Build 30471.
Thanks !
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