What does ip address 0.0.0.0 mean?

The first time I saw that addres I was a bit con­fused. I used to think that 127.0.0.1 was the only way to refer to your local machine. Turns out, 0.0.0.0 is another way to do this, but with a sub­tle difference.

If your local server lis­tens on 127.0.0.1, you need to spec­ify the port on which the server lis­tens to incom­ing requests whereas if your local server lis­tens on 0.0.0.0, your server auto­mat­i­cally lis­tens to incom­ing requests on all open ports.

E.g.
A server lis­ten­ing on 127.0.0.1:8000 would lis­ten to requests to port 8000 but a server lis­ten­ing on 0.0.0.1 would lis­ten to requests on any open port on the system.

One use case for using 0.0.0.0 would be if you are using a vir­tu­al­iza­tion layer such as docker where each con­tainer runs a sin­gle ser­vice and the port that it receives requests from can be con­fig­ured externally.

Ryan Sukale

Ryan is just a regular guy next door trying to manage his life and finances.

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