Bitcoin Core and Tor

[defa1]

I'm running Core 0.21.0 on Ubuntu 20.04 with Tor running in the background as a service. I'm interested in running Core over Tor, but I'm confused by the options offered to me in the GUI under Options > Network.

Could someone explain to me the difference between these 2 options:

- Connect through SOCKS5 proxy (default proxy)
- Use seperate SOCKS5 proxy to reach peers via Tor onion services

In case it matters, I do not allow incoming connections.

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[NotATether]

The first one routes all of your Bitcoin Core traffic through a Tor proxy including traffic being sent to nodes listening with .onion urls.

The second one uses a separate proxy just for accessing onion URLs, and makes a direct connection with everything else such as IP addresses for clearnet nodes and DNS requests for peer lists.

[defa1]

There is something that I'm missing because I don't understand what you mean with "nodes listening with .onion urls"

By checking the first option I can route everything through Tor. Will I then connect to both nodes on the clearnet and nodes running only as a hidden service?

Or do I need to check the second option to connect to nodes that are running as a hidden service?

Is there a benefit of checking both options?

[NotATether]

There is something that I'm missing because I don't understand what you mean with "nodes listening with .onion urls"

A node can set a configuration option to bind to a .onion address such as x83jdie73d.onion (which is not real but you get the idea) the same way that programs bind to IP addresses. That means those services become accessible by sending and receiving data from that address.

This allows a node to become accessible to all via its IP address, and also it's onion address on Tor.

By checking the first option I can route everything through Tor. Will I then connect to both nodes on the clearnet and nodes running only as a hidden service?

Yes.

Or do I need to check the second option to connect to nodes that are running as a hidden service?

Is there a benefit of checking both options?

As far as I know, no. The first option of routing everything through Tor implies the second option. Because the second option mainly exists so that you don't have download all block and transaction data from nodes on the clearnet using Tor, while simultaneously being able to download from nodes that are only accessible via Tor.

[Carlton Banks]

Or do I need to check the second option to connect to nodes that are running as a hidden service?

Is there a benefit of checking both options?

As far as I know, no. The first option of routing everything through Tor implies the second option. Because the second option mainly exists so that you don't have download all block and transaction data from nodes on the clearnet using Tor, while simultaneously being able to download from nodes that are only accessible via Tor.

in the past (several years back), there was a bug in Bitcoin Core related to the Socks5 proxy options... I forget the details, but using the "separate socks proxy for Tor connections" was causing a problem IIRC

if you're only connecting via Tor, then using the separate Tor-only socks proxy isn't necessary, you can set only the socks proxy and it will work fine. The separate socks proxy for Tor-only is only necessary if you are running 2 proxies simultaneously, one for for Tor and another for a proxy to some other alternate network routing. I expect most people are only using a Tor proxy as their alternate (or only) network, so the second Tor-only setting is not needed.

In future (i.e. probably Bitcoin 22.0), using both proxy settings may become more common, as I2P support is coming in that release. I think the CJDNS protocol is already supported in 0.21.0, as all it requires is already in the new address format that comes with Bitcoin 0.21.0, not 100% sure on that however