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# TOR SUPPORT IN PIVX

It is possible to run PIVX Core as a Tor hidden service, and connect to such services.
It is possible to run PIVX Core as a Tor onion service, and connect to such services.

The following directions assume you have a Tor proxy running on port 9050. Many distributions default to having a SOCKS proxy listening on port 9050, but others may not. In particular, the Tor Browser Bundle defaults to listening on port 9150. See [Tor Project FAQ:TBBSocksPort](https://www.torproject.org/docs/faq.html.en#TBBSocksPort) for how to properly
configure Tor.

## Compatibility

- Starting with version 5.3.0, PIVX Core only supports Tor version 3 hidden
services (Tor v3). Tor v2 addresses are ignored by PIVX Core and neither
relayed nor stored.

- Tor removed v2 support beginning with version 0.4.6.

## How to see information about your Tor configuration via PIVX Core

There are several ways to see your local onion address in PIVX Core:
- in the debug log (grep for "tor:" or "AddLocal")
- in the output of RPC `getnetworkinfo` in the "localaddresses" section
- in the output of the CLI `-netinfo` peer connections dashboard

You may set the `-debug=tor` config logging option to have additional
information in the debug log about your Tor configuration.

CLI `-addrinfo` returns the number of addresses known to your node per network
type, including Tor v2 and v3. This is useful to see how many onion addresses
are known to your node for `-onlynet=onion` and how many Tor v3 addresses it
knows when upgrading to PIVX Core v5.3.0 and up that supports Tor v3 only.

## 1. Run PIVX Core behind a Tor proxy
----------------------------------

The first step is running PIVX behind a Tor proxy. This will already anonymize all
The first step is running PIVX Core behind a Tor proxy. This will already anonymize all
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.
-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 -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 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
-seednode=X SOCKS5. In Tor mode, such addresses can also be exchanged with
other P2P nodes.

-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. 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:

-onion=ip:port Set the proxy server to use for Tor hidden services. You do not
need to set this if it's the same as -proxy. You can use -noonion
to explicitly disable access to hidden services.
./pivxd -proxy=127.0.0.1:9050

-listen When using -proxy, listening is disabled by default. If you want
to run a hidden service (see next section), you'll need to enable
it explicitly.
## 2. Automatically create a PIVX Core onion service

-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
-seednode=X SOCKS5. In Tor mode, such addresses can also be exchanged with
other P2P nodes.
PIVX 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, PIVX Core automatically creates an
onion service to listen on. The goal is to increase the number of available
onion nodes.

-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.
This feature is enabled by default if PIVX 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.

In a typical situation, this suffices to run behind a Tor proxy:
To see verbose Tor information in the pivxd 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 pivxd's `-torpassword`
configuration option.

#### Cookie authentication

./pivxd -proxy=127.0.0.1:9050
For cookie authentication, the user running pivxd 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` pivxd 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
pivxd to the same Tor group and setting permissions appropriately.

## 2. Run a PIVX Core hidden server
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:

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).*
```
getent group | cut -d: -f1 | grep -i tor
```

HiddenServiceDir /var/lib/tor/pivx-service/
HiddenServiceVersion 2
HiddenServicePort 51472 127.0.0.1:51472
HiddenServicePort 61472 127.0.0.1:61472
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`:

The directory can be different of course, but (both) port numbers should be equal to
your pivxd's P2P listen port (51472 by default).
```
stat -c '%G' /run/tor/control.authcookie
```

-externalip=X You can tell pivx about its publicly reachable address using
this option, and this can be a v2 .onion address (v3 .onion
addresses are not supported by the PIVX network). Given the above
configuration, you can find your .onion address in
/var/lib/tor/pivx-service/hostname. For connections
coming from unroutable addresses (such as 127.0.0.1, where the
Tor proxy typically runs), .onion addresses are given
preference for your node to advertise itself with.
Once you have determined the `${TORGROUP}` and selected the `${USER}` that will
run pivxd, run this as root:

-listen You'll need to enable listening for incoming connections, as this
is off by default behind a proxy.
```
usermod -a -G ${TORGROUP} ${USER}
```

-discover When -externalip is specified, no attempt is made to discover local
IPv4 or IPv6 addresses. If you want to run a dual stack, reachable
from both Tor and IPv4 (or IPv6), you'll need to either pass your
other addresses using -externalip, or explicitly enable -discover.
Note that both addresses of a dual-stack system may be easily
linkable using traffic analysis.
Then restart the computer (or log out) and log in as the `${USER}` that will run
pivxd.

#### `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 PIVX 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/pivx-service/
HiddenServicePort 51472 127.0.0.1:51472

The directory can be different of course, but virtual port numbers should be equal to
your pivxd's P2P listen port (51472 by default), and target addresses and ports
should be equal to binding address and port for inbound Tor connections (127.0.0.1:51472 by default).

-externalip=X You can tell pivx about its publicly reachable addresses using
this option, and this can be an onion address. Given the above
configuration, you can find your onion address in
/var/lib/tor/pivx-service/hostname. For connections
coming from unroutable addresses (such as 127.0.0.1, where the
Tor proxy typically runs), onion addresses are given
preference for your node to advertise itself with.

You can set multiple local addresses with -externalip. The
one that will be rumoured to a particular peer is the most
compatible one and also using heuristics, e.g. the address
with the most incoming connections, etc.

-listen You'll need to enable listening for incoming connections, as this
is off by default behind a proxy.

-discover When -externalip is specified, no attempt is made to discover local
IPv4 or IPv6 addresses. If you want to run a dual stack, reachable
from both Tor and IPv4 (or IPv6), you'll need to either pass your
other addresses using -externalip, or explicitly enable -discover.
Note that both addresses of a dual-stack system may be easily
linkable using traffic analysis.

In a typical situation, where you're only reachable via Tor, this should suffice:

./pivxd -proxy=127.0.0.1:9050 -externalip=pivxzj6l4cvo2fxy.onion -listen
./pivxd -proxy=127.0.0.1:9050 -externalip=7zvj7a2imdgkdbg4f2dryd5rgtrn7upivr5eeij4cicjh65pooxeshid.onion -listen

(obviously, replace the .onion address with your own). It should be noted that you still
listen on all devices and another node could establish a clearnet connection, when knowing
your address. To mitigate this, additionally bind the address of your Tor proxy:

./pivxd ... -bind=127.0.0.1
./pivxd ... -bind=127.0.0.1

If you don't care too much about hiding your node, and want to be reachable on IPv4
as well, use `discover` instead:

./pivxd ... -discover
./pivxd ... -discover

and open port 51472 on your firewall (or use port mapping, i.e., `-upnp` or `-natpmp`).

If you only want to use Tor to reach .onion addresses, but not use it as a proxy
for normal IPv4/IPv6 communication, use:

./pivxd -onion=127.0.0.1:9050 -externalip=pivxzj6l4cvo2fxy.onion -discover

## 3. Automatically listen on Tor

Starting with Tor version 0.2.7.1 it is possible, through Tor's control socket
API, to create and destroy 'ephemeral' hidden services programmatically.
PIVX Core has been updated to make use of this.

This means that if Tor is running (and proper authentication has been configured),
PIVX Core automatically creates a hidden service to listen on. This will positively
affect the number of available .onion nodes.

This new feature is enabled by default if PIVX 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 pivxd must have read
access to the `CookieAuthFile` specified in Tor configuration. In some cases this is
preconfigured and the creation of a hidden 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 pivxd to the same group and setting permissions appropriately. On
Debian-based systems the user running pivxd can be added to the debian-tor group,
which has the appropriate permissions.

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).
./pivxd -onion=127.0.0.1:9050 -externalip=7zvj7a2imdgkdbg4f2dryd5rgtrn7upivr5eeij4cicjh65pooxeshid.onion -discover

## 4. Privacy recommendations

- Do not add anything but PIVX Core ports to the hidden service created in section 2.
If you run a web service too, create a new hidden service for that.
Otherwise it is trivial to link them, which may reduce privacy. Hidden
services created automatically (as in section 3) always have only one port
- Do not add anything but PIVX 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 2) always have only one port
open.

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