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diff --git a/doc/tor.md b/doc/tor.md index 1ba7137b8e..8a2aef2d07 100644 --- a/doc/tor.md +++ b/doc/tor.md @@ -23,14 +23,19 @@ outgoing connections, but more is possible. -proxy=ip:port Set the proxy server. If SOCKS5 is selected (default), this proxy server will be used to try to reach .onion addresses as well. + You need to use -noonion or -onion=0 to explicitly disable + outbound access to onion services. -onion=ip:port Set the proxy server to use for Tor onion services. You do not - need to set this if it's the same as -proxy. You can use -noonion + need to set this if it's the same as -proxy. You can use -onion=0 to explicitly disable access to onion services. + Note: Only the -proxy option sets the proxy for DNS requests; + with -onion they will not route over Tor, so use -proxy if you + have privacy concerns. -listen When using -proxy, listening is disabled by default. If you want - to run an onion service (see next section), you'll need to enable - it explicitly. + to manually configure an onion service (see section 3), you'll + need to enable it explicitly. -connect=X When behind a Tor proxy, you can specify .onion addresses instead -addnode=X of IP addresses or hostnames in these parameters. It requires @@ -40,19 +45,112 @@ outgoing connections, but more is possible. -onlynet=onion Make outgoing connections only to .onion addresses. Incoming connections are not affected by this option. This option can be specified multiple times to allow multiple network types, e.g. - ipv4, ipv6, or onion. + ipv4, ipv6 or onion. If you use this option with values other + than onion you *cannot* disable onion connections; outgoing onion + connections will be enabled when you use -proxy or -onion. Use + -noonion or -onion=0 if you want to be sure there are no outbound + onion connections over the default proxy or your defined -proxy. In a typical situation, this suffices to run behind a Tor proxy: ./bitcoind -proxy=127.0.0.1:9050 +## 2. Automatically create a Bitcoin Core onion service -## 2. Manually create a Bitcoin Core onion service +Bitcoin Core makes use of Tor's control socket API to create and destroy +ephemeral onion services programmatically. This means that if Tor is running and +proper authentication has been configured, Bitcoin Core automatically creates an +onion service to listen on. The goal is to increase the number of available +onion nodes. -If you configure your Tor system accordingly, it is possible to make your node also -reachable from the Tor network. Add these lines to your /etc/tor/torrc (or equivalent -config file): *Needed for Tor version 0.2.7.0 and older versions of Tor only. For newer -versions of Tor see [Section 3](#3-automatically-listen-on-tor).* +This feature is enabled by default if Bitcoin Core is listening (`-listen`) and +it requires a Tor connection to work. It can be explicitly disabled with +`-listenonion=0`. If it is not disabled, it can be configured using the +`-torcontrol` and `-torpassword` settings. + +To see verbose Tor information in the bitcoind debug log, pass `-debug=tor`. + +### Control Port + +You may need to set up the Tor Control Port. On Linux distributions there may be +some or all of the following settings in `/etc/tor/torrc`, generally commented +out by default (if not, add them): + +``` +ControlPort 9051 +CookieAuthentication 1 +CookieAuthFileGroupReadable 1 +``` + +Add or uncomment those, save, and restart Tor (usually `systemctl restart tor` +or `sudo systemctl restart tor` on most systemd-based systems, including recent +Debian and Ubuntu, or just restart the computer). + +On some systems (such as Arch Linux), you may also need to add the following +line: + +``` +DataDirectoryGroupReadable 1 +``` + +### Authentication + +Connecting to Tor's control socket API requires one of two authentication +methods to be configured: cookie authentication or bitcoind's `-torpassword` +configuration option. + +#### Cookie authentication + +For cookie authentication, the user running bitcoind must have read access to +the `CookieAuthFile` specified in the Tor configuration. In some cases this is +preconfigured and the creation of an onion service is automatic. Don't forget to +use the `-debug=tor` bitcoind configuration option to enable Tor debug logging. + +If a permissions problem is seen in the debug log, e.g. `tor: Authentication +cookie /run/tor/control.authcookie could not be opened (check permissions)`, it +can be resolved by adding both the user running Tor and the user running +bitcoind to the same Tor group and setting permissions appropriately. + +On Debian-derived systems, the Tor group will likely be `debian-tor` and one way +to verify could be to list the groups and grep for a "tor" group name: + +``` +getent group | cut -d: -f1 | grep -i tor +``` + +You can also check the group of the cookie file. On most Linux systems, the Tor +auth cookie will usually be `/run/tor/control.authcookie`: + +``` +stat -c '%G' /run/tor/control.authcookie +``` + +Once you have determined the `${TORGROUP}` and selected the `${USER}` that will +run bitcoind, run this as root: + +``` +usermod -a -G ${TORGROUP} ${USER} +``` + +Then restart the computer (or log out) and log in as the `${USER}` that will run +bitcoind. + +#### `torpassword` authentication + +For the `-torpassword=password` option, the password is the clear text form that +was used when generating the hashed password for the `HashedControlPassword` +option in the Tor configuration file. + +The hashed password can be obtained with the command `tor --hash-password +password` (refer to the [Tor Dev +Manual](https://2019.www.torproject.org/docs/tor-manual.html.en) for more +details). + + +## 3. Manually create a Bitcoin Core onion service + +You can also manually configure your node to be reachable from the Tor network. +Add these lines to your `/etc/tor/torrc` (or equivalent config file): HiddenServiceDir /var/lib/tor/bitcoin-service/ HiddenServicePort 8333 127.0.0.1:8334 @@ -106,44 +204,10 @@ for normal IPv4/IPv6 communication, use: ./bitcoind -onion=127.0.0.1:9050 -externalip=7zvj7a2imdgkdbg4f2dryd5rgtrn7upivr5eeij4cicjh65pooxeshid.onion -discover -## 3. Automatically create a Bitcoin Core onion service - -Starting with Tor version 0.2.7.1 it is possible, through Tor's control socket -API, to create and destroy 'ephemeral' onion services programmatically. -Bitcoin Core has been updated to make use of this. - -This means that if Tor is running (and proper authentication has been configured), -Bitcoin Core automatically creates an onion service to listen on. This will positively -affect the number of available .onion nodes. - -This new feature is enabled by default if Bitcoin Core is listening (`-listen`), and -requires a Tor connection to work. It can be explicitly disabled with `-listenonion=0` -and, if not disabled, configured using the `-torcontrol` and `-torpassword` settings. -To show verbose debugging information, pass `-debug=tor`. - -Connecting to Tor's control socket API requires one of two authentication methods to be -configured. It also requires the control socket to be enabled, e.g. put `ControlPort 9051` -in `torrc` config file. For cookie authentication the user running bitcoind must have read -access to the `CookieAuthFile` specified in Tor configuration. In some cases this is -preconfigured and the creation of an onion service is automatic. If permission problems -are seen with `-debug=tor` they can be resolved by adding both the user running Tor and -the user running bitcoind to the same group and setting permissions appropriately. On -Debian-based systems the user running bitcoind can be added to the debian-tor group, -which has the appropriate permissions. Before starting bitcoind you will need to re-login -to allow debian-tor group to be applied. Otherwise you will see the following notice: "tor: -Authentication cookie /run/tor/control.authcookie could not be opened (check permissions)" -on debug.log. - -An alternative authentication method is the use -of the `-torpassword=password` option. The `password` is the clear text form that -was used when generating the hashed password for the `HashedControlPassword` option -in the tor configuration file. The hashed password can be obtained with the command -`tor --hash-password password` (read the tor manual for more details). - ## 4. Privacy recommendations -- Do not add anything but Bitcoin Core ports to the onion service created in section 2. +- Do not add anything but Bitcoin Core ports to the onion service created in section 3. If you run a web service too, create a new onion service for that. Otherwise it is trivial to link them, which may reduce privacy. Onion - services created automatically (as in section 3) always have only one port + services created automatically (as in section 2) always have only one port open. |