Re: Setting MACADDR with nmcli

[Robert Moskowitz <rgm htt-consult com>]

Thank you!

On 08/07/2018 09:07 AM, Thomas Haller wrote:
> On Tue, 2018-08-07 at 08:43 -0400, Robert Moskowitz wrote:
> > I hope this is the right list for nmcli.
> >
> > I want to set MACADDR in ifcfg-eth0
> >
> > I thought it was:
> >
> > nmcli con mod eth0 mac "02:67:15:00:81:0B"
> >
> > but this sets HWADDR, which has a totally different use.  I could
> > then
> > change HWADDR to MACADDR with:
> >
> > sed -i -e "s/HWADDR/MACADDR/w /dev/stdout"
> > /etc/sysconfig/network-scripts/ifcfg-eth0
> >
> > But that is a hack.  It would be nice to be able to directly set
> > MACADDR, but I cannot find any documentation that states how to do
> > this.
> >
> > thanks
> Hi,
>
> $ nmcli connection modify "$PROFILE" ethernet.cloned-mac-address "$MAC"

I wonder what the history of naming this object 'cloned' mac address?  
Perhaps because we were cloning the address of the broken card for the 
new card so the licensed software would work?  :)

I did that a lot in my early days with 3com cards and VAX ethernet adapters.

Now we use it for ARM boards (and others) that come without a MAC 
address and the uboot or OS has to invent some local scope address.

> Theoretically, this is documented in `man nm-settings`. However, the
> manual is generated and for cloned-mac-address the
> generated documentation is confusing. It's confusing, because `man nm-
> settings` is undecided whether it documents libnm GObject properties or
> D-bus API. Especially, since you care about nmcli syntax. In most
> cases, there is little difference between libnm API, D-Bus API and
> nmcli, so "nm-settings" manual does apply. For "cloned-mac-address"
> it's different.
>
> And as you seem concerned about ifcfg files, see also
> `man nm-settings-ifcfg-rh`. But usually, you would not concern yourself
> with the details of ifcfg files.

You do for ARM based servers.  No GUI typically.  Fixed IP addressing 
and the like and a predictable MAC addr.  Sometimes the uboot is 
consistent for a given board on how it computes the MAC address.  Of 
course a new version of uboot may compute it differently.

So perhaps there is a more modern method than using ifcfg files for 
servers.  I have not encountered it.  I have at least switched from hand 
coding my ifcfg to using nmcli in scripts.

> If you look at `man nmcli` it has a table:
>
> PROPERTY ALIASES
>
>         Table 3. Wired Ethernet options
>         ┌───────────┬──────────────────────────┐
>         │Alias      │ Property                 │
>         ├───────────┼──────────────────────────┤
>         │mtu        │ wired.mtu                │
>         ├───────────┼──────────────────────────┤
>         │mac        │ wired.mac-address        │
>         ├───────────┼──────────────────────────┤
>         │cloned-mac │ wired.cloned-mac-address │
>         └───────────┴──────────────────────────┘

And you have to realize that mac maps to HWADDR to link the ifcfg to a 
specific card. While cloned-mac maps to MACADDR to set the MAC address 
actually used for an interface.  I had to read a lot to tease that 
distinction out.

> best,
> Thomas

Again, thanks

Robert