Network interface aliases

Alias sections can be used to define further IPv4 and IPv6 addresses for interfaces. They also allow combinations like DHCP on the main interface and a static IPv6 address in the alias, for example to deploy IPv6 on wan while keeping normal internet connectivity. Each interface can have multiple aliases attached to it.

Create an 'interface' section per IP, but alias interfaces may NOT be of type bridge.

For non-bridged interfaces (physdev, that is physical interfaces) the device is the <interface-of-network-for-same-phydev>.
For cases where the interface is bridged the device is br-base_interface, where base_interface is the name of the primary IP's config section (e.g. for a the default lan interface config, the first alias would use device br-lan).

A minimal alias definition for a bridged interface might be (for a scenario without VLANs):

config interface 'lan'
	option device 'eth0'
	option type 'bridge'
	option proto 'static'
	option ipaddr '192.168.1.1'
	option netmask '255.255.255.0'
 
config interface 'lan1'
	option device '@lan'
	option proto 'dhcp'
 
config interface 'lan2'
	option device '@lan'
	option proto 'static'
	option ipaddr '10.0.0.1'
	option netmask '255.255.255.0'

For a non-bridge interface:

config interface 'lan'
	option device 'eth0'
	option proto 'static'
	option ipaddr '192.168.1.1'
	option netmask '255.255.255.0'
 
config interface 'lan1'
	option device 'eth0'
	option proto 'dhcp'
 
config interface 'lan2'
	option device 'eth0'
	option proto 'static'
	option ipaddr '10.0.0.1'
	option netmask '255.255.255.0'

To see a list of interfaces you can do ubus list network.interface.* and to view the ip of a particular interface (the UCI name not the physical interface), do ifstatus <interface> (e.g. ifstatus lan2).

Name	Type	Required	Default	Description
`interface`	string	yes	(none)	Specifies the logical interface name of the parent (or master) interface this alias belongs to; must refer to one of the defined `interface` sections
`proto`	string	yes	(none)	Specifies the alias interface protocol
`ipaddr`	ip address	yes, if no `ip6addr` is set	(none)	alias IP address
`netmask`	netmask	yes, if no `ip6addr` is set	(none)	alias Netmask
`gateway`	ip address	no	(none)	Default gateway
`broadcast`	ip address	no	(none)	Broadcast address (autogenerated if not set)
`ip6addr`	ipv6 address	yes, if no `ipaddr` is set	(none)	IPv6 address (CIDR notation)
`ip6gw`	ipv6 address	no	(none)	IPv6 default gateway
`dns`	list of ip addresses	no	(none)	DNS server(s)
`layer`	integer	no	`3`	Selects the interface to attach to for stacked protocols (tun over bridge over eth, ppp over eth or similar). 3: attach to layer 3 interface (tun, ppp if parent is layer 3 else fallback to 2) 2: attach to layer 2 interface (br-* if parent is bridge else fallback to layer 1) 1: attach to layer 1 interface (eth, wlan)

please check if this is still true or not: At the time of writing, only the static protocol type is allowed for aliases.

Network interface aliases

Options for Alias sections