Get list of ethernet devices

Marco Steinbach coco at
Mon Nov 7 01:24:53 UTC 2011

On Mon, 7 Nov 2011, Michael Ross wrote:

> Moin,


> I'm setting up a system on an external USB drive,
> serving as fallback in case of a server failure:
> Customer takes USB drive, plugs it into any of his PCs and boots of it.
> Now I am looking for a good method to configure the network:
> I could just start dhclient on any NIC which could possibly be there,
> thus cramming rc.conf with
> 	ifconfig_em0="DHCP"
> 	ifconfig_em1="DHCP"
> 	ifconfig_fxp0="DHCP"
> and so on.
> Or I could grep ifconfig or dmesg output for ethernet interfaces and dhclient 
> these.
> Both sound like a very messy solution.
> So I would step beyond my current area of expertise, grep some source from 
> sysinstall, bsdinstall or somewhere and do it in C.
> But I'm kind of hoping anybody can point me to a readymade solution yet 
> unknown to me.

No readymade solution, just a hint for possibly keeping the mess down a bit:

The l (lower case letter L) flag to ifconfig lists all available interfaces in a more scripting friendly fashion:

% ifconfig -l
em0 dc0 plip0 lo0 vboxnet0

I'd be interested in testing the results (or possible steps thereto) of your efforts in creating a customized, bootable FreeBSD USB stick image, if that's feasible.

MfG CoCo

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