$ curl ipip.ooo
$ curl -4 ipip.ooo
$ curl -6 ipip.ooo
$ curl ipip.ooo/country
$ curl -L ipip.ooo/dns
$ curl -L ipip.ooo/dnscountry
GET https://4.ipip.ooo
GET https://6.ipip.ooo
GET https://ipip.ooo/ip/8.8.8.8