::/0 (IPv6 Default Route)
Default routeRFC 4291
::/0 at a glance
| CIDR block | ::/0 |
|---|---|
| First address | :: |
| Last address | ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff |
| Total addresses | 2¹²⁸ |
| Prefix mask | :: |
| Prefix length | /0 |
| Type | Default route |
| Publicly routable | Yes |
| Defined in | RFC 4291 |
What is ::/0 used for?
::/0 matches every IPv6 address. It is the IPv6 default route and, in firewall rules or security groups, means "any IPv6 address". Remember to restrict ::/0 as well as 0.0.0.0/0 when opening ports.
FAQ
What does ::/0 mean in a security group?
Any IPv6 address. If you allow 0.0.0.0/0, check whether a ::/0 rule exists as well; otherwise the port may be open, or closed, to IPv6 clients without you noticing.
What is the IPv6 default route?
::/0. It is usually learned from router advertisements and points to the router's link-local address.