init-scripts/docs/network.md

Static Network Configuration

The default configuration provides multiple services that perform network initialization and static configuration using helper scripts that require programs from the iproute2 package.

Configuration files are typically stored in /etc/netcfg/ (depending on configure options).

Please note that the loopback device is treated specially and not included in any of the network configuration outlined below. The loopback device is brought up and configured by a dedicated service long before the network configuration is done.

Interface Renaming

If the ifrename service is enabled (it is disabled by default), network interfaces are renamed based on a rule set stored in the file ifrename. The file contains comma separated shell globing patterns for the current interface name, MAC address and a prefix for the new interface name.

For each network interface, rules are processed top to bottom. If the first two globing patterns apply, the interface is renamed. Interfaces with the same prefix are sorted by mac address and a running index is appended to the prefix.

If none of the rules apply, the interface name is left unchanged.

The intent is, to provide a way to configure persistent, deterministic names for at least all network interfaces that are permanently installed on a board.

Extension cards or external network adapters should be given a different prefix to avoid changes in the order as they come and go.

Static Interface and Route Configuration

After interface renaming, an iproute2 batch script /etc/netcfg/static is executed with the -force option is set, i.e. it will plough throug the entire script without aborting, but the service will be marked as having failed if any of the batch lines fail.

Net Filter Tables

An additional service is provided that restores the nft rule set from /etc/nftables.rules.

DHCP based network configuration

If the configure option --enable-dhcpclient is set, two services are added. The service dhpcdmaster launches a global dhcpcd instance.

For each port that should be configured via DHCP, the service dhcpcd needs to be enabled manually with the port name as argument. The service the runs after the master service and sends a signal to the master to operate on that port.