Date: Mon, 06 Feb 2017 19:53:12 +0000 From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: "Giulio Ferro" <auryn@zirakzigil.org> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: Duplicate MAC addresses in VNET epair interaces Message-ID: <8B1A6A6C-4280-4B96-9D60-FC9E7EEE2222@lists.zabbadoz.net> In-Reply-To: <472069af-0f9d-d830-064b-2d984a5774ae@zirakzigil.org> References: <472069af-0f9d-d830-064b-2d984a5774ae@zirakzigil.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 6 Feb 2017, at 18:53, Giulio Ferro wrote:
> Hi all,
>
>
> Setup:
>
> 11.0-STABLE FreeBSD 11.0-STABLE #0 r312338: Tue Jan 17 12:29:38 UTC
> 2017
>
>
> I've set up two freebsd hosts, each of which has a single VNET jail.
>
> On each host I've created 2 epair interfaces.
>
> Host A
>
> - epair0a, epair1a on the host
>
> - epair0b, epair1b on the jail
>
>
> Host B
>
> - epair0a, epair10a on the host
>
> - epair0b, epair10b on the jail
>
>
> What I noticed is that on both hosts, each epair interface has the
> same MAC address:
>
…>
>
> (same behavior on the epair interfaces on the jail side)
>
>
> As you can see, the mac addresses seems to depend on the order of the
> creation of the epair, not on the name or address
>
>
> This is a potentially bad behavior, because if I want to bridge say
> epair1a on A with epair10a on B with a VPN or
>
> a physical connection giving 192.168.1.1 to epair1b and 192.168.1.2 to
> epair10b, I won't be able to make them
>
> talk to each other since they have the same MAC address.
>
>
> My question is: is this a bug or something I'm doing wrong? If there
> any workaround I can use?
From the man page:
Like any other Ethernet interface, an epair needs to have a
network
address. Each epair will be assigned a locally administered
address by
default, that is only guaranteed to be unique within one network
stack.
To change the default addresses one may use the SIOCSIFADDR
ioctl(2) or
ifconfig(8) utility.
I thought someone patched it a few years ago to have a pseudo-random
part to make collisions less likely and use the FreeBSD vendor space,
but it seems that never happened for epair (or didn’t make it into the
tree).
ifconfig epair<x>[ab] ether 02:xx:xx:xx:xx is your friend for now.
/bz
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?8B1A6A6C-4280-4B96-9D60-FC9E7EEE2222>