Suggestion to update documentation to use "::" instead of "0.0.0.0" for binding

[GuillaumeOuint]

Issue description
Currently, many documentation pages on grpc.io reference binding to 0.0.0.0, which explicitly limits the service to IPv4. This approach is increasingly outdated, as modern systems and best practices are shifting toward full IPv6 support.

To better align with current web standards and accommodate environments that are IPv6-only, the documentation should recommend using :: instead of 0.0.0.0 when binding to all interfaces. The :: address supports both IPv6 and dual-stack configurations (when supported by the platform), ensuring broader compatibility and future-proofing.

Additionally, referencing :: in the documentation helps promote IPv6 adoption by raising awareness. Many developers are still unfamiliar with IPv6 or are not actively considering it in their deployments. By using :: as the default example, the documentation can serve as a subtle but valuable educational tool, encouraging developers to think about modern networking requirements and nudging them toward more future-ready setups.

[shivaspeaks]

CC: @ejona86

[ejona86]

Did you actually see an error when going through the guide? Which language did you notice this with? What OS are you using?

The languages with docs containing 0.0.0.0: web, node, cpp, ruby, php

I checked the C++ example, and using 0.0.0.0 has it bind to *:50051 as displayed in ss -lt. The greeter client is also able to contact it via [::1]:50051. That's the same results I see when listening on [::]:50051. Not specifying the ip address (:50051) causes a crash.

[GuillaumeOuint]

@ejona86 Just to clarify, I'm not reporting a bug, it's more about what the documentation recommends.

Using 0.0.0.0 in examples suggests that you're only binding to IPv4. On modern Linux systems, binding to :: usually covers both IPv6 and IPv4 through dual-stack support like 0.0.0.0, unless ipv6only=1 is set. So while 0.0.0.0 works, it's really the OS that's allowing IPv6 connections behind the scenes, not something gRPC handles directly (same for :: but at least, it's binding to IPv6 by default).
At the end, the result is the same, dual stack binding.

That's why I think the docs should lean toward using :: by default. It makes/keep the intent to bind to all interfaces, including IPv6, more explicitly. But beyond that, it also helps raise awareness that IPv6 traffic exists and needs to be considered. Right now, many developers and sysadmins only think in IPv4 terms. As a result, they might forget to configure IPv6 firewall rules properly, or ignore IPv6 entirely, even when it's already active.

By showing :: in the docs, we can nudge developers to recognize IPv6 as part of their actual network surface. That helps improve firewall setups, monitoring, and encourages more real-world IPv6 usage.

I'm mostly using Go and JS, but this really applies across the board. It's about promoting better habits and making things a bit more future-proof.

Appreciate you taking the time to dig into this!