0.0.0.0/0 (Default Route (Any Address))
Default routeRFC 4632
0.0.0.0/0 at a glance
| CIDR block | 0.0.0.0/0 |
|---|---|
| First address | 0.0.0.0 |
| Last address | 255.255.255.255 |
| Total addresses | 4,294,967,296 |
| Subnet mask | 0.0.0.0 |
| Prefix length | /0 |
| Type | Default route |
| Publicly routable | Yes |
| Defined in | RFC 4632 |
Open in CIDR calculator/0 subnet details
What is 0.0.0.0/0 used for?
0.0.0.0/0 matches every IPv4 address. In a routing table it is the default route, used when no more specific route matches; in a firewall rule or security group it means "any address". Allowing inbound 0.0.0.0/0 opens a port to the entire internet.
Common subnets of 0.0.0.0/0
FAQ
What does 0.0.0.0/0 mean in a security group?
Any IPv4 address. An inbound rule from 0.0.0.0/0 opens that port to the whole internet; restrict it to known ranges for SSH, RDP and databases.
What is the difference between 0.0.0.0/0 and 0.0.0.0/32?
0.0.0.0/0 matches every IPv4 address; 0.0.0.0/32 matches only the single address 0.0.0.0, the "unspecified" address.