From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: How does the linux kernel select the MAC address for TAP devices? Date: Tue, 17 Jun 2014 12:25:29 +0200 Message-ID: <53A01799.5060304@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Albert Krenz Return-path: Received: from mx1.redhat.com ([209.132.183.28]:31601 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753935AbaFQKZd (ORCPT ); Tue, 17 Jun 2014 06:25:33 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: 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