merge bitcoin#20757: tor.md and -onlynet help updates

doc/tor.md

@@ -16,14 +16,19 @@ 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
+	                to manually configure an onion service (see section 3), you'll
-	                it explicitly.
+	                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
@@ -33,7 +38,11 @@ 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.
 
 An example how to start the client if the Tor proxy is running on local host on
 port 9050 and only allows .onion nodes to connect:
@@ -44,8 +53,99 @@ In a typical situation, this suffices to run behind a Tor proxy:
 
 	./dashd -proxy=127.0.0.1:9050
 
+## 2. Automatically create a Dash Core onion service
 
-## 2. Run a Dash Core hidden server
+Dash 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, Dash 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 Dash 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 dashd 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 dashd's `-torpassword`
+configuration option.
+
+#### Cookie authentication
+
+For cookie authentication, the user running dashd 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` dashd 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
+dashd 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 dashd, 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
+dashd.
+
+#### `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 Dash Core onion service
 
 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
@@ -101,7 +201,7 @@ for normal IPv4/IPv6 communication, use:
 	./dashd -onion=127.0.0.1:9050 -externalip=ssapp53tmftyjmjb.onion -discover
 
 
-## 3. List of known Dash Core Tor relays
+## 3.1. List of known Dash Core Tor relays
 
 Note: All these nodes are hosted by masternodehosting.com
 
@@ -116,45 +216,10 @@ Note: All these nodes are hosted by masternodehosting.com
 * ys5upbdeotplam3y.onion
 * fijy6aikzxfea54i.onion
 
+## 4. Privacy recommendations
 
-## 4. Automatically listen on Tor
+- Do not add anything but Dash Core ports to the onion service created in section 3.
-
-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.
-Dash Core has been updated to make use of this.
-
-This means that if Tor is running (and proper authentication has been configured),
-Dash Core automatically creates a onion service to listen on. This will positively
-affect the number of available .onion nodes.
-
-This new feature is enabled by default if Dash 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 dashd 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 dashd to the same group and setting permissions appropriately. On
-Debian-based systems the user running dashd can be added to the debian-tor group,
-which has the appropriate permissions. Before starting dashd 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).
-
-## 5. Privacy recommendations
-
-- Do not add anything but Dash Core ports to the onion service created in section 2.
   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.

src/init.cpp

@@ -580,7 +580,7 @@ void SetupServerArgs(NodeContext& node)
     argsman.AddArg("-maxtimeadjustment", strprintf("Maximum allowed median peer time offset adjustment. Local perspective of time may be influenced by peers forward or backward by this amount. (default: %u seconds)", DEFAULT_MAX_TIME_ADJUSTMENT), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-maxuploadtarget=<n>", strprintf("Tries to keep outbound traffic under the given target (in MiB per 24h). Limit does not apply to peers with 'download' permission. 0 = no limit (default: %d)", DEFAULT_MAX_UPLOAD_TARGET), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-onion=<ip:port>", "Use separate SOCKS5 proxy to reach peers via Tor onion services, set -noonion to disable (default: -proxy)", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
-    argsman.AddArg("-onlynet=<net>", "Make outgoing connections only through network <net> (ipv4, ipv6 or onion). Incoming connections are not affected by this option. This option can be specified multiple times to allow multiple networks.", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
+    argsman.AddArg("-onlynet=<net>", "Make outgoing connections only through network <net> (ipv4, ipv6 or onion). Incoming connections are not affected by this option. This option can be specified multiple times to allow multiple networks. Warning: if it is used with ipv4 or ipv6 but not onion and the -onion or -proxy option is set, then outbound onion connections will still be made; use -noonion or -onion=0 to disable outbound onion connections in this case.", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-peerblockfilters", strprintf("Serve compact block filters to peers per BIP 157 (default: %u)", DEFAULT_PEERBLOCKFILTERS), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-peerbloomfilters", strprintf("Support filtering of blocks and transaction with bloom filters (default: %u)", DEFAULT_PEERBLOOMFILTERS), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-peertimeout=<n>", strprintf("Specify p2p connection timeout in seconds. This option determines the amount of time a peer may be inactive before the connection to it is dropped. (minimum: 1, default: %d)", DEFAULT_PEER_CONNECT_TIMEOUT), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);