renaming network interface with systemd

At least on Debian stretch, it seems like you need to update-initramfs -u && reboot for *.link files in /etc/systemd/network/ to take effect for existing interfaces.

It seems like the network interfaces get renamed very early during boot from within the initramfs, before the *.link files in /etc/systemd/network are available... and once the interface has been renamed once (/sys/class/net/*/name_assign_type=4), then the the udev-builtin-net_setup_link will no longer emit ID_NET_NAME because should_rename returns false.

Are you using systemd-networkd? I think the .link files are only relevant if you are (instead of the default NetworkManager or legacy initscripts). (I admit I haven't looked deeply into it yet, though.)

I think what you want is a .rules file in /etc/udev/rules.d, something like

SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="mac-address", NAME="wan"

(where mac-address is your actual hex MAC address, of course).

This file needs to be ordered before /usr/lib/udev/rules.d/80-net-setup-link.rules, so the upstream docs suggest /etc/udev/rules.d/70-my-net-names.rules.

For some bad reasons it seems that networkmanager has priority over networkd(who could imagine that?). You can test this as follows:

• systemctl stop NetworkManager
• unplug the network interface
• ip addr

Result: /etc/systemd/network/*.link rules are honored

If you start NetworkManager and repeat the test /etc/systemd/network/*.link is not honored anymore. I tested this with the MACAddressPolicy=random directive