Tor Hidden Service

A Tor hidden service - now officially called an onion service - is a network endpoint that's only reachable through the Tor network, identified by a .onion address. The endpoint's real IP location is hidden from both the user and the wider internet.

For a Bitcoin node, running as a Tor onion service provides:

• Network-layer privacy. Your real IP doesn't appear in peer lists, isn't visible to chain analysis firms scanning the gossip network, and isn't logged by other node operators.
• Censorship resistance. An onion service's location and IP address are hidden, which the Tor Project says makes it difficult for adversaries to censor it or identify its operator. A blocklist of known Bitcoin node IPs cannot include yours, because the IP behind a .onion address is never announced to the network.
• Protection against eavesdropping attacks. Without your IP, observers can't easily correlate your broadcasts with your physical location or identity.
• A second network to peer over. Since version 26.0, Bitcoin Core keeps at least one outbound connection on every network it can reach, which its release notes say improves resistance to eclipse attacks. A node that is on Tor as well as the clear internet is harder to box in than one on either alone.

The cost is latency. A connection to an onion service runs through six relays, three picked by each side, and the Tor Project's own measurements put the round trip through an onion circuit at a few hundred milliseconds in 2026, about 440 at the median. For Bitcoin's needs - block propagation every ~10 minutes, transactions that propagate over seconds - this latency is essentially invisible in practice. Block- and transaction-relay over Tor work fine.

Bitcoin Core has shipped Tor support since version 0.7 in 2012, and since version 0.12 in 2016 it creates an onion service for you automatically when it can reach a Tor control port. Running your node behind Tor is a single config-file change (proxy=127.0.0.1:9050 plus a few related options). The same hidden-service pattern can also expose RPC for remote management, letting you control your home node from anywhere without opening any firewall ports.

For self-custody users running a full node, running over Tor is the single biggest privacy upgrade you can make at the network layer. Strongly recommended for anyone who cares about not having their on-chain activity correlated with their home IP.

See Privacy on Bitcoin for which leak Tor closes and which ones it does not touch.