Installing GNUnet
*****************

This guide is intended for those who want to install Gnunet from source. For instructions on how to install GNUnet as a binary package please refer to the official documentation of your operating system or package manager.

Installing dependencies
=======================

GNUnet needs few libraries and applications for being able to run and another few optional ones for using certain features. Preferably they should be installed with a package manager. Just in case we include a link to the project websites.

The mandatory libraries and applications are

  * libtool

  * autoconf ≥2.59

  * automake ≥1.11.1

  * pkg-config

  * libgcrypt ≥1.6

  * libextractor

  * libidn

  * libmicrohttpd ≥0.9.52

  * libnss

  * libunistring

  * gettext

  * glibc

  * libgmp

  * gnutls

  * libcurl (has to be linked to GnuTLS) or libgnurl

  * zlib

In addition GNUnet needs one of of these three databases

  * sqlite + libsqlite (the default, requires no further configuration)

  * postgres + libpq

  * mysql + libmysqlclient

These are the dependencies only required for certain features

  * Texinfo (for building the documentation)

  * Texlive (for building the documentation)

  * miniupnpc (for traversing NAT boxes more reliably)

  * libopus (for running the GNUnet conversation telephony application)

  * libpulse (for running the GNUnet conversation telephony application)

  * libogg (for running the GNUnet conversation telephony application)

  * bluez (for bluetooth support)

  * libpbc (for attribute-based encryption and the identity provider subsystem)

  * libgabe (for attribute-based encryption and the identity provider subsystem)

Getting the Source Code
=======================

You can either download the source code using git (you obviously need git installed) or as an archive.

Using git type

     git clone https://git.gnunet.org/gnunet.git

The archive can be found at https://ftpmirror.gnu.org/gnu/gnunet/. Extract it using a graphical archive tool or tar:

     tar xzvf gnunet-0.11.0pre66.tar.gz

In the next chapter we will assume that the source code is available in the home directory at ~/gnunet.

Create gnunet user and group
============================

The GNUnet services should be run as a dedicated user called gnunet. For using them a user should be in the same group as this system user.

Create user gnunet who is member of the group gnunet and specify a home directory where the GNUnet services will store persistant data such as information about peers.

     $ sudo useradd --system --groups gnunet --home-dir /var/lib/gnunet

Now add your own user to the gnunet group.

     $ sudo adduser alice gnunet

Preparing and Compiling the Source Code
=======================================

For preparing the source code for compilation a bootstrap script and configure has to be run from the source code directory. When running configure the following options can be specified to customize the compilation and installation process:

  * --disable-documentation - don't build the configuration documents

  * --enable-looging=[LOGLEVEL] - choose a loglevel (debug, info, warning or error)

  * --prefix=[PATH] - the directory where the GNUnet libraries and binaries will be installed

  * --with-extractor=[PATH] - the path to libextractor

  * --with-libidn=[PATH] - the path to libidn

  * --with-microhttpd=[PATH] - the path to libmicrohttpd

  * --with-sqlite=[PATH] - the path to libsqlite

  * --with-zlib=[PATH] - the path to zlib

  * --with-sudo=[PATH] - path to the sudo binary (no need to run make install as root if specified)

The following example configures the installation prefix /usr/lib and disables building the documentation

     $ cd ~/gnunet
     $ ./bootstrap
     $ configure --prefix=/usr/lib --disable-configuration

After running the bootstrap script and configure successfully the source code can be compiled with make. Here -j5 specifies that 5 threads should be used.

     $ make -j5

Installation
============

The compiled binaries can be installed using make install. It needs to be run as root (or with sudo) because some binaries need the suid bit set. Without that some GNUnet subsystems (such as VPN) will not work.

     $ sudo make install

One important library is the GNS plugin for NSS (the name services switch) which allows using GNS (the GNU name system) in the normal DNS resolution process. Unfortunately NSS expects it in a specific location (probably /lib) which may differ from the installation prefix (see --prefix option in the previous section). This is why the pugin has to be installed manually.

Find the directory where nss plugins are installed on your system, e.g.

     $ ls -l /lib/libnss_*
     /lib/libnss_mymachines.so.2
     /lib/libnss_resolve.so.2
     /lib/libnss_myhostname.so.2
     /lib/libnss_systemd.so.2

Copy the GNS NSS plugin to that directory:

     cp ~/gnunet/src/gns/nss/libnss_gns.so.2 /lib

Now, to activate the plugin, you need to edit your /etc/nsswitch.conf where you should find a line like this:

     hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4

The exact details may differ a bit, which is fine. Add the text "gns [NOTFOUND=return]" after "files".

     hosts: files gns [NOTFOUND=return] mdns4_minimal [NOTFOUND=return] dns mdns4

Optionally, if GNS shall be used with a browser, execute the GNS CA-setup script. It will isetup the GNS Certificate Authority with the user's browser.

     $ gnunet-gns-proxy-setup-ca

Finally install a configuration file in ~/.gnunet/gnunet.conf. Below you find an example config which allows you to start GNUnet.

     [arm]
     SYSTEM_ONLY = NO
     USER_ONLY = NO

     [transport]
     PLUGINS = tcp

MOVED FROM USER Checking the Installation
=========================================

This section describes a quick, casual way to check if your GNUnet installation works. However, if it does not, we do not cover steps for recovery --- for this, please study the instructions provided in the developer handbook as well as the system-specific instruction in the source code repository. Please note that the system specific instructions are not provided as part of this handbook!.

gnunet-gtk
----------

The gnunet-gtk package contains several graphical user interfaces for the respective GNUnet applications. Currently these interfaces cover:

  * Statistics

  * Peer Information

  * GNU Name System

  * File Sharing

  * Identity Management

  * Conversation

Statistics
----------

We assume that you have started gnunet via gnunet-arm or via your system-provided method for starting services. First, you should launch GNUnet gtk. You can do this from the command-line by typing

     gnunet-statistics-gtk

If your peer is running correctly, you should see a bunch of lines, all of which should be ``significantly'' above zero (at least if your peer has been running for more than a few seconds). The lines indicate how many other peers your peer is connected to (via different mechanisms) and how large the entire overlay network is currently estimated to be. The X-axis represents time (in seconds since the start of gnunet-gtk).

You can click on "Traffic" to see information about the amount of bandwidth your peer has consumed, and on "Storage" to check the amount of storage available and used by your peer. Note that "Traffic" is plotted cumulatively, so you should see a strict upwards trend in the traffic.

The term ``peer'' is a common word used in federated and distributed networks to describe a participating device which is connected to the network. Thus, your Personal Computer or whatever it is you are looking at the Gtk+ interface describes a ``Peer'' or a ``Node''.

Peer Information
----------------

First, you should launch the graphical user interface.  You can do this from the command-line by typing

     $ gnunet-peerinfo-gtk

Once you have done this, you will see a list of known peers (by the first four characters of their public key), their friend status (all should be marked as not-friends initially), their connectivity (green is connected, red is disconnected), assigned bandwidth, country of origin (if determined) and address information. If hardly any peers are listed and/or if there are very few peers with a green light for connectivity, there is likely a problem with your network configuration.

MOVED FROM USER The graphical configuration interface
=====================================================

If you also would like to use gnunet-gtk and gnunet-setup (highly recommended for beginners), do:

Configuring your peer
---------------------

This chapter will describe the various configuration options in GNUnet.

The easiest way to configure your peer is to use the gnunet-setup tool. gnunet-setup is part of the gnunet-gtk application. You might have to install it separately.

Many of the specific sections from this chapter actually are linked from within gnunet-setup to help you while using the setup tool.

While you can also configure your peer by editing the configuration file by hand, this is not recommended for anyone except for developers as it requires a more in-depth understanding of the configuration files and internal dependencies of GNUnet.

Configuring the Friend-to-Friend (F2F) mode
-------------------------------------------

GNUnet knows three basic modes of operation:

  * In standard "peer-to-peer" mode, your peer will connect to any peer.

  * In the pure "friend-to-friend" mode, your peer will ONLY connect to peers from a list of friends specified in the configuration.

  * Finally, in mixed mode, GNUnet will only connect to arbitrary peers if it has at least a specified number of connections to friends.

When configuring any of the F2F ("friend-to-friend") modes, you first need to create a file with the peer identities of your friends. Ask your friends to run

     $ gnunet-peerinfo -sq

The resulting output of this command needs to be added to your friends file, which is simply a plain text file with one line per friend with the output from the above command.

You then specify the location of your friends file in the FRIENDS option of the "topology" section.

Once you have created the friends file, you can tell GNUnet to only connect to your friends by setting the FRIENDS-ONLY option (again in the "topology" section) to YES.

If you want to run in mixed-mode, set "FRIENDS-ONLY" to NO and configure a minimum number of friends to have (before connecting to arbitrary peers) under the "MINIMUM-FRIENDS" option.

If you want to operate in normal P2P-only mode, simply set MINIMUM-FRIENDS to zero and FRIENDS_ONLY to NO. This is the default.

Configuring the hostlist to bootstrap
-------------------------------------

After installing the software you need to get connected to the GNUnet network. The configuration file included in your download is already configured to connect you to the GNUnet network. In this section the relevant configuration settings are explained.

To get an initial connection to the GNUnet network and to get to know peers already connected to the network you can use the so called "bootstrap servers". These servers can give you a list of peers connected to the network. To use these bootstrap servers you have to configure the hostlist daemon to activate bootstrapping.

To activate bootstrapping, edit the [hostlist]-section in your configuration file. You have to set the argument -b in the options line:

     [hostlist]
     OPTIONS = -b

Additionally you have to specify which server you want to use. The default bootstrapping server is "http://v10.gnunet.org/hostlist". [^] To set the server you have to edit the line "SERVERS" in the hostlist section. To use the default server you should set the lines to

     SERVERS = http://v10.gnunet.org/hostlist [^]

To use bootstrapping your configuration file should include these lines:

     [hostlist]
     OPTIONS = -b
     SERVERS = http://v10.gnunet.org/hostlist [^]

Besides using bootstrap servers you can configure your GNUnet peer to receive hostlist advertisements. Peers offering hostlists to other peers can send advertisement messages to peers that connect to them. If you configure your peer to receive these messages, your peer can download these lists and connect to the peers included. These lists are persistent, which means that they are saved to your hard disk regularly and are loaded during startup.

To activate hostlist learning you have to add the -e switch to the OPTIONS line in the hostlist section:

     [hostlist]
     OPTIONS = -b -e

Furthermore you can specify in which file the lists are saved. To save the lists in the file hostlists.file just add the line:

     HOSTLISTFILE = hostlists.file

Best practice is to activate both bootstrapping and hostlist learning. So your configuration file should include these lines:

     [hostlist]
     OPTIONS = -b -e
     HTTPPORT = 8080
     SERVERS = http://v10.gnunet.org/hostlist [^]
     HOSTLISTFILE = $SERVICEHOME/hostlists.file

Configuration of the HOSTLIST proxy settings
--------------------------------------------

The hostlist client can be configured to use a proxy to connect to the hostlist server. This functionality can be configured in the configuration file directly or using the gnunet-setup tool.

The hostlist client supports the following proxy types at the moment:

  * HTTP and HTTP 1.0 only proxy

  * SOCKS 4/4a/5/5 with hostname

In addition authentication at the proxy with username and password can be configured.

To configure proxy support for the hostlist client in the gnunet-setup tool, select the "hostlist" tab and select the appropriate proxy type. The hostname or IP address (including port if required) has to be entered in the "Proxy hostname" textbox. If required, enter username and password in the "Proxy username" and "Proxy password" boxes. Be aware that this information will be stored in the configuration in plain text (TODO: Add explanation and generalize the part in Chapter 3.6 about the encrypted home).

To provide these options directly in the configuration, you can enter the following settings in the [hostlist] section of the configuration:

     # Type of proxy server,
     # Valid values: HTTP, HTTP_1_0, SOCKS4, SOCKS5, SOCKS4A, SOCKS5_HOSTNAME
     # Default: HTTP
     # PROXY_TYPE = HTTP

     # Hostname or IP of proxy server
     # PROXY =
     # User name for proxy server
     # PROXY_USERNAME =
     # User password for proxy server
     # PROXY_PASSWORD =

Configuring your peer to provide a hostlist
-------------------------------------------

If you operate a peer permanently connected to GNUnet you can configure your peer to act as a hostlist server, providing other peers the list of peers known to him.

Your server can act as a bootstrap server and peers needing to obtain a list of peers can contact it to download this list. To download this hostlist the peer uses HTTP. For this reason you have to build your peer with libgnurl (or libcurl) and microhttpd support.

To configure your peer to act as a bootstrap server you have to add the -p option to OPTIONS in the [hostlist] section of your configuration file. Besides that you have to specify a port number for the http server. In conclusion you have to add the following lines:

     [hostlist]
     HTTPPORT = 12980
     OPTIONS = -p

If your peer acts as a bootstrap server other peers should know about that. You can advertise the hostlist your are providing to other peers. Peers connecting to your peer will get a message containing an advertisement for your hostlist and the URL where it can be downloaded. If this peer is in learning mode, it will test the hostlist and, in the case it can obtain the list successfully, it will save it for bootstrapping.

To activate hostlist advertisement on your peer, you have to set the following lines in your configuration file:

     [hostlist]
     EXTERNAL_DNS_NAME = example.org
     HTTPPORT = 12981
     OPTIONS = -p -a

With this configuration your peer will a act as a bootstrap server and advertise this hostlist to other peers connecting to it. The URL used to download the list will be http://example.org:12981/.

Please notice:

  * The hostlist is not human readable, so you should not try to download it using your webbrowser. Just point your GNUnet peer to the address!

  * Advertising without providing a hostlist does not make sense and will not work.

Configuring the datastore
-------------------------

The datastore is what GNUnet uses for long-term storage of file-sharing data. Note that long-term does not mean 'forever' since content does have an expiration date, and of course storage space is finite (and hence sometimes content may have to be discarded).

Use the QUOTA option to specify how many bytes of storage space you are willing to dedicate to GNUnet.

In addition to specifying the maximum space GNUnet is allowed to use for the datastore, you need to specify which database GNUnet should use to do so. Currently, you have the choice between sqLite, MySQL and Postgres.

Configuring the MySQL database
------------------------------

This section describes how to setup the MySQL database for GNUnet.

Note that the mysql plugin does NOT work with mysql before 4.1 since we need prepared statements. We are generally testing the code against MySQL 5.1 at this point.

Reasons for using MySQL
-----------------------

  * On up-to-date hardware wher mysql can be used comfortably, this module will have better performance than the other database choices (according to our tests).

  * Its often possible to recover the mysql database from internal inconsistencies. Some of the other databases do not support repair.

Reasons for not using MySQL
---------------------------

  * Memory usage (likely not an issue if you have more than 1 GB)

  * Complex manual setup

Setup Instructions
------------------

  * In gnunet.conf set in section DATASTORE the value for DATABASE to mysql.

  * Access mysql as root:

          $ mysql -u root -p

     and issue the following commands, replacing $USER with the username that will be running gnunet-arm (so typically "gnunet"):

          CREATE DATABASE gnunet;
          GRANT select,insert,update,delete,create,alter,drop,create \
          temporary tables ON gnunet.* TO $USER@localhost;
          SET PASSWORD FOR $USER@localhost=PASSWORD('$the_password_you_like');
          FLUSH PRIVILEGES;

  * In the $HOME directory of $USER, create a .my.cnf file with the following lines

          [client]
          user=$USER
          password=$the_password_you_like

That's it. Note that .my.cnf file is a slight security risk unless its on a safe partition. The $HOME/.my.cnf can of course be a symbolic link. Luckily $USER has only privileges to mess up GNUnet's tables, which should be pretty harmless.

Testing
-------

You should briefly try if the database connection works. First, login as $USER. Then use:

     $ mysql -u $USER
     mysql> use gnunet;

If you get the message

     Database changed

it probably works.

If you get

     ERROR 2002: Can't connect to local MySQL server
     through socket '/tmp/mysql.sock' (2)

it may be resolvable by

     ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock

so there may be some additional trouble depending on your mysql setup.

Performance Tuning
------------------

For GNUnet, you probably want to set the option

     innodb_flush_log_at_trx_commit = 0

for a rather dramatic boost in MySQL performance. However, this reduces the "safety" of your database as with this options you may loose transactions during a power outage. While this is totally harmless for GNUnet, the option applies to all applications using MySQL. So you should set it if (and only if) GNUnet is the only application on your system using MySQL.

Setup for running Testcases
---------------------------

If you want to run the testcases, you must create a second database "gnunetcheck" with the same username and password. This database will then be used for testing (make check).

Configuring the Postgres database
---------------------------------

This text describes how to setup the Postgres database for GNUnet.

This Postgres plugin was developed for Postgres 8.3 but might work for earlier versions as well.

Reasons to use Postgres
-----------------------

  * Easier to setup than MySQL

  * Real database

Reasons not to use Postgres
---------------------------

  * Quite slow

  * Still some manual setup required

Manual setup instructions
-------------------------

  * In gnunet.conf set in section DATASTORE the value for DATABASE to postgres.

  * Access Postgres to create a user:

     with Postgres 8.x, use:

               # su - postgres
               $ createuser

          and enter the name of the user running GNUnet for the role interactively. Then, when prompted, do not set it to superuser, allow the creation of databases, and do not allow the creation of new roles.

     with Postgres 9.x, use:

               # su - postgres
               $ createuser -d $GNUNET_USER

          where $GNUNET_USER is the name of the user running GNUnet.

  * As that user (so typically as user "gnunet"), create a database (or two):

          $ createdb gnunet
          # this way you can run "make check"
          $ createdb gnunetcheck

Now you should be able to start gnunet-arm.

Testing the setup manually
--------------------------

You may want to try if the database connection works. First, again login as the user who will run gnunet-arm. Then use:

     $ psql gnunet # or gnunetcheck
     gnunet=> \dt

If, after you have started gnunet-arm at least once, you get a gn090 table here, it probably works.

Configuring the datacache
-------------------------

The datacache is what GNUnet uses for storing temporary data. This data is expected to be wiped completely each time GNUnet is restarted (or the system is rebooted).

You need to specify how many bytes GNUnet is allowed to use for the datacache using the QUOTA option in the section [dhtcache]. Furthermore, you need to specify which database backend should be used to store the data. Currently, you have the choice between sqLite, MySQL and Postgres.

Configuring the file-sharing service
------------------------------------

In order to use GNUnet for file-sharing, you first need to make sure that the file-sharing service is loaded. This is done by setting the START_ON_DEMAND option in section [fs] to "YES". Alternatively, you can run

     $ gnunet-arm -i fs

to start the file-sharing service by hand.

Except for configuring the database and the datacache the only important option for file-sharing is content migration.

Content migration allows your peer to cache content from other peers as well as send out content stored on your system without explicit requests. This content replication has positive and negative impacts on both system performance and privacy.

FIXME: discuss the trade-offs. Here is some older text about it...

Setting this option to YES allows gnunetd to migrate data to the local machine. Setting this option to YES is highly recommended for efficiency. Its also the default. If you set this value to YES, GNUnet will store content on your machine that you cannot decrypt. While this may protect you from liability if the judge is sane, it may not (IANAL). If you put illegal content on your machine yourself, setting this option to YES will probably increase your chances to get away with it since you can plausibly deny that you inserted the content. Note that in either case, your anonymity would have to be broken first (which may be possible depending on the size of the GNUnet network and the strength of the adversary).

Configuring logging
-------------------

Logging in GNUnet 0.9.0 is controlled via the "-L" and "-l" options. Using -L, a log level can be specified. With log level ERROR only serious errors are logged. The default log level is WARNING which causes anything of concern to be logged. Log level INFO can be used to log anything that might be interesting information whereas DEBUG can be used by developers to log debugging messages (but you need to run ./configure with --enable-logging=verbose to get them compiled). The -l option is used to specify the log file.

Since most GNUnet services are managed by gnunet-arm, using the -l or -L options directly is not possible. Instead, they can be specified using the OPTIONS configuration value in the respective section for the respective service. In order to enable logging globally without editing the OPTIONS values for each service, gnunet-arm supports a GLOBAL_POSTFIX option. The value specified here is given as an extra option to all services for which the configuration does contain a service-specific OPTIONS field.

GLOBAL_POSTFIX can contain the special sequence "{}" which is replaced by the name of the service that is being started. Furthermore, GLOBAL_POSTFIX is special in that sequences starting with "$" anywhere in the string are expanded (according to options in PATHS); this expansion otherwise is only happening for filenames and then the "$" must be the first character in the option. Both of these restrictions do not apply to GLOBAL_POSTFIX. Note that specifying % anywhere in the GLOBAL_POSTFIX disables both of these features.

In summary, in order to get all services to log at level INFO to log-files called SERVICENAME-logs, the following global prefix should be used:

     GLOBAL_POSTFIX = -l $SERVICEHOME/{}-logs -L INFO

Configuring the transport service and plugins
---------------------------------------------

The transport service in GNUnet is responsible to maintain basic connectivity to other peers. Besides initiating and keeping connections alive it is also responsible for address validation.

The GNUnet transport supports more than one transport protocol. These protocols are configured together with the transport service.

The configuration section for the transport service itself is quite similar to all the other services

     START_ON_DEMAND = YES
     @UNIXONLY@ PORT = 2091
     HOSTNAME = localhost
     HOME = $SERVICEHOME
     CONFIG = $DEFAULTCONFIG
     BINARY = gnunet-service-transport
     #PREFIX = valgrind
     NEIGHBOUR_LIMIT = 50
     ACCEPT_FROM = 127.0.0.1;
     ACCEPT_FROM6 = ::1;
     PLUGINS = tcp udp
     UNIXPATH = /tmp/gnunet-service-transport.sock

Different are the settings for the plugins to load PLUGINS. The first setting specifies which transport plugins to load.

  * transport-unix A plugin for local only communication with UNIX domain sockets. Used for testing and available on unix systems only. Just set the port

          [transport-unix]
          PORT = 22086
          TESTING_IGNORE_KEYS = ACCEPT_FROM;

  * transport-tcp A plugin for communication with TCP. Set port to 0 for client mode with outbound only connections

          [transport-tcp]
          # Use 0 to ONLY advertise as a peer behind NAT (no port binding)
          PORT = 2086
          ADVERTISED_PORT = 2086
          TESTING_IGNORE_KEYS = ACCEPT_FROM;
          # Maximum number of open TCP connections allowed
          MAX_CONNECTIONS = 128

  * transport-udp A plugin for communication with UDP. Supports peer discovery using broadcasts.

          [transport-udp]
          PORT = 2086
          BROADCAST = YES
          BROADCAST_INTERVAL = 30 s
          MAX_BPS = 1000000
          TESTING_IGNORE_KEYS = ACCEPT_FROM;

  * transport-http HTTP and HTTPS support is split in two part: a client plugin initiating outbound connections and a server part accepting connections from the client. The client plugin just takes the maximum number of connections as an argument.

          [transport-http_client]
          MAX_CONNECTIONS = 128
          TESTING_IGNORE_KEYS = ACCEPT_FROM;

          [transport-https_client]
          MAX_CONNECTIONS = 128
          TESTING_IGNORE_KEYS = ACCEPT_FROM;

     The server has a port configured and the maximum number of connections. The HTTPS part has two files with the certificate key and the certificate file.

     The server plugin supports reverse proxies, so a external hostname can be set using the EXTERNAL_HOSTNAME setting. The webserver under this address should forward the request to the peer and the configure port.

          [transport-http_server]
          EXTERNAL_HOSTNAME = fulcrum.net.in.tum.de/gnunet
          PORT = 1080
          MAX_CONNECTIONS = 128
          TESTING_IGNORE_KEYS = ACCEPT_FROM;

          [transport-https_server]
          PORT = 4433
          CRYPTO_INIT = NORMAL
          KEY_FILE = https.key
          CERT_FILE = https.cert
          MAX_CONNECTIONS = 128
          TESTING_IGNORE_KEYS = ACCEPT_FROM;

  * transport-wlan

     The next section describes how to setup the WLAN plugin, so here only the settings. Just specify the interface to use:

          [transport-wlan]
          # Name of the interface in monitor mode (typically monX)
          INTERFACE = mon0
          # Real hardware, no testing
          TESTMODE = 0
          TESTING_IGNORE_KEYS = ACCEPT_FROM;

Configuring the WLAN transport plugin
-------------------------------------

The wlan transport plugin enables GNUnet to send and to receive data on a wlan interface. It has not to be connected to a wlan network as long as sender and receiver are on the same channel. This enables you to get connection to GNUnet where no internet access is possible, for example during catastrophes or when censorship cuts you off from the internet.

Requirements for the WLAN plugin
................................

  * wlan network card with monitor support and packet injection (see aircrack-ng.org (http://www.aircrack-ng.org/))

  * Linux kernel with mac80211 stack, introduced in 2.6.22, tested with 2.6.35 and 2.6.38

  * Wlantools to create the a monitor interface, tested with airmon-ng of the aircrack-ng package

Configuration
.............

There are the following options for the wlan plugin (they should be like this in your default config file, you only need to adjust them if the values are incorrect for your system)

     # section for the wlan transport plugin
     [transport-wlan]
     # interface to use, more information in the
     # "Before starting GNUnet" section of the handbook.
     INTERFACE = mon0
     # testmode for developers:
     # 0 use wlan interface,
     #1 or 2 use loopback driver for tests 1 = server, 2 = client
     TESTMODE = 0

Before starting GNUnet
......................

Before starting GNUnet, you have to make sure that your wlan interface is in monitor mode. One way to put the wlan interface into monitor mode (if your interface name is wlan0) is by executing:

     sudo airmon-ng start wlan0

Here is an example what the result should look like:

     Interface Chipset Driver
     wlan0 Intel 4965 a/b/g/n iwl4965 - [phy0]
     (monitor mode enabled on mon0)

The monitor interface is mon0 is the one that you have to put into the configuration file.

Limitations and known bugs
..........................

Wlan speed is at the maximum of 1 Mbit/s because support for choosing the wlan speed with packet injection was removed in newer kernels. Please pester the kernel developers about fixing this.

The interface channel depends on the wlan network that the card is connected to. If no connection has been made since the start of the computer, it is usually the first channel of the card. Peers will only find each other and communicate if they are on the same channel. Channels must be set manually, i.e. using:

     iwconfig wlan0 channel 1

Configuring HTTP(S) reverse proxy functionality using Apache or nginx
---------------------------------------------------------------------

The HTTP plugin supports data transfer using reverse proxies. A reverse proxy forwards the HTTP request he receives with a certain URL to another webserver, here a GNUnet peer.

So if you have a running Apache or nginx webserver you can configure it to be a GNUnet reverse proxy. Especially if you have a well-known webiste this improves censorship resistance since it looks as normal surfing behaviour.

To do so, you have to do two things:

  * Configure your webserver to forward the GNUnet HTTP traffic

  * Configure your GNUnet peer to announce the respective address

As an example we want to use GNUnet peer running:

  * HTTP server plugin on gnunet.foo.org:1080

  * HTTPS server plugin on gnunet.foo.org:4433

  * A apache or nginx webserver on http://www.foo.org:80/ (http://www.foo.org/)

  * A apache or nginx webserver on https://www.foo.org:443/

And we want the webserver to accept GNUnet traffic under http://www.foo.org/bar/. The required steps are described here:

Reverse Proxy - Configure your Apache2 HTTP webserver
.....................................................

First of all you need mod_proxy installed.

Edit your webserver configuration. Edit /etc/apache2/apache2.conf or the site-specific configuration file.

In the respective server config,virtual host or directory section add the following lines:

     ProxyTimeout 300
     ProxyRequests Off
     <Location /bar/ >
     ProxyPass http://gnunet.foo.org:1080/
     ProxyPassReverse http://gnunet.foo.org:1080/
     </Location>

Reverse Proxy - Configure your Apache2 HTTPS webserver
......................................................

We assume that you already have an HTTPS server running, if not please check how to configure a HTTPS host. An uncomplicated to use example is the example configuration file for Apache2/HTTPD provided in apache2/sites-available/default-ssl.

In the respective HTTPS server config,virtual host or directory section add the following lines:

     SSLProxyEngine On
     ProxyTimeout 300
     ProxyRequests Off
     <Location /bar/ >
     ProxyPass https://gnunet.foo.org:4433/
     ProxyPassReverse https://gnunet.foo.org:4433/
     </Location>

More information about the apache mod_proxy configuration can be found in the Apache documentation (http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass).

Reverse Proxy - Configure your nginx HTTPS webserver
....................................................

Since nginx does not support chunked encoding, you first of all have to install the chunkin module (http://wiki.nginx.org/HttpChunkinModule).

To enable chunkin add:

     chunkin on;
     error_page 411 = @my_411_error;
     location @my_411_error {
     chunkin_resume;
     }

Edit your webserver configuration. Edit /etc/nginx/nginx.conf or the site-specific configuration file.

In the server section add:

     location /bar/ {
     proxy_pass http://gnunet.foo.org:1080/;
     proxy_buffering off;
     proxy_connect_timeout 5; # more than http_server
     proxy_read_timeout 350; # 60 default, 300s is GNUnet's idle timeout
     proxy_http_version 1.1; # 1.0 default
     proxy_next_upstream error timeout invalid_header http_500 http_503 http_502 http_504;
     }

Reverse Proxy - Configure your nginx HTTP webserver
...................................................

Edit your webserver configuration. Edit /etc/nginx/nginx.conf or the site-specific configuration file.

In the server section add:

     ssl_session_timeout 6m;
     location /bar/
     {
     proxy_pass https://gnunet.foo.org:4433/;
     proxy_buffering off;
     proxy_connect_timeout 5; # more than http_server
     proxy_read_timeout 350; # 60 default, 300s is GNUnet's idle timeout
     proxy_http_version 1.1; # 1.0 default
     proxy_next_upstream error timeout invalid_header http_500 http_503 http_502 http_504;
     }

Reverse Proxy - Configure your GNUnet peer
..........................................

To have your GNUnet peer announce the address, you have to specify the EXTERNAL_HOSTNAME option in the [transport-http_server] section:

     [transport-http_server]
     EXTERNAL_HOSTNAME = http://www.foo.org/bar/

and/or [transport-https_server] section:

     [transport-https_server]
     EXTERNAL_HOSTNAME = https://www.foo.org/bar/

Now restart your webserver and your peer...

Blacklisting peers
------------------

Transport service supports to deny connecting to a specific peer of to a specific peer with a specific transport plugin using te blacklisting component of transport service. With blacklisting it is possible to deny connections to specific peers of to use a specific plugin to a specific peer. Peers can be blacklisted using the configuration or a blacklist client can be asked.

To blacklist peers using the configuration you have to add a section to your configuration containing the peer id of the peer to blacklist and the plugin if required.

Examples:

To blacklist connections to P565... on peer AG2P... using tcp add:

     [transport-blacklist AG2PHES1BARB9IJCPAMJTFPVJ5V3A72S3F2A8SBUB8DAQ2V0O3V8G6G2JU56FHGFOHMQVKBSQFV98TCGTC3RJ1NINP82G0RC00N1520]
     P565723JO1C2HSN6J29TAQ22MN6CI8HTMUU55T0FUQG4CMDGGEQ8UCNBKUMB94GC8R9G4FB2SF9LDOBAJ6AMINBP4JHHDD6L7VD801G = tcp

To blacklist connections to P565... on peer AG2P... using all plugins add:

     [transport-blacklist-AG2PHES1BARB9IJCPAMJTFPVJ5V3A72S3F2A8SBUB8DAQ2V0O3V8G6G2JU56FHGFOHMQVKBSQFV98TCGTC3RJ1NINP82G0RC00N1520]
     P565723JO1C2HSN6J29TAQ22MN6CI8HTMUU55T0FUQG4CMDGGEQ8UCNBKUMB94GC8R9G4FB2SF9LDOBAJ6AMINBP4JHHDD6L7VD801G =

You can also add a blacklist client usign the blacklist API. On a blacklist check, blacklisting first checks internally if the peer is blacklisted and if not, it asks the blacklisting clients. Clients are asked if it is OK to connect to a peer ID, the plugin is omitted.

On blacklist check for (peer, plugin)

  * Do we have a local blacklist entry for this peer and this plugin?

  * YES: disallow connection

  * Do we have a local blacklist entry for this peer and all plugins?

  * YES: disallow connection

  * Does one of the clients disallow?

  * YES: disallow connection

Configuration of the HTTP and HTTPS transport plugins
-----------------------------------------------------

The client parts of the http and https transport plugins can be configured to use a proxy to connect to the hostlist server. This functionality can be configured in the configuration file directly or using the gnunet-setup tool.

Both the HTTP and HTTPS clients support the following proxy types at the moment:

  * HTTP 1.1 proxy

  * SOCKS 4/4a/5/5 with hostname

In addition authentication at the proxy with username and password can be configured.

To configure proxy support for the clients in the gnunet-setup tool, select the "transport" tab and activate the respective plugin. Now you can select the appropriate proxy type. The hostname or IP address (including port if required) has to be entered in the "Proxy hostname" textbox. If required, enter username and password in the "Proxy username" and "Proxy password" boxes. Be aware that these information will be stored in the configuration in plain text.

To configure these options directly in the configuration, you can configure the following settings in the [transport-http_client] and [transport-https_client] section of the configuration:

     # Type of proxy server,
     # Valid values: HTTP, SOCKS4, SOCKS5, SOCKS4A, SOCKS5_HOSTNAME
     # Default: HTTP
     # PROXY_TYPE = HTTP

     # Hostname or IP of proxy server
     # PROXY =
     # User name for proxy server
     # PROXY_USERNAME =
     # User password for proxy server
     # PROXY_PASSWORD =

Configuring the GNU Name System
-------------------------------

Configuring system-wide DNS interception
........................................

Before you install GNUnet, make sure you have a user and group 'gnunet' as well as an empty group 'gnunetdns'.

When using GNUnet with system-wide DNS interception, it is absolutely necessary for all GNUnet service processes to be started by gnunet-service-arm as user and group 'gnunet'. You also need to be sure to run make install as root (or use the sudo option to configure) to grant GNUnet sufficient privileges.

With this setup, all that is required for enabling system-wide DNS interception is for some GNUnet component (VPN or GNS) to request it. The gnunet-service-dns will then start helper programs that will make the necessary changes to your firewall (iptables) rules.

Note that this will NOT work if your system sends out DNS traffic to a link-local IPv6 address, as in this case GNUnet can intercept the traffic, but not inject the responses from the link-local IPv6 address. Hence you cannot use system-wide DNS interception in conjunction with link-local IPv6-based DNS servers. If such a DNS server is used, it will bypass GNUnet's DNS traffic interception.

Using the GNU Name System (GNS) requires two different configuration steps. First of all, GNS needs to be integrated with the operating system. Most of this section is about the operating system level integration.

The remainder of this chapter will detail the various methods for configuring the use of GNS with your operating system.

At this point in time you have different options depending on your OS:

  * Use the gnunet-gns-proxy
     This approach works for all operating systems and is likely the easiest. However, it enables GNS only for browsers, not for other applications that might be using DNS, such as SSH.  Still, using the proxy is required for using HTTP with GNS and is thus recommended for all users. To do this, you simply have to run the gnunet-gns-proxy-setup-ca script as the user who will run the browser (this will create a GNS certificate authority (CA) on your system and import its key into your browser), then start gnunet-gns-proxy and inform your browser to use the Socks5 proxy which gnunet-gns-proxy makes available by default on port 7777.

  * Use a nsswitch plugin (recommended on GNU systems)
     This approach has the advantage of offering fully personalized resolution even on multi-user systems. A potential disadvantage is that some applications might be able to bypass GNS.

  * Use a W32 resolver plugin (recommended on W32)
     This is currently the only option on W32 systems.

  * Use system-wide DNS packet interception
     This approach is recommended for the GNUnet VPN. It can be used to handle GNS at the same time; however, if you only use this method, you will only get one root zone per machine (not so great for multi-user systems).

You can combine system-wide DNS packet interception with the nsswitch plugin. The setup of the system-wide DNS interception is described here. All of the other GNS-specific configuration steps are described in the following sections.

Configuring the GNS nsswitch plugin
...................................

The Name Service Switch (NSS) is a facility in Unix-like operating systems (in most cases provided by the GNU C Library) that provides a variety of sources for common configuration databases and name resolution mechanisms. A superuser (system administrator) usually configures the operating system's name services using the file /etc/nsswitch.conf.

GNS provides a NSS plugin to integrate GNS name resolution with the operating system's name resolution process. To use the GNS NSS plugin you have to either

  * install GNUnet as root or

  * compile GNUnet with the --with-sudo=yes switch.

Name resolution is controlled by the hosts section in the NSS configuration. By default this section first performs a lookup in the /etc/hosts file and then in DNS. The nsswitch file should contain a line similar to:

     hosts: files dns [NOTFOUND=return] mdns4_minimal mdns4

Here the GNS NSS plugin can be added to perform a GNS lookup before performing a DNS lookup. The GNS NSS plugin has to be added to the "hosts" section in /etc/nsswitch.conf file before DNS related plugins:

     ...
     hosts: files gns [NOTFOUND=return] dns mdns4_minimal mdns4
     ...

The NOTFOUND=return will ensure that if a .gnu name is not found in GNS it will not be queried in DNS.

Configuring GNS on W32
......................

This document is a guide to configuring GNU Name System on W32-compatible platforms.

After GNUnet is installed, run the w32nsp-install tool:

     w32nsp-install.exe libw32nsp-0.dll

('0' is the library version of W32 NSP; it might increase in the future, change the invocation accordingly).

This will install GNS namespace provider into the system and allow other applications to resolve names that end in 'gnu' and 'zkey'. Note that namespace provider requires gnunet-gns-helper-service-w32 to be running, as well as gns service itself (and its usual dependencies).

Namespace provider is hardcoded to connect to 127.0.0.1:5353, and this is where gnunet-gns-helper-service-w32 should be listening to (and is configured to listen to by default).

To uninstall the provider, run:

     w32nsp-uninstall.exe

(uses provider GUID to uninstall it, does not need a dll name).

Note that while MSDN claims that other applications will only be able to use the new namespace provider after re-starting, in reality they might stat to use it without that. Conversely, they might stop using the provider after it's been uninstalled, even if they were not re-started. W32 will not permit namespace provider library to be deleted or overwritten while the provider is installed, and while there is at least one process still using it (even after it was uninstalled).

GNS Proxy Setup
...............

When using the GNU Name System (GNS) to browse the WWW, there are several issues that can be solved by adding the GNS Proxy to your setup:

  * If the target website does not support GNS, it might assume that it is operating under some name in the legacy DNS system (such as example.com). It may then attempt to set cookies for that domain, and the web server might expect a Host: example.com header in the request from your browser. However, your browser might be using example.gnu for the Host header and might only accept (and send) cookies for example.gnu. The GNS Proxy will perform the necessary translations of the hostnames for cookies and HTTP headers (using the LEHO record for the target domain as the desired substitute).

  * If using HTTPS, the target site might include an SSL certificate which is either only valid for the LEHO domain or might match a TLSA record in GNS. However, your browser would expect a valid certificate for example.gnu, not for some legacy domain name. The proxy will validate the certificate (either against LEHO or TLSA) and then on-the-fly produce a valid certificate for the exchange, signed by your own CA. Assuming you installed the CA of your proxy in your browser's certificate authority list, your browser will then trust the HTTPS/SSL/TLS connection, as the hostname mismatch is hidden by the proxy.

  * Finally, the proxy will in the future indicate to the server that it speaks GNS, which will enable server operators to deliver GNS-enabled web sites to your browser (and continue to deliver legacy links to legacy browsers)

Setup of the GNS CA
...................

First you need to create a CA certificate that the proxy can use. To do so use the provided script gnunet-gns-proxy-ca:

     $ gnunet-gns-proxy-setup-ca

This will create a personal certification authority for you and add this authority to the firefox and chrome database. The proxy will use the this CA certificate to generate *.gnu client certificates on the fly.

Note that the proxy uses libcurl. Make sure your version of libcurl uses GnuTLS and NOT OpenSSL. The proxy will not work with libcurl compiled against OpenSSL.

You can check the configuration your libcurl was build with by running:

     curl --version

the output will look like this (without the linebreaks):

     gnurl --version
     curl 7.56.0 (x86_64-unknown-linux-gnu) libcurl/7.56.0 \
     GnuTLS/3.5.13 zlib/1.2.11 libidn2/2.0.4
     Release-Date: 2017-10-08
     Protocols: http https
     Features: AsynchDNS IDN IPv6 Largefile NTLM SSL libz \
     TLS-SRP UnixSockets HTTPS-proxy

Testing the GNS setup
.....................

Now for testing purposes we can create some records in our zone to test the SSL functionality of the proxy:

     $ gnunet-identity -C test
     $ gnunet-namestore -a -e "1 d" -n "homepage" \
       -t A -V 131.159.74.67 -z test
     $ gnunet-namestore -a -e "1 d" -n "homepage" \
       -t LEHO -V "gnunet.org" -z test

At this point we can start the proxy. Simply execute

     $ gnunet-gns-proxy

Configure your browser to use this SOCKSv5 proxy on port 7777 and visit this link. If you use Firefox (or one of its derivatives/forks such as Icecat) you also have to go to about:config and set the key network.proxy.socks_remote_dns to true.

When you visit https://homepage.test/, you should get to the https://gnunet.org/ frontpage and the browser (with the correctly configured proxy) should give you a valid SSL certificate for homepage.gnu and no warnings. It should look like this:

Migrating existing DNS zones into GNS
.....................................

To migrate an existing zone into GNS use the Ascension tool.

Ascension transfers entire zones into GNS by doing incremental zone transfers and then adding the records to GNS.

Compared to the gnunet-zoneimport tool it strictly uses AXFR or IXFR depending on whether or not there exists a SOA record for the zone. If that is the case it will take the serial as a reference point and request the zone. The server will either answer the IXFR request with a correct incremental zone or with the entire zone, which depends on the server configuration.

You can find the source code here: https://git.gnunet.org/ascension.git/

The software can be installed into a Python virtual environment like this:

     $ python3 -m venv .venv
     $ source .venv/bin/activate
     $ python3 setup.py install

Or installed globally like this:

     $ sudo python3 setup.py install

Pip will then install all the necessary requirements that are needed to run Ascension. For development purposes a virtual environment should suffice. Keeping a virtual environment helps with keeping things tidy and prevents breaking of Ascension through a future Python update.

The advantage of using a virtual environment is, that all the dependencies can be installed separately in different versions without touching your system Python installation and its dependencies.

See Migrating an existing DNS zone into GNS, for usage manual of the tool.

Configuring the GNUnet VPN
--------------------------

Before configuring the GNUnet VPN, please make sure that system-wide DNS interception is configured properly as described in the section on the GNUnet DNS setup. see Configuring the GNU Name System, if you haven't done so already.

The default options for the GNUnet VPN are usually sufficient to use GNUnet as a Layer 2 for your Internet connection. However, what you always have to specify is which IP protocol you want to tunnel: IPv4, IPv6 or both. Furthermore, if you tunnel both, you most likely should also tunnel all of your DNS requests. You theoretically can tunnel "only" your DNS traffic, but that usually makes little sense.

The other options as shown on the gnunet-setup tool are:

IPv4 address for interface
..........................

This is the IPv4 address the VPN interface will get. You should pick an 'private' IPv4 network that is not yet in use for you system. For example, if you use 10.0.0.1/255.255.0.0 already, you might use 10.1.0.1/255.255.0.0. If you use 10.0.0.1/255.0.0.0 already, then you might use 192.168.0.1/255.255.0.0. If your system is not in a private IP-network, using any of the above will work fine. You should try to make the mask of the address big enough (255.255.0.0 or, even better, 255.0.0.0) to allow more mappings of remote IP Addresses into this range. However, even a 255.255.255.0 mask will suffice for most users.

IPv6 address for interface
..........................

The IPv6 address the VPN interface will get. Here you can specify any non-link-local address (the address should not begin with fe80:). A subnet Unique Local Unicast (fd00::/8 prefix) that you are currently not using would be a good choice.

Configuring the GNUnet VPN DNS
..............................

To resolve names for remote nodes, activate the DNS exit option.

Configuring the GNUnet VPN Exit Service
.......................................

If you want to allow other users to share your Internet connection (yes, this may be dangerous, just as running a Tor exit node) or want to provide access to services on your host (this should be less dangerous, as long as those services are secure), you have to enable the GNUnet exit daemon.

You then get to specify which exit functions you want to provide. By enabling the exit daemon, you will always automatically provide exit functions for manually configured local services (this component of the system is under development and not documented further at this time). As for those services you explicitly specify the target IP address and port, there is no significant security risk in doing so.

Furthermore, you can serve as a DNS, IPv4 or IPv6 exit to the Internet. Being a DNS exit is usually pretty harmless. However, enabling IPv4 or IPv6-exit without further precautions may enable adversaries to access your local network, send spam, attack other systems from your Internet connection and to other mischief that will appear to come from your machine. This may or may not get you into legal trouble. If you want to allow IPv4 or IPv6-exit functionality, you should strongly consider adding additional firewall rules manually to protect your local network and to restrict outgoing TCP traffic (i.e. by not allowing access to port 25). While we plan to improve exit-filtering in the future, you're currently on your own here. Essentially, be prepared for any kind of IP-traffic to exit the respective TUN interface (and GNUnet will enable IP-forwarding and NAT for the interface automatically).

Additional configuration options of the exit as shown by the gnunet-setup tool are:

IP Address of external DNS resolver
...................................

If DNS traffic is to exit your machine, it will be send to this DNS resolver. You can specify an IPv4 or IPv6 address.

IPv4 address for Exit interface
...............................

This is the IPv4 address the Interface will get. Make the mask of the address big enough (255.255.0.0 or, even better, 255.0.0.0) to allow more mappings of IP addresses into this range. As for the VPN interface, any unused, private IPv4 address range will do.

IPv6 address for Exit interface
...............................

The public IPv6 address the interface will get. If your kernel is not a very recent kernel and you are willing to manually enable IPv6-NAT, the IPv6 address you specify here must be a globally routed IPv6 address of your host.

Suppose your host has the address 2001:4ca0::1234/64, then using 2001:4ca0::1:0/112 would be fine (keep the first 64 bits, then change at least one bit in the range before the bitmask, in the example above we changed bit 111 from 0 to 1).

You may also have to configure your router to route traffic for the entire subnet (2001:4ca0::1:0/112 for example) through your computer (this should be automatic with IPv6, but obviously anything can be disabled).

Bandwidth Configuration
-----------------------

You can specify how many bandwidth GNUnet is allowed to use to receive and send data. This is important for users with limited bandwidth or traffic volume.

Configuring NAT
---------------

Most hosts today do not have a normal global IP address but instead are behind a router performing Network Address Translation (NAT) which assigns each host in the local network a private IP address. As a result, these machines cannot trivially receive inbound connections from the Internet. GNUnet supports NAT traversal to enable these machines to receive incoming connections from other peers despite their limitations.

In an ideal world, you can press the "Attempt automatic configuration" button in gnunet-setup to automatically configure your peer correctly. Alternatively, your distribution might have already triggered this automatic configuration during the installation process. However, automatic configuration can fail to determine the optimal settings, resulting in your peer either not receiving as many connections as possible, or in the worst case it not connecting to the network at all.

To manually configure the peer, you need to know a few things about your network setup. First, determine if you are behind a NAT in the first place. This is always the case if your IP address starts with "10.*" or "192.168.*". Next, if you have control over your NAT router, you may choose to manually configure it to allow GNUnet traffic to your host. If you have configured your NAT to forward traffic on ports 2086 (and possibly 1080) to your host, you can check the "NAT ports have been opened manually" option, which corresponds to the "PUNCHED_NAT" option in the configuration file. If you did not punch your NAT box, it may still be configured to support UPnP, which allows GNUnet to automatically configure it. In that case, you need to install the "upnpc" command, enable UPnP (or PMP) on your NAT box and set the "Enable NAT traversal via UPnP or PMP" option (corresponding to "ENABLE_UPNP" in the configuration file).

Some NAT boxes can be traversed using the autonomous NAT traversal method. This requires certain GNUnet components to be installed with "SUID" privileges on your system (so if you're installing on a system you do not have administrative rights to, this will not work). If you installed as 'root', you can enable autonomous NAT traversal by checking the "Enable NAT traversal using ICMP method". The ICMP method requires a way to determine your NAT's external (global) IP address. This can be done using either UPnP, DynDNS, or by manual configuration. If you have a DynDNS name or know your external IP address, you should enter that name under "External (public) IPv4 address" (which corresponds to the "EXTERNAL_ADDRESS" option in the configuration file). If you leave the option empty, GNUnet will try to determine your external IP address automatically (which may fail, in which case autonomous NAT traversal will then not work).

Finally, if you yourself are not behind NAT but want to be able to connect to NATed peers using autonomous NAT traversal, you need to check the "Enable connecting to NATed peers using ICMP method" box.

Peer configuration for distributions
------------------------------------

The "GNUNET_DATA_HOME" in "[path]" in /etc/gnunet.conf should be manually set to "/var/lib/gnunet/data/" as the default "~/.local/share/gnunet/" is probably not that appropriate in this case. Similarly, distributions may consider pointing "GNUNET_RUNTIME_DIR" to "/var/run/gnunet/" and "GNUNET_HOME" to "/var/lib/gnunet/". Also, should a distribution decide to override system defaults, all of these changes should be done in a custom /etc/gnunet.conf and not in the files in the config.d/ directory.

Given the proposed access permissions, the "gnunet-setup" tool must be run as use "gnunet" (and with option "-c /etc/gnunet.conf" so that it modifies the system configuration). As always, gnunet-setup should be run after the GNUnet peer was stopped using "gnunet-arm -e". Distributions might want to include a wrapper for gnunet-setup that allows the desktop-user to "sudo" (i.e. using gtksudo) to the "gnunet" user account and then runs "gnunet-arm -e", "gnunet-setup" and "gnunet-arm -s" in sequence.

MOVED FROM USER Config Leftovers
================================

This section describes how to start a GNUnet peer. It assumes that you have already compiled and installed GNUnet and its' dependencies. Before you start a GNUnet peer, you may want to create a configuration file using gnunet-setup (but you do not have to). Sane defaults should exist in your $GNUNET_PREFIX/share/gnunet/config.d/ directory, so in practice you could simply start without any configuration. If you want to configure your peer later, you need to stop it before invoking the gnunet-setup tool to customize further and to test your configuration (gnunet-setup has build-in test functions).

The most important option you might have to still set by hand is in [PATHS]. Here, you use the option "GNUNET_HOME" to specify the path where GNUnet should store its data. It defaults to $HOME/, which again should work for most users. Make sure that the directory specified as GNUNET_HOME is writable to the user that you will use to run GNUnet (note that you can run frontends using other users, GNUNET_HOME must only be accessible to the user used to run the background processes).

You will also need to make one central decision: should all of GNUnet be run under your normal UID, or do you want distinguish between system-wide (user-independent) GNUnet services and personal GNUnet services. The multi-user setup is slightly more complicated, but also more secure and generally recommended.

The Single-User Setup
---------------------

For the single-user setup, you do not need to do anything special and can just start the GNUnet background processes using gnunet-arm. By default, GNUnet looks in ~/.config/gnunet.conf for a configuration (or $XDG_CONFIG_HOME/gnunet.conf if $XDG_CONFIG_HOME is defined). If your configuration lives elsewhere, you need to pass the -c FILENAME option to all GNUnet commands.

Assuming the configuration file is called ~/.config/gnunet.conf, you start your peer using the gnunet-arm command (say as user gnunet) using:

     gnunet-arm -c ~/.config/gnunet.conf -s

The "-s" option here is for "start". The command should return almost instantly. If you want to stop GNUnet, you can use:

     gnunet-arm -c ~/.config/gnunet.conf -e

The "-e" option here is for "end".

Note that this will only start the basic peer, no actual applications will be available. If you want to start the file-sharing service, use (after starting GNUnet):

     gnunet-arm -c ~/.config/gnunet.conf -i fs

The "-i fs" option here is for "initialize" the "fs" (file-sharing) application. You can also selectively kill only file-sharing support using

     gnunet-arm -c ~/.config/gnunet.conf -k fs

Assuming that you want certain services (like file-sharing) to be always automatically started whenever you start GNUnet, you can activate them by setting "IMMEDIATE_START=YES" in the respective section of the configuration file (for example, "[fs]"). Then GNUnet with file-sharing support would be started whenever you enter:

     gnunet-arm -c ~/.config/gnunet.conf -s

Alternatively, you can combine the two options:

     gnunet-arm -c ~/.config/gnunet.conf -s -i fs

Using gnunet-arm is also the preferred method for initializing GNUnet from init.

Finally, you should edit your crontab (using the crontab command) and insert a line

     @reboot gnunet-arm -c ~/.config/gnunet.conf -s

to automatically start your peer whenever your system boots.

The Multi-User Setup
--------------------

This requires you to create a user gnunet and an additional group gnunetdns, prior to running make install during installation. Then, you create a configuration file /etc/gnunet.conf which should contain the lines:

     [arm]
     START_SYSTEM_SERVICES = YES
     START_USER_SERVICES = NO

Then, perform the same steps to run GNUnet as in the per-user configuration, except as user gnunet (including the crontab installation). You may also want to run gnunet-setup to configure your peer (databases, etc.). Make sure to pass -c /etc/gnunet.conf to all commands. If you run gnunet-setup as user gnunet, you might need to change permissions on /etc/gnunet.conf so that the gnunet user can write to the file (during setup).

Afterwards, you need to perform another setup step for each normal user account from which you want to access GNUnet. First, grant the normal user ($USER) permission to the group gnunet:

     # adduser $USER gnunet

Then, create a configuration file in ~/.config/gnunet.conf for the $USER with the lines:

     [arm]
     START_SYSTEM_SERVICES = NO
     START_USER_SERVICES = YES

This will ensure that gnunet-arm when started by the normal user will only run services that are per-user, and otherwise rely on the system-wide services. Note that the normal user may run gnunet-setup, but the configuration would be ineffective as the system-wide services will use /etc/gnunet.conf and ignore options set by individual users.

Again, each user should then start the peer using gnunet-arm -s --- and strongly consider adding logic to start the peer automatically to their crontab.

Afterwards, you should see two (or more, if you have more than one USER) gnunet-service-arm processes running in your system.

Killing GNUnet services
-----------------------

It is not necessary to stop GNUnet services explicitly when shutting down your computer.

It should be noted that manually killing "most" of the gnunet-service processes is generally not a successful method for stopping a peer (since gnunet-service-arm will instantly restart them). The best way to explicitly stop a peer is using gnunet-arm -e; note that the per-user services may need to be terminated before the system-wide services will terminate normally.

Access Control for GNUnet
-------------------------

This chapter documents how we plan to make access control work within the GNUnet system for a typical peer. It should be read as a best-practice installation guide for advanced users and builders of binary distributions. The recommendations in this guide apply to POSIX-systems with full support for UNIX domain sockets only.

Note that this is an advanced topic. The discussion presumes a very good understanding of users, groups and file permissions. Normal users on hosts with just a single user can just install GNUnet under their own account (and possibly allow the installer to use SUDO to grant additional permissions for special GNUnet tools that need additional rights). The discussion below largely applies to installations where multiple users share a system and to installations where the best possible security is paramount.

A typical GNUnet system consists of components that fall into four categories:

User interfaces
     User interfaces are not security sensitive and are supposed to be run and used by normal system users. The GTK GUIs and most command-line programs fall into this category. Some command-line tools (like gnunet-transport) should be excluded as they offer low-level access that normal users should not need.

System services and support tools
     System services should always run and offer services that can then be accessed by the normal users. System services do not require special permissions, but as they are not specific to a particular user, they probably should not run as a particular user. Also, there should typically only be one GNUnet peer per host. System services include the gnunet-service and gnunet-daemon programs; support tools include command-line programs such as gnunet-arm.

Privileged helpers
     Some GNUnet components require root rights to open raw sockets or perform other special operations. These gnunet-helper binaries are typically installed SUID and run from services or daemons.

Critical services
     Some GNUnet services (such as the DNS service) can manipulate the service in deep and possibly highly security sensitive ways. For example, the DNS service can be used to intercept and alter any DNS query originating from the local machine. Access to the APIs of these critical services and their privileged helpers must be tightly controlled.

Recommendation - Disable access to services via TCP
...................................................

GNUnet services allow two types of access: via TCP socket or via UNIX domain socket. If the service is available via TCP, access control can only be implemented by restricting connections to a particular range of IP addresses. This is acceptable for non-critical services that are supposed to be available to all users on the local system or local network. However, as TCP is generally less efficient and it is rarely the case that a single GNUnet peer is supposed to serve an entire local network, the default configuration should disable TCP access to all GNUnet services on systems with support for UNIX domain sockets. As of GNUnet 0.9.2, configuration files with TCP access disabled should be generated by default. Users can re-enable TCP access to particular services simply by specifying a non-zero port number in the section of the respective service.

Recommendation - Run most services as system user "gnunet"
..........................................................

GNUnet's main services should be run as a separate user "gnunet" in a special group "gnunet". The user "gnunet" should start the peer using "gnunet-arm -s" during system startup. The home directory for this user should be /var/lib/gnunet and the configuration file should be /etc/gnunet.conf. Only the gnunet user should have the right to access /var/lib/gnunet (mode: 700).

Recommendation - Control access to services using group "gnunet"
................................................................

Users that should be allowed to use the GNUnet peer should be added to the group "gnunet". Using GNUnet's access control mechanism for UNIX domain sockets, those services that are considered useful to ordinary users should be made available by setting "UNIX_MATCH_GID=YES" for those services. Again, as shipped, GNUnet provides reasonable defaults. Permissions to access the transport and core subsystems might additionally be granted without necessarily causing security concerns. Some services, such as DNS, must NOT be made accessible to the "gnunet" group (and should thus only be accessible to the "gnunet" user and services running with this UID).

Recommendation - Limit access to certain SUID binaries by group "gnunet"
........................................................................

Most of GNUnet's SUID binaries should be safe even if executed by normal users. However, it is possible to reduce the risk a little bit more by making these binaries owned by the group "gnunet" and restricting their execution to user of the group "gnunet" as well (4750).

Recommendation - Limit access to critical gnunet-helper-dns to group "gnunetdns"
................................................................................

A special group "gnunetdns" should be created for controlling access to the "gnunet-helper-dns". The binary should then be owned by root and be in group "gnunetdns" and be installed SUID and only be group-executable (2750). Note that the group "gnunetdns" should have no users in it at all, ever. The "gnunet-service-dns" program should be executed by user "gnunet" (via gnunet-service-arm) with the binary owned by the user "root" and the group "gnunetdns" and be SGID (2700). This way, only "gnunet-service-dns" can change its group to "gnunetdns" and execute the helper, and the helper can then run as root (as per SUID). Access to the API offered by "gnunet-service-dns" is in turn restricted to the user "gnunet" (not the group!), which means that only "benign" services can manipulate DNS queries using "gnunet-service-dns".

Differences between "make install" and these recommendations
............................................................

The current build system does not set all permissions automatically based on the recommendations above. In particular, it does not use the group "gnunet" at all (so setting gnunet-helpers other than the gnunet-helper-dns to be owned by group "gnunet" must be done manually). Furthermore, 'make install' will silently fail to set the DNS binaries to be owned by group "gnunetdns" unless that group already exists (!). An alternative name for the "gnunetdns" group can be specified using the --with-gnunetdns=GRPNAME configure option.