DENOG MeetUp 2023-04

After several hardware generations of our servers we had enough of the ever-changing naming schemes of the network interfaces.
This had troubled us in so many different ways:

• "Does this NIC count the ports from left to right or right to left!?" during hardware install.
• Interface names need to be specified in BGP daemon config.
• Prometheus alerting rules specify the interfaces.
• ...

The solution is simple, but very effective:

1. During installation of the server OS, we are installing a small utility binary (ifnamedhcp).
2. This binary iterates over all Ethernet interfaces, does a DHCP request and waits for the response containing a custom Option that specifies the interface name to configure.
3. The name is then configured using systemd-networkd config.