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diff --git a/doc/tor.md b/doc/tor.md index e70c2ebd64..c72f16de5e 100644 --- a/doc/tor.md +++ b/doc/tor.md @@ -117,37 +117,94 @@ for normal IPv4/IPv6 communication, use: ## 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). +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. + +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). ## 4. Privacy recommendations |