Re: How to tell if a network interface was renamed (and from what)

On 21 Nov 2023, at 12:16, Mina Galić wrote:

> Hi Mike,
>
>> Mina, do you care about epair, or is the behavior I described sufficient
>> for your purposes?
>
> I do deeply care about epair, but for me, ifinfo does the
> right thing for me:
>
> root@irc:~ # ifinfo | grep Interface
> Interface vnet0 (epair30):
> Interface lo0 (lo0):

That's not the whole story for epair.  For example, I get this:

Interface bhyve (vtnet0):
Interface lo0 (lo0):
Interface lo1 (lo1):
Interface foo0a (epair0):
Interface foo0b (epair0):

But if you only need the driver name, it will do.

A problem with ifinfo is that it is not normally installed.
I think it is worth adding a similar feature for the driver name
to ifconfig.

> for one. For the other. For the main purpose, figuring out
> in cloud-init what the driver of an interface is / if the
> interface has been renamed, this is more than sufficient.

Currently I have this for ifconfig -D:

bhyve: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500
        options=80028<VLAN_MTU,JUMBO_MTU,LINKSTATE>
        ether 58:9c:fc:0b:0c:10
        inet 10.0.3.1 netmask 0xffffff00 broadcast 10.0.3.255
        inet6 fe80::5a9c:fcff:fe0b:c10%bhyve prefixlen 64 scopeid 0x1
        inet6 2001:470:c202:3::1 prefixlen 64
        media: Ethernet autoselect (10Gbase-T <full-duplex>)
        status: active
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        drivername: vtnet0

It's a little more work to parse, but I decided that it was useful
for humans, and works with -a.

		Mike
>
> Thank you very much,
>
> Mina