* How does the linux kernel select the MAC address for TAP devices?
@ 2014-06-16 8:00 Albert Krenz
2014-06-16 13:39 ` Vlad Yasevich
2014-06-17 10:25 ` Daniel Borkmann
0 siblings, 2 replies; 3+ messages in thread
From: Albert Krenz @ 2014-06-16 8:00 UTC (permalink / raw)
To: netdev
As stated in the email subject: Where does the kernel get the used
MAC-Adress for a newly create TAP device? Are they randomly generated
or does it select one from a fixed pool of reserved MAC-Adresses?
I have not found any official documentation about the selection of
MAC-addresses for TAP-devices. Most sites like
http://backreference.org/2010/03/26/tuntap-interface-tutorial/ state
that the MAC addresses are auto-generated and can be changed. But they
do not explain the generation rules.
Does anyone know an official document (preferably from kernel.org)
explaining the MAC selection process? Or is it only explained in the
Source?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: How does the linux kernel select the MAC address for TAP devices?
2014-06-16 8:00 How does the linux kernel select the MAC address for TAP devices? Albert Krenz
@ 2014-06-16 13:39 ` Vlad Yasevich
2014-06-17 10:25 ` Daniel Borkmann
1 sibling, 0 replies; 3+ messages in thread
From: Vlad Yasevich @ 2014-06-16 13:39 UTC (permalink / raw)
To: Albert Krenz, netdev
On 06/16/2014 04:00 AM, Albert Krenz wrote:
> As stated in the email subject: Where does the kernel get the used
> MAC-Adress for a newly create TAP device? Are they randomly generated
> or does it select one from a fixed pool of reserved MAC-Adresses?
>
> I have not found any official documentation about the selection of
> MAC-addresses for TAP-devices. Most sites like
> http://backreference.org/2010/03/26/tuntap-interface-tutorial/ state
> that the MAC addresses are auto-generated and can be changed. But they
> do not explain the generation rules.
>
> Does anyone know an official document (preferably from kernel.org)
> explaining the MAC selection process? Or is it only explained in the
> Source?
Yes, it is explained in the source. In particular look at the function
tun_net_init(). The default MAC is random.
-vlad
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: How does the linux kernel select the MAC address for TAP devices?
2014-06-16 8:00 How does the linux kernel select the MAC address for TAP devices? Albert Krenz
2014-06-16 13:39 ` Vlad Yasevich
@ 2014-06-17 10:25 ` Daniel Borkmann
1 sibling, 0 replies; 3+ messages in thread
From: Daniel Borkmann @ 2014-06-17 10:25 UTC (permalink / raw)
To: Albert Krenz; +Cc: netdev
On 06/16/2014 10:00 AM, Albert Krenz wrote:
> As stated in the email subject: Where does the kernel get the used
> MAC-Adress for a newly create TAP device? Are they randomly generated
> or does it select one from a fixed pool of reserved MAC-Adresses?
>
> I have not found any official documentation about the selection of
> MAC-addresses for TAP-devices. Most sites like
> http://backreference.org/2010/03/26/tuntap-interface-tutorial/ state
> that the MAC addresses are auto-generated and can be changed. But they
> do not explain the generation rules.
>
> Does anyone know an official document (preferably from kernel.org)
> explaining the MAC selection process? Or is it only explained in the
> Source?
See: drivers/net/tun.c +936
^ permalink raw reply [flat|nested] 3+ messages in thread
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2014-06-16 8:00 How does the linux kernel select the MAC address for TAP devices? Albert Krenz
2014-06-16 13:39 ` Vlad Yasevich
2014-06-17 10:25 ` Daniel Borkmann
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