Understanding Peer Connections in Bitcoin Core

As a Bitcoin Core 27.0 user, you’re probably experiencing some changes to your peer connections. One question that’s been on many users’ minds is why their peers are still connecting over older versions of Bitcoin Core, specifically v1.

In this article, we’ll dive into the details behind how Bitcoin Core updates its peer connections and why it might still be using an older version like v1.

Bitcoin Core 27.0: The New Standard

Bitcoin Core 27.0 was released a few days ago and brings significant improvements to the protocol, including support for new features such as BIP324 (Transport Layer Security) for peer-to-peer communication. This update enables v2 transport over P2P connections.

Why V1 is Still Being Used

So why isn’t Bitcoin Core 27.0 defaulting to v2 transport for all peers? The answer lies in the way the protocol handles peer connections and version detection.

When you run bitcoin-qt --version in your terminal, the output will display the version number of Bitcoin Core running on your system. In this case, if your core is 27.0 or newer, it is likely that the v2 transport is enabled by default.

However, peer connections are not determined solely by the core version; they are also based on a specific user agent (UA) string. The UA string identifies the client and server components of a Bitcoin node. In this case, your peers have a UA string P2P_V2, which indicates that they are using the v2 transport.

The /Satoshi:27.0.0/ user agent

Now, this is where things get interesting. The string /Satoshi:27.0.0/ is used for configuration of /Satoshi:27.0.0/. This means that if your peers are running Bitcoin Core 27.0 or newer, they will automatically be using v2 transport for P2P connections.

The case for older peers

If you are seeing connections from older peers running an earlier version of Bitcoin Core (e.g. v1), it is likely that these peers have been configured to use the older version by default. This can happen for a few reasons:

• Older versions of Bitcoin Core can still be used as fallbacks in certain scenarios, such as when a new update is not available.

• Some users or systems may have manual settings that allow them to use an older version of Bitcoin Core.

Conclusion

In conclusion, the reason your peers are still connecting on older versions of Bitcoin Core (v1) is likely due to the default v2 transport configuration enabled by Bitcoin Core 27.0. The user agent string /Satoshi:27.0.0/ indicates that these peers are configured to use v2 transport, while any other peers with an earlier version may still be using v1.

As you continue to explore and update your Bitcoin Core configuration, keep an eye on changes to your peer connections. With each new version, you will likely see more updates to the protocol and its configuration options.