releng: Improve WWAN support
As the mailing list thread [arch-general] Arch intallation using usb-modem shows, installing Arch using a WWAN/mobile broadband connection is not a painless experience. We should strive to improve this somehow.
Basically we need to:
connect to the mobile network using something,
use systemd-networkd for DHCP.
Looking at the options in https://wiki.archlinux.org/index.php/USB_3G_Modem#Connection, the easiest appears to be ModemManager. It should just work with:
$ mmcli -m 0 --simple-connect="pin=INSERT_PIN_HERE,apn=INSERT_APN_HERE,user=INSERT_USER_HERE,password=INSERT_PASSWORD_HERE"
For the command itself only
apn is required, others depend on the ISP and the SIM card settings.
For systemd-networkd, it's as simple as configuring DHCP for
ww* interfaces. This would match the configuration for Ethernet and Wi-Fi interfaces, i.e. DHCP by default and those who need static addresses must configure it manually.
[Match] Type=wwan [Network] DHCP=yes IPv6PrivacyExtensions=yes [DHCPv4] RouteMetric=2048 [DHCPv6] RouteMetric=2048