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Quick nmcli notes

This is a quick post so I can remember these details.

So, on the R810, I am currently running ArchLinux, which uses by default NetworkManager, which I have a love/hate relationship with. At my last job, I recommended removing it from our servers, as under RHEL6, it does very odd things to the network and is hard to manage. I have heard that it is better under RHEL7. But, it does let you do some really cool things. On the R810, there is a cellular modem, and on previous installes, I have had it configured and scripted using nmcli to easily bring up and down the cellular connections.

The problem I am facing now is that my current DHCP server for the house does not let me provide two MAC Address for a single IP, so when I dock the R810, it gets a different IP address than when it is on WiFi. Very annoying. Also, for some reason, it would prefer to use WiFi when the ethernet connection was present, thus giving me a slower connection.

The documentation I found was a bit light in examples and/or dated (I am running version 1.6.2 of NetworkManager, and the examples were from 1.2.x or 1.4.x, which did not work). So, with a bit of expermenting, I finally got it fixed to:

  • Chose the ethernet connection over the Wifi when both are present
  • 'Clone' the MAC address of the Wifi NIC to the ethernet NIC

Here are the commands. local is what I called the local ethernet connection, and home-wifi is what I call the house Wifi Network.

  • To set the MAC adress:

nmcli connection modify local ethernet.cloned-mac-address aa:bb:cc:dd:ee:ff

  • To set the connection priorities:

nmcli connection modify local connection.autoconnect-priority 999
nmcli connection modify home-wifi connection.autoconnect-priority 999