Corresponds to Linux struct in_ifaddr. A list of these addresses is stored in Ipv4Interface. This class is modelled after how current Linux handles IP aliasing for IPv4. Notably, aliasing of IPv4 interfaces (e.g., "eth0:1") is not used, and instead an interface is assigned possibly multiple addresses, with each address being classified as being primary and secondary. See the iproute2 documentation for this distinction.