0.0 0.0 0 ip address

Sometimes we often configure software such as MySQL so that it can connect remotely, so we use the IP address 0.0.0.0, here is an example.

bind-address        = 0.0.0.0

This means that we have set the IP address to be 0.0.0.0, which means that anyone can connect to the MySQL server.

Also, sometimes when we set up the Liunx firewall, we set the IP address to 0.0.0.0/0 to be unreachable, which means that other IP addresses are excluded from accessing the services on this server.

Meaning of 0.0.0.0

In IPV4, the 0.0.0.0 address is used to indicate an invalid, unknown or unavailable destination.

In servers, 0.0.0.0 refers to all IPV4 addresses on the local machine. If a host has two IP addresses, 192.168.50.1 and 10.1.6.1, and a service on that host is listening at 0.0.0.0, then the service can be accessed through both IP addresses.

In routing, 0.0.0.0 is the default route, i.e. the route that corresponds when no exact match is found in the routing table.

Summary of uses

• Used to indicate the host itself when a host has not yet been assigned an IP address. (When DHCP assigns an IP address)

• Used as a default route to indicate "any IPV4 host".

• Used to indicate that the target machine is not available.

• Used as a server side to indicate an arbitrary IPV4 address on the local machine.

If we need to allow access to our IP address when configuring some software services and we don't know our IP address, we can use the IP Address Lookup Tool to look up our IP address.

These are some explanations of the 0.0.0.0 IP address and also the IP address of 0.0.0.0 is described in RFC1700 as follows.

{0,0}: Both the network number and host number are zero, which means "unspecified (i.e. invalid, meaningless) address" and can only be used as a source address.