Add all the RFC1918 unroutable private networks.

https://en.wikipedia.org/wiki/Private_network

    10.0.0.0 – 10.255.255.255 (10.0.0.0/8)
    172.16.0.0 – 172.31.255.255 (172.16.0.0/12)
    192.168.0.0 - 192.168.255.255 (192.168.0.0/16)
    127.0.0.0 - 127.255.255.255 (127.0.0.0/8)

https://tools.ietf.org/html/rfc1918

Possibly also 100.64.0.0/10 for carriers.

https://tools.ietf.org/html/rfc6598#page-8