@node Installing GNUnet @chapter 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. For understanding this guide properly it is important to know that there are two different ways of running GNUnet: @itemize @bullet @item the @emph{single-user setup} @item the @emph{multi-user setup} @end itemize The latter variant has a better security model and requires extra preparation before running @code{make install} and a different configuration. Beginners who want to quickly try out GNUnet can use the @emph{single-user setup}. @menu * Installing dependencies:: * Getting the Source Code:: * Create user and groups for the system services:: * Preparing and Compiling the Source Code:: * Installation:: * Minimal configuration:: * Checking the Installation:: * The graphical configuration interface:: * Config Leftovers:: @end menu @c ----------------------------------------------------------------------- @node Installing dependencies @section 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. The mandatory libraries and applications are @itemize @bullet @item autoconf 2.59 or above @item automake 1.11.1 or above @item gettext @item glibc (read below, other libcs work) @item GnuTLS 3.2.12 or above, recommended to be linked against libunbound @item GNU make 4.0 or higher (other make implementations do work) @item iptables (on Linux systems) @item libtool 2.2 or above @item libltdl (part of libtool) @item libgcrypt 1.6 or above @item libidn2 or libidn @item libmicrohttpd 0.9.63 or above @item libunistring @item libgmp @item libgnurl or libcurl (libcurl has to be linked to GnuTLS) 7.35.0 or above @item Texinfo 5.2 or above (for building the documentation) @item Texlive 2012 or above (for building the documentation, and for gnunet-bcd) @item makeinfo 4.8 or above @item pkgconf (or pkg-config) @item zlib @end itemize Glibc is required for certain NSS features: @example One mechanism of integrating GNS with legacy applications via NSS is not available if this is disabled. But applications that don't use the glibc for NS resolution won't work anyway with this, so little is lost on *BSD systems. GNS via direct use or via the HTTP or DNS proxies is unaffected. @end example Other libcs should work, the resulting builds just don't include the glibc NSS specific code. One example is the build against NetBSD's libc as detailed in @uref{https://bugs.gnunet.org/view.php?id=5605}. In addition GNUnet needs at least one of these three databases (at the minimum sqlite3) @itemize @bullet @item sqlite + libsqlite 3.8 or above (the default, requires no further configuration) @item postgres + libpq @item mysql + libmysqlclient @end itemize These are the dependencies only required for certain features @itemize @bullet @item miniupnpc (for traversing NAT boxes more reliably) @item libnss @item libopus (for running the GNUnet conversation telephony application) @item libogg (for running the GNUnet conversation telephony application) @item gstreamer OR libpulse (for running the GNUnet conversation telephony application) @item bluez (for bluetooth support) @item libextractor (optional but highly recommended, read below) @item libpbc (for attribute-based encryption and the identity provider subsystem) @item libgabe (for attribute-based encryption and the identity provider subsystem) @item texi2mdoc (for automatic mdoc generation) @item perl5 for some utilities (which are not installed) @item libjanson @end itemize About libextractor being optional: @example While libextractor ("LE") is optional, it is recommended to build gnunet against it. If you install it later, you won't benefit from libextractor. If you are a distributor, we recommend to split LE into basis + plugins rather than making LE an option as an afterthought by the user. LE itself is very small, but its dependency chain on first, second, third etc level can be big. There is a small effect on privacy if your LE build differs from one which includes all plugins (plugins are build as shared objects): if users publish a directory with a mixture of file types (for example mpeg, jpeg, png, gif) the configuration of LE could leak which plugins are installed for which filetypes are not providing more details. However, this leak is just a minor concern. @end example These are the test-suite requirements: @itemize @bullet @item python3.6 or higher @item gnunet (installation first) @item some core-utils: which(1), bc(1), curl(1), sed(1), awk(1), etc. @item a shell (very few Bash scripts, the majority are POSIX sh scripts) @end itemize These are runtime requirements: @itemize @bullet @item nss (the certutil binary, for gnunet-gns-proxy-setup-ca) @item openssl (openssl binary, for gnunet-gns-proxy-setup-ca) @end itemize @c ----------------------------------------------------------------------- @node Getting the Source Code @section 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 @example git clone https://git.gnunet.org/gnunet.git @end example The archive can be found at @uref{https://ftpmirror.gnu.org/gnu/gnunet/}. Extract it using a graphical archive tool or @code{tar}: @example tar xzvf gnunet-@value{VERSION}.tar.gz @end example In the next chapter we will assume that the source code is available in the home directory at @code{~/gnunet}. @c ----------------------------------------------------------------------- @node Create user and groups for the system services @section Create user and groups for the system services @cartouche For the single-user setup this section can be skipped. @end cartouche The multi-user setup means that there are @emph{system services}, which are run once per machine as a dedicated system user (called @code{gnunet}) and @emph{user services} which can be started by every user who wants to use GNUnet applications. The user services communicate with the system services over unix domain sockets. To gain permissions to read and write those sockets the users running GNUnet applications will need to be in the @code{gnunet} group. In addition the group @code{gnunetdns} may be needed (see below). Create user @code{gnunet} who is member of the group @code{gnunet} (automatically created) and specify a home directory where the GNUnet services will store persistent data such as information about peers. @example $ sudo useradd --system --home-dir /var/lib/gnunet --create-home gnunet @end example Now add your own user to the @code{gnunet} group. @example $ sudo usermod -aG gnunet alice @end example Create a group @code{gnunetdns}. This allows using @code{setgid} in a way that only the DNS service can run the @code{gnunet-helper-dns} binary. This is only needed if @emph{system-wide DNS interception} will be used. For more information see @xref{Configuring system-wide DNS interception}. @example $ sudo groupadd gnunetdns @end example @c ----------------------------------------------------------------------- @node Preparing and Compiling the Source Code @section Preparing and Compiling the Source Code For preparing the source code for compilation a bootstrap script and @code{configure} has to be run from the source code directory. When running @code{configure} the following options can be specified to customize the compilation and installation process: @itemize @bullet @item @code{--disable-documentation} - don't build the documentation @item @code{--enable-logging=[LOGLEVEL]} - choose a loglevel (@code{debug}, @code{info}, @code{warning} or @code{error}) @item @code{--prefix=[PATH]} - the directory where the GNUnet libraries and binaries will be installed @item @code{--with-extractor=[PATH]} - the path to libextractor @item @code{--with-libidn=[PATH]} - the path to libidn @item @code{--with-libidn2=[PATH]} - the path to libidn2 (takes priority over libidn if both are found) @item @code{--with-microhttpd=[PATH]} - the path to libmicrohttpd @item @code{--with-sqlite=[PATH]} - the path to libsqlite @item @code{--with-zlib=[PATH]} - the path to zlib @end itemize Note that the list above is not always up to date and you should check the output of @code{./configure --help}, read the @file{configure.ac} or send an email asking for assistance if you are in doubt of any configure options or require fixes for your operating system. The following example configures the installation prefix @code{/usr/local} and disables building the documentation @example $ cd ~/gnunet $ ./bootstrap $ configure --prefix=/usr/local --disable-documentation @end example After running the bootstrap script and @code{configure} successfully the source code can be compiled with make. Here @code{-j5} specifies that 5 threads should be used. @example $ make -j5 @end example @c ----------------------------------------------------------------------- @node Installation @section Installation The compiled binaries can be installed using @code{make install}. It needs to be run as root (or with sudo) because some binaries need the @code{suid} bit set. Without that some features (e.g. the VPN service, system-wide DNS interception, NAT traversal using ICMP) will not work. @example $ sudo make install @end example @menu * NSS plugin (Optional):: * Installing the GNS Certificate Authority (Optional):: @end menu @node NSS plugin (Optional) @subsection NSS plugin (Optional) @cartouche The installation of the NSS plugin is only necessary if GNS resolution shall be used with legacy applications (that only support DNS). @end cartouche 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 @code{/lib}) which may differ from the installation prefix (see @code{--prefix} option in the previous section). This is why the plugin has to be installed manually. Find the directory where nss plugins are installed on your system, e.g. @example $ ls -l /lib/libnss_* /lib/libnss_mymachines.so.2 /lib/libnss_resolve.so.2 /lib/libnss_myhostname.so.2 /lib/libnss_systemd.so.2 @end example Copy the GNS NSS plugin to that directory: @example cp ~/gnunet/src/gns/nss/.libs/libnss_gns.so.2 /lib @end example Now, to activate the plugin, you need to edit your @code{/etc/nsswitch.conf} where you should find a line like this: @example hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4 @end example The exact details may differ a bit, which is fine. Add the text @code{"gns [NOTFOUND=return]"} after @code{"files"}. @example hosts: files gns [NOTFOUND=return] mdns4_minimal [NOTFOUND=return] dns mdns4 @end example @node Installing the GNS Certificate Authority (Optional) @subsection Installing the GNS Certificate Authority (Optional) @cartouche Installing the GNS certificate authority is only necessary if GNS shall be used in a browser. @end cartouche The GNS Certificate authority can provide TLS certificates for GNS names while downloading webpages from legacy webservers. This allows browsers to use HTTPS in combinations with GNS name resolution. To install it execute the GNS CA-setup script. So far Firefox and Chromium are supported. @example $ gnunet-gns-proxy-setup-ca @end example A local proxy server, that takes care of the name resolution and provides certificates on-the-fly needs to be started: @example $ /usr/lib/gnunet/libexec/gnunet-gns-proxy @end example Now GNS should work in browsers that are configured to use a SOCKS proxy on @code{localhost:7777}. @node Minimal configuration @section Minimal configuration GNUnet needs a configuration file to start (@pxref{Config file format}). For the @emph{single-user setup} an empty file is sufficient: @example $ touch ~/.config/gnunet.conf @end example For the @emph{multi-user setup} we need an extra config file for the system services. The default location is @code{/etc/gnunet.conf}. The minimal content of that file which activates the system services roll is: @example [arm] START_SYSTEM_SERVICES = YES START_USER_SERVICES = NO @end example The config file for the user services (@code{~/.config/gnunet.conf}) needs the opposite configuration to activate the user services roll: @example [arm] START_SYSTEM_SERVICES = NO START_USER_SERVICES = YES @end example @node Checking the Installation @section 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! @menu * Starting GNUnet:: * gnunet-gtk:: * Statistics:: * Peer Information:: @end menu @cindex Starting GNUnet @cindex GNUnet GTK @cindex GTK @cindex GTK user interface @node Starting GNUnet @subsection Starting GNUnet The GNUnet services are started and stopped by the ARM service (Automatic Restart Manager). For the @emph{single-user setup} a simple @example $ gnunet-arm -s @end example starts a default set of services. Later GNUnet applications can request more services to start without additional user interaction. GNUnet can be stopped again using the @code{-e} option: @example $ gnunet-arm -e @end example The list of running services can be displayed using the @code{-I} option. It should look similar to this example: @example $ gnunet-arm -I Running services: topology (gnunet-daemon-topology) nat (gnunet-service-nat) vpn (gnunet-service-vpn) gns (gnunet-service-gns) cadet (gnunet-service-cadet) namecache (gnunet-service-namecache) hostlist (gnunet-daemon-hostlist) revocation (gnunet-service-revocation) ats (gnunet-service-ats) peerinfo (gnunet-service-peerinfo) zonemaster (gnunet-service-zonemaster) zonemaster-monitor (gnunet-service-zonemaster-monitor) dht (gnunet-service-dht) namestore (gnunet-service-namestore) set (gnunet-service-set) statistics (gnunet-service-statistics) nse (gnunet-service-nse) fs (gnunet-service-fs) peerstore (gnunet-service-peerstore) core (gnunet-service-core) rest (gnunet-rest-server) transport (gnunet-service-transport) datastore (gnunet-service-datastore) @end example For the @emph{multi-user setup} first the system services need to be started as the system user, i.e. the user @code{gnunet} needs to execute @code{gnunet-arm -s}. This should be done by the system's init system. Then the user who wants to start GNUnet applications has to run @code{gnunet-arm -s} too. It is recommended to automate this, e.g. using the user's crontab. @node gnunet-gtk @subsection gnunet-gtk The @command{gnunet-gtk} package contains several graphical user interfaces for the respective GNUnet applications. Currently these interfaces cover: @itemize @bullet @item Statistics @item Peer Information @item GNU Name System @item File Sharing @item Conversation @item Setup @end itemize Previously, many of these interfaces were combined into one application called @command{gnunet-gtk}, with different tabs for each interface. This combined application has been removed in version 0.11.0, but each of the interfaces is still available as a standalone application (@command{gnunet-statistics-gtk} for statistics, @command{gnunet-fs-gtk} for filesharing, etc). @node Statistics @subsection Statistics We assume that you have started gnunet via @code{gnunet-arm} or via your system-provided method for starting services. First, you should launch GNUnet's graphical statistics interface. You can do this from the command-line by typing @example gnunet-statistics-gtk @end example 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 @command{gnunet-statistics-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''. @node Peer Information @subsection Peer Information First, you should launch the peer information graphical user interface. You can do this from the command-line by typing @example $ gnunet-peerinfo-gtk @end example 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. @c NOTE: Inserted from Installation Handbook in original ``order'': @c FIXME: Move this to User Handbook. @node The graphical configuration interface @section The graphical configuration interface If you also would like to use @command{gnunet-gtk} and @command{gnunet-setup} (highly recommended for beginners), do: @menu * Configuring your peer:: * Configuring the Friend-to-Friend (F2F) mode:: * Configuring the hostlist to bootstrap:: * Configuration of the HOSTLIST proxy settings:: * Configuring your peer to provide a hostlist :: * Configuring the datastore:: * Configuring the MySQL database:: * Reasons for using MySQL:: * Reasons for not using MySQL:: * Setup Instructions:: * Testing:: * Performance Tuning:: * Setup for running Testcases:: * Configuring the Postgres database:: * Reasons to use Postgres:: * Reasons not to use Postgres:: * Manual setup instructions:: * Testing the setup manually:: * Configuring the datacache:: * Configuring the file-sharing service:: * Configuring logging:: * Configuring the transport service and plugins:: * Configuring the WLAN transport plugin:: * Configuring HTTP(S) reverse proxy functionality using Apache or nginx:: * Blacklisting peers:: * Configuration of the HTTP and HTTPS transport plugins:: * Configuring the GNU Name System:: * Configuring the GNUnet VPN:: * Bandwidth Configuration:: * Configuring NAT:: * Peer configuration for distributors (e.g. Operating Systems):: @end menu @node Configuring your peer @subsection Configuring your peer This chapter will describe the various configuration options in GNUnet. The easiest way to configure your peer is to use the @command{gnunet-setup} tool. @command{gnunet-setup} is part of the @command{gnunet-gtk} package. You might have to install it separately. Many of the specific sections from this chapter actually are linked from within @command{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. @node Configuring the Friend-to-Friend (F2F) mode @subsection Configuring the Friend-to-Friend (F2F) mode GNUnet knows three basic modes of operation: @itemize @bullet @item In standard "peer-to-peer" mode, your peer will connect to any peer. @item In the pure "friend-to-friend" mode, your peer will ONLY connect to peers from a list of friends specified in the configuration. @item Finally, in mixed mode, GNUnet will only connect to arbitrary peers if it has at least a specified number of connections to friends. @end itemize 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 @example $ gnunet-peerinfo -sq @end example @noindent The resulting output of this command needs to be added to your @file{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 @file{friends} file in the @code{FRIENDS} option of the "topology" section. Once you have created the @file{friends} file, you can tell GNUnet to only connect to your friends by setting the @code{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 @code{MINIMUM-FRIENDS} to zero and @code{FRIENDS_ONLY} to NO. This is the default. @node Configuring the hostlist to bootstrap @subsection 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 @code{[hostlist]}-section in your configuration file. You have to set the argument @command{-b} in the options line: @example [hostlist] OPTIONS = -b @end example Additionally you have to specify which server you want to use. The default bootstrapping server is "@uref{http://v10.gnunet.org/hostlist, 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 @example SERVERS = http://v10.gnunet.org/hostlist [^] @end example @noindent To use bootstrapping your configuration file should include these lines: @example [hostlist] OPTIONS = -b SERVERS = http://v10.gnunet.org/hostlist [^] @end example @noindent 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 @command{-e} switch to the @code{OPTIONS} line in the hostlist section: @example [hostlist] OPTIONS = -b -e @end example @noindent Furthermore you can specify in which file the lists are saved. To save the lists in the file @file{hostlists.file} just add the line: @example HOSTLISTFILE = hostlists.file @end example @noindent Best practice is to activate both bootstrapping and hostlist learning. So your configuration file should include these lines: @example [hostlist] OPTIONS = -b -e HTTPPORT = 8080 SERVERS = http://v10.gnunet.org/hostlist [^] HOSTLISTFILE = $SERVICEHOME/hostlists.file @end example @node Configuration of the HOSTLIST proxy settings @subsection 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 @command{gnunet-setup} tool. The hostlist client supports the following proxy types at the moment: @itemize @bullet @item HTTP and HTTP 1.0 only proxy @item SOCKS 4/4a/5/5 with hostname @end itemize In addition authentication at the proxy with username and password can be configured. To configure proxy support for the hostlist client in the @command{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 @code{[hostlist]} section of the configuration: @example # 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 = @end example @node Configuring your peer to provide a hostlist @subsection 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 @command{-p} option to @code{OPTIONS} in the @code{[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: @example [hostlist] HTTPPORT = 12980 OPTIONS = -p @end example @noindent 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: @example [hostlist] EXTERNAL_DNS_NAME = example.org HTTPPORT = 12981 OPTIONS = -p -a @end example @noindent 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 @code{@uref{http://example.org:12981/, http://example.org:12981/}}. Please notice: @itemize @bullet @item The hostlist is @b{not} human readable, so you should not try to download it using your webbrowser. Just point your GNUnet peer to the address! @item Advertising without providing a hostlist does not make sense and will not work. @end itemize @node Configuring the datastore @subsection 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 @code{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. @node Configuring the MySQL database @subsection 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. @node Reasons for using MySQL @subsection Reasons for using MySQL @itemize @bullet @item On up-to-date hardware where mysql can be used comfortably, this module will have better performance than the other database choices (according to our tests). @item Its often possible to recover the mysql database from internal inconsistencies. Some of the other databases do not support repair. @end itemize @node Reasons for not using MySQL @subsection Reasons for not using MySQL @itemize @bullet @item Memory usage (likely not an issue if you have more than 1 GB) @item Complex manual setup @end itemize @node Setup Instructions @subsection Setup Instructions @itemize @bullet @item In @file{gnunet.conf} set in section @code{DATASTORE} the value for @code{DATABASE} to @code{mysql}. @item Access mysql as root: @example $ mysql -u root -p @end example @noindent and issue the following commands, replacing $USER with the username that will be running @command{gnunet-arm} (so typically "gnunet"): @example 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; @end example @item In the $HOME directory of $USER, create a @file{.my.cnf} file with the following lines @example [client] user=$USER password=$the_password_you_like @end example @end itemize That's it. Note that @file{.my.cnf} file is a slight security risk unless its on a safe partition. The @file{$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. @node Testing @subsection Testing You should briefly try if the database connection works. First, login as $USER. Then use: @example $ mysql -u $USER mysql> use gnunet; @end example @noindent If you get the message @example Database changed @end example @noindent it probably works. If you get @example ERROR 2002: Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2) @end example @noindent it may be resolvable by @example ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock @end example @noindent so there may be some additional trouble depending on your mysql setup. @node Performance Tuning @subsection Performance Tuning For GNUnet, you probably want to set the option @example innodb_flush_log_at_trx_commit = 0 @end example @noindent 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. @node Setup for running Testcases @subsection 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 (@command{make check}). @node Configuring the Postgres database @subsection 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. @node Reasons to use Postgres @subsection Reasons to use Postgres @itemize @bullet @item Easier to setup than MySQL @item Real database @end itemize @node Reasons not to use Postgres @subsection Reasons not to use Postgres @itemize @bullet @item Quite slow @item Still some manual setup required @end itemize @node Manual setup instructions @subsection Manual setup instructions @itemize @bullet @item In @file{gnunet.conf} set in section @code{DATASTORE} the value for @code{DATABASE} to @code{postgres}. @item Access Postgres to create a user: @table @asis @item with Postgres 8.x, use: @example # su - postgres $ createuser @end example @noindent 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. @item with Postgres 9.x, use: @example # su - postgres $ createuser -d $GNUNET_USER @end example @noindent where $GNUNET_USER is the name of the user running GNUnet. @end table @item As that user (so typically as user "gnunet"), create a database (or two): @example $ createdb gnunet # this way you can run "make check" $ createdb gnunetcheck @end example @end itemize Now you should be able to start @code{gnunet-arm}. @node Testing the setup manually @subsection Testing the setup manually You may want to try if the database connection works. First, again login as the user who will run @command{gnunet-arm}. Then use: @example $ psql gnunet # or gnunetcheck gnunet=> \dt @end example @noindent If, after you have started @command{gnunet-arm} at least once, you get a @code{gn090} table here, it probably works. @node Configuring the datacache @subsection 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 @code{QUOTA} option in the section @code{[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. @node Configuring the file-sharing service @subsection 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 @code{START_ON_DEMAND} option in section @code{[fs]} to "YES". Alternatively, you can run @example $ gnunet-arm -i fs @end example @noindent 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). @node Configuring logging @subsection Configuring logging Since version 0.9.0, logging in GNUnet is controlled via the @code{-L} and @code{-l} options. Using @code{-L}, a log level can be specified. With log level @code{ERROR} only serious errors are logged. The default log level is @code{WARNING} which causes anything of concern to be logged. Log level @code{INFO} can be used to log anything that might be interesting information whereas @code{DEBUG} can be used by developers to log debugging messages (but you need to run @code{./configure} with @code{--enable-logging=verbose} to get them compiled). The @code{-l} option is used to specify the log file. Since most GNUnet services are managed by @code{gnunet-arm}, using the @code{-l} or @code{-L} options directly is not possible. Instead, they can be specified using the @code{OPTIONS} configuration value in the respective section for the respective service. In order to enable logging globally without editing the @code{OPTIONS} values for each service, @command{gnunet-arm} supports a @code{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 @code{OPTIONS} field. @code{GLOBAL_POSTFIX} can contain the special sequence "@{@}" which is replaced by the name of the service that is being started. Furthermore, @code{GLOBAL_POSTFIX} is special in that sequences starting with "$" anywhere in the string are expanded (according to options in @code{PATHS}); this expansion otherwise is only happening for filenames and then the "$" must be the first character in the option. Both of these restrictions do not apply to @code{GLOBAL_POSTFIX}. Note that specifying @code{%} anywhere in the @code{GLOBAL_POSTFIX} disables both of these features. In summary, in order to get all services to log at level @code{INFO} to log-files called @code{SERVICENAME-logs}, the following global prefix should be used: @example GLOBAL_POSTFIX = -l $SERVICEHOME/@{@}-logs -L INFO @end example @node Configuring the transport service and plugins @subsection 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 @example 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 @end example Different are the settings for the plugins to load @code{PLUGINS}. The first setting specifies which transport plugins to load. @itemize @bullet @item 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 @example [transport-unix] PORT = 22086 TESTING_IGNORE_KEYS = ACCEPT_FROM; @end example @item transport-tcp A plugin for communication with TCP. Set port to 0 for client mode with outbound only connections @example [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 @end example @item transport-udp A plugin for communication with UDP. Supports peer discovery using broadcasts. @example [transport-udp] PORT = 2086 BROADCAST = YES BROADCAST_INTERVAL = 30 s MAX_BPS = 1000000 TESTING_IGNORE_KEYS = ACCEPT_FROM; @end example @item 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. @example [transport-http_client] MAX_CONNECTIONS = 128 TESTING_IGNORE_KEYS = ACCEPT_FROM; @end example @example [transport-https_client] MAX_CONNECTIONS = 128 TESTING_IGNORE_KEYS = ACCEPT_FROM; @end example @noindent 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 @code{EXTERNAL_HOSTNAME} setting. The webserver under this address should forward the request to the peer and the configure port. @example [transport-http_server] EXTERNAL_HOSTNAME = fulcrum.net.in.tum.de/gnunet PORT = 1080 MAX_CONNECTIONS = 128 TESTING_IGNORE_KEYS = ACCEPT_FROM; @end example @example [transport-https_server] PORT = 4433 CRYPTO_INIT = NORMAL KEY_FILE = https.key CERT_FILE = https.cert MAX_CONNECTIONS = 128 TESTING_IGNORE_KEYS = ACCEPT_FROM; @end example @item transport-wlan The next section describes how to setup the WLAN plugin, so here only the settings. Just specify the interface to use: @example [transport-wlan] # Name of the interface in monitor mode (typically monX) INTERFACE = mon0 # Real hardware, no testing TESTMODE = 0 TESTING_IGNORE_KEYS = ACCEPT_FROM; @end example @end itemize @node Configuring the WLAN transport plugin @subsection 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. @menu * Requirements for the WLAN plugin:: * Configuration:: * Before starting GNUnet:: * Limitations and known bugs:: @end menu @node Requirements for the WLAN plugin @subsubsection Requirements for the WLAN plugin @itemize @bullet @item wlan network card with monitor support and packet injection (see @uref{http://www.aircrack-ng.org/, aircrack-ng.org}) @item Linux kernel with mac80211 stack, introduced in 2.6.22, tested with 2.6.35 and 2.6.38 @item Wlantools to create the a monitor interface, tested with airmon-ng of the aircrack-ng package @end itemize @node Configuration @subsubsection 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) @example # 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 @end example @node Before starting GNUnet @subsubsection 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: @example sudo airmon-ng start wlan0 @end example @noindent Here is an example what the result should look like: @example Interface Chipset Driver wlan0 Intel 4965 a/b/g/n iwl4965 - [phy0] (monitor mode enabled on mon0) @end example @noindent The monitor interface is mon0 is the one that you have to put into the configuration file. @node Limitations and known bugs @subsubsection 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, e.g. by using: @example iwconfig wlan0 channel 1 @end example @node Configuring HTTP(S) reverse proxy functionality using Apache or nginx @subsection 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 website this improves censorship resistance since it looks as normal surfing behaviour. To do so, you have to do two things: @itemize @bullet @item Configure your webserver to forward the GNUnet HTTP traffic @item Configure your GNUnet peer to announce the respective address @end itemize As an example we want to use GNUnet peer running: @itemize @bullet @item HTTP server plugin on @code{gnunet.foo.org:1080} @item HTTPS server plugin on @code{gnunet.foo.org:4433} @item A apache or nginx webserver on @uref{http://www.foo.org/, http://www.foo.org:80/} @item A apache or nginx webserver on https://www.foo.org:443/ @end itemize And we want the webserver to accept GNUnet traffic under @code{http://www.foo.org/bar/}. The required steps are described here: @menu * Reverse Proxy - Configure your Apache2 HTTP webserver:: * Reverse Proxy - Configure your Apache2 HTTPS webserver:: * Reverse Proxy - Configure your nginx HTTPS webserver:: * Reverse Proxy - Configure your nginx HTTP webserver:: * Reverse Proxy - Configure your GNUnet peer:: @end menu @node Reverse Proxy - Configure your Apache2 HTTP webserver @subsubsection Reverse Proxy - Configure your Apache2 HTTP webserver First of all you need mod_proxy installed. Edit your webserver configuration. Edit @code{/etc/apache2/apache2.conf} or the site-specific configuration file. In the respective @code{server config},@code{virtual host} or @code{directory} section add the following lines: @example ProxyTimeout 300 ProxyRequests Off ProxyPass http://gnunet.foo.org:1080/ ProxyPassReverse http://gnunet.foo.org:1080/ @end example @node Reverse Proxy - Configure your Apache2 HTTPS webserver @subsubsection 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 @file{apache2/sites-available/default-ssl}. In the respective HTTPS @code{server config},@code{virtual host} or @code{directory} section add the following lines: @example SSLProxyEngine On ProxyTimeout 300 ProxyRequests Off ProxyPass https://gnunet.foo.org:4433/ ProxyPassReverse https://gnunet.foo.org:4433/ @end example @noindent More information about the apache mod_proxy configuration can be found in the @uref{http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass, Apache documentation}. @node Reverse Proxy - Configure your nginx HTTPS webserver @subsubsection Reverse Proxy - Configure your nginx HTTPS webserver Since nginx does not support chunked encoding, you first of all have to install the @code{chunkin} @uref{http://wiki.nginx.org/HttpChunkinModule, module}. To enable chunkin add: @example chunkin on; error_page 411 = @@my_411_error; location @@my_411_error @{ chunkin_resume; @} @end example @noindent Edit your webserver configuration. Edit @file{/etc/nginx/nginx.conf} or the site-specific configuration file. In the @code{server} section add: @example 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; @} @end example @node Reverse Proxy - Configure your nginx HTTP webserver @subsubsection Reverse Proxy - Configure your nginx HTTP webserver Edit your webserver configuration. Edit @file{/etc/nginx/nginx.conf} or the site-specific configuration file. In the @code{server} section add: @example 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; @} @end example @node Reverse Proxy - Configure your GNUnet peer @subsubsection Reverse Proxy - Configure your GNUnet peer To have your GNUnet peer announce the address, you have to specify the @code{EXTERNAL_HOSTNAME} option in the @code{[transport-http_server]} section: @example [transport-http_server] EXTERNAL_HOSTNAME = http://www.foo.org/bar/ @end example @noindent and/or @code{[transport-https_server]} section: @example [transport-https_server] EXTERNAL_HOSTNAME = https://www.foo.org/bar/ @end example @noindent Now restart your webserver and your peer... @node Blacklisting peers @subsection Blacklisting peers Transport service supports to deny connecting to a specific peer of to a specific peer with a specific transport plugin using the 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: @c FIXME: This is too long and produces errors in the pdf. @example [transport-blacklist AG2PHES1BARB9IJCPAMJTFPVJ5V3A72S3F2A8SBUB8DAQ2V0O3V8G6G2JU56FHGFOHMQVKBSQFV98TCGTC3RJ1NINP82G0RC00N1520] P565723JO1C2HSN6J29TAQ22MN6CI8HTMUU55T0FUQG4CMDGGEQ8UCNBKUMB94GC8R9G4FB2SF9LDOBAJ6AMINBP4JHHDD6L7VD801G = tcp @end example To blacklist connections to P565... on peer AG2P... using all plugins add: @example [transport-blacklist-AG2PHES1BARB9IJCPAMJTFPVJ5V3A72S3F2A8SBUB8DAQ2V0O3V8G6G2JU56FHGFOHMQVKBSQFV98TCGTC3RJ1NINP82G0RC00N1520] P565723JO1C2HSN6J29TAQ22MN6CI8HTMUU55T0FUQG4CMDGGEQ8UCNBKUMB94GC8R9G4FB2SF9LDOBAJ6AMINBP4JHHDD6L7VD801G = @end example You can also add a blacklist client using 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) @itemize @bullet @item Do we have a local blacklist entry for this peer and this plugin? @item YES: disallow connection @item Do we have a local blacklist entry for this peer and all plugins? @item YES: disallow connection @item Does one of the clients disallow? @item YES: disallow connection @end itemize @node Configuration of the HTTP and HTTPS transport plugins @subsection 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: @itemize @bullet @item HTTP 1.1 proxy @item SOCKS 4/4a/5/5 with hostname @end itemize 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 @code{[transport-http_client]} and @code{[transport-https_client]} section of the configuration: @example # 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 = @end example @node Configuring the GNU Name System @subsection Configuring the GNU Name System @menu * Configuring system-wide DNS interception:: * Configuring the GNS nsswitch plugin:: @c * Configuring GNS on W32:: * GNS Proxy Setup:: * Setup of the GNS CA:: * Testing the GNS setup:: * Migrating existing DNS zones into GNS:: @end menu @node Configuring system-wide DNS interception @subsubsection 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 @code{gnunet-service-arm} as user and group 'gnunet'. You also need to be sure to run @code{make install} as root (or use the @code{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 @code{gnunet-service-dns} will then start helper programs that will make the necessary changes to your firewall (@code{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: @itemize @bullet @item 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 @code{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 @code{gnunet-gns-proxy} and inform your browser to use the Socks5 proxy which @code{gnunet-gns-proxy} makes available by default on port 7777. @item 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. @item Use a W32 resolver plugin (recommended on W32)@* This is currently the only option on W32 systems. @item 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). @end itemize 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. @node Configuring the GNS nsswitch plugin @subsubsection 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 @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 @itemize @bullet @item install GNUnet as root or @item compile GNUnet with the @code{--with-sudo=yes} switch. @end itemize Name resolution is controlled by the @emph{hosts} section in the NSS configuration. By default this section first performs a lookup in the @file{/etc/hosts} file and then in DNS. The nsswitch file should contain a line similar to: @example hosts: files dns [NOTFOUND=return] mdns4_minimal mdns4 @end example @noindent 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 @file{/etc/nsswitch.conf} file before DNS related plugins: @example ... hosts: files gns [NOTFOUND=return] dns mdns4_minimal mdns4 ... @end example @noindent The @code{NOTFOUND=return} will ensure that if a @code{.gnu} name is not found in GNS it will not be queried in DNS. @c @node Configuring GNS on W32 @c @subsubsection Configuring GNS on W32 @c This document is a guide to configuring GNU Name System on W32-compatible @c platforms. @c After GNUnet is installed, run the w32nsp-install tool: @c @example @c w32nsp-install.exe libw32nsp-0.dll @c @end example @c @noindent @c ('0' is the library version of W32 NSP; it might increase in the future, @c change the invocation accordingly). @c This will install GNS namespace provider into the system and allow other @c applications to resolve names that end in '@strong{gnu}' @c and '@strong{zkey}'. Note that namespace provider requires @c gnunet-gns-helper-service-w32 to be running, as well as gns service @c itself (and its usual dependencies). @c Namespace provider is hardcoded to connect to @strong{127.0.0.1:5353}, @c and this is where gnunet-gns-helper-service-w32 should be listening to @c (and is configured to listen to by default). @c To uninstall the provider, run: @c @example @c w32nsp-uninstall.exe @c @end example @c @noindent @c (uses provider GUID to uninstall it, does not need a dll name). @c Note that while MSDN claims that other applications will only be able to @c use the new namespace provider after re-starting, in reality they might @c stat to use it without that. Conversely, they might stop using the @c provider after it's been uninstalled, even if they were not re-started. @c W32 will not permit namespace provider library to be deleted or @c overwritten while the provider is installed, and while there is at least @c one process still using it (even after it was uninstalled). @node GNS Proxy Setup @subsubsection 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: @itemize @bullet @item 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 @code{Host: example.com} header in the request from your browser. However, your browser might be using @code{example.gnu} for the @code{Host} header and might only accept (and send) cookies for @code{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). @item 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 @code{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. @item 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) @end itemize @node Setup of the GNS CA @subsubsection 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: @example $ gnunet-gns-proxy-setup-ca @end example @noindent 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 @code{*.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 @b{not} work with libcurl compiled against OpenSSL. You can check the configuration your libcurl was build with by running: @example curl --version @end example the output will look like this (without the linebreaks): @example 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 @end example @node Testing the GNS setup @subsubsection Testing the GNS setup Now for testing purposes we can create some records in our zone to test the SSL functionality of the proxy: @example $ 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 @end example @noindent At this point we can start the proxy. Simply execute @example $ gnunet-arm -i gns-proxy @end example To run the proxy at all times in the future, you should change your configuration as follows: @example $ gnunet-config -s gns-proxy -o AUTOSTART -V YES @end example @noindent Configure your browser to use this SOCKSv5 proxy using @code{localhost} on port 7777. If you use @command{Firefox} (or one of its derivatives/forks such as Icecat) you also have to go to @code{about:config} and set the key @code{network.proxy.socks_remote_dns} to @code{true}. When you visit @code{https://homepage.test/}, you should get to the @code{https://gnunet.org/} frontpage and the browser (with the correctly configured proxy) should give you a valid SSL certificate for @code{homepage.gnu} and no warnings. It should look like this: @c FIXME: Image does not exist, create it or save it from Drupal? @c @image{images/gnunethpgns.png,5in,, picture of homepage.gnu in Webbrowser} @node Migrating existing DNS zones into GNS @subsubsection 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: @code{https://git.gnunet.org/ascension.git/} The software can be installed into a Python virtual environment like this: @example $ python3 -m venv .venv $ source .venv/bin/activate $ python3 setup.py install @end example Or installed globally like this: @example $ sudo python3 setup.py install @end example 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 systems Python installation and its dependencies. Another way to install Ascension on Debian is to install the python3-ascension package. It can be found within the above mentioned Ascension git repository. This also adds a system user called ascension and runs a GNUnet peer in the background. Please note: This only works if a recent version of GNUnet is installed on your system. The version number of Ascension is chosen according to the required feature level of GNUnet: Ascension 0.11.5 is only compatible with GNUnet 0.11.5 or later and so on. As Debian's packages for GNUnet are outdated even in experimental, you will need to install GNUnet manually @xref{Installing GNUnet}. Please check @xref{Migrating an existing DNS zone into GNS}, for usage manual of the tool. @node Configuring the GNUnet VPN @subsection Configuring the GNUnet VPN @menu * IPv4 address for interface:: * IPv6 address for interface:: * Configuring the GNUnet VPN DNS:: * Configuring the GNUnet VPN Exit Service:: * IP Address of external DNS resolver:: * IPv4 address for Exit interface:: * IPv6 address for Exit interface:: @end menu 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. @pxref{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: @node IPv4 address for interface @subsubsection IPv4 address for interface This is the IPv4 address the VPN interface will get. You should pick a 'private' IPv4 network that is not yet in use for you system. For example, if you use @code{10.0.0.1/255.255.0.0} already, you might use @code{10.1.0.1/255.255.0.0}. If you use @code{10.0.0.1/255.0.0.0} already, then you might use @code{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 (@code{255.255.0.0} or, even better, @code{255.0.0.0}) to allow more mappings of remote IP Addresses into this range. However, even a @code{255.255.255.0} mask will suffice for most users. @node IPv6 address for interface @subsubsection 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 @code{fe80:}). A subnet Unique Local Unicast (@code{fd00::/8} prefix) that you are currently not using would be a good choice. @node Configuring the GNUnet VPN DNS @subsubsection Configuring the GNUnet VPN DNS To resolve names for remote nodes, activate the DNS exit option. @node Configuring the GNUnet VPN Exit Service @subsubsection 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 do other mischiefs 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 (e.g. 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: @node IP Address of external DNS resolver @subsubsection 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. @node IPv4 address for Exit interface @subsubsection 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. @node IPv6 address for Exit interface @subsubsection 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 @code{2001:4ca0::1234/64}, then using @code{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 (@code{2001:4ca0::1:0/112} for example) through your computer (this should be automatic with IPv6, but obviously anything can be disabled). @node Bandwidth Configuration @subsection 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. @node Configuring NAT @subsection 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. @node Peer configuration for distributors (e.g. Operating Systems) @subsection Peer configuration for distributors (e.g. Operating Systems) The "GNUNET_DATA_HOME" in "[PATHS]" in @file{/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, distributors may consider pointing "GNUNET_RUNTIME_DIR" to "/var/run/gnunet/" and "GNUNET_HOME" to "/var/lib/gnunet/". Also, should a distributor decide to override system defaults, all of these changes should be done in a custom @file{/etc/gnunet.conf} and not in the files in the @file{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". Distributors might want to include a wrapper for gnunet-setup that allows the desktop-user to "sudo" (e.g. using gtksudo) to the "gnunet" user account and then runs "gnunet-arm -e", "gnunet-setup" and "gnunet-arm -s" in sequence. @node Config Leftovers @section 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 @file{$GNUNET_PREFIX/share/gnunet/config.d/} directory, so in practice you could simply start without any configuration. If you want to configure your peer later, you need to stop it before invoking the @code{gnunet-setup} tool to customize further and to test your configuration (@code{gnunet-setup} has built-in test functions). The most important option you might have to still set by hand is in [PATHS]. Here, you use the option "GNUNET_HOME" to specify the path where GNUnet should store its data. It defaults to @code{$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. @menu * The Single-User Setup:: * The Multi-User Setup:: * Killing GNUnet services:: * Access Control for GNUnet:: @end menu @node The Single-User Setup @subsection 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 @code{gnunet-arm}. By default, GNUnet looks in @file{~/.config/gnunet.conf} for a configuration (or @code{$XDG_CONFIG_HOME/gnunet.conf} if@ @code{$XDG_CONFIG_HOME} is defined). If your configuration lives elsewhere, you need to pass the @code{-c FILENAME} option to all GNUnet commands. Assuming the configuration file is called @file{~/.config/gnunet.conf}, you start your peer using the @code{gnunet-arm} command (say as user @code{gnunet}) using: @example gnunet-arm -c ~/.config/gnunet.conf -s @end example @noindent The "-s" option here is for "start". The command should return almost instantly. If you want to stop GNUnet, you can use: @example gnunet-arm -c ~/.config/gnunet.conf -e @end example @noindent 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): @example gnunet-arm -c ~/.config/gnunet.conf -i fs @end example @noindent The "-i fs" option here is for "initialize" the "fs" (file-sharing) application. You can also selectively kill only file-sharing support using @example gnunet-arm -c ~/.config/gnunet.conf -k fs @end example @noindent 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: @example gnunet-arm -c ~/.config/gnunet.conf -s @end example @noindent Alternatively, you can combine the two options: @example gnunet-arm -c ~/.config/gnunet.conf -s -i fs @end example @noindent Using @code{gnunet-arm} is also the preferred method for initializing GNUnet from @code{init}. Finally, you should edit your @code{crontab} (using the @code{crontab} command) and insert a line@ @example @@reboot gnunet-arm -c ~/.config/gnunet.conf -s @end example to automatically start your peer whenever your system boots. @node The Multi-User Setup @subsection The Multi-User Setup This requires you to create a user @code{gnunet} and an additional group @code{gnunetdns}, prior to running @code{make install} during installation. Then, you create a configuration file @file{/etc/gnunet.conf} which should contain the lines:@ @example [arm] START_SYSTEM_SERVICES = YES START_USER_SERVICES = NO @end example @noindent Then, perform the same steps to run GNUnet as in the per-user configuration, except as user @code{gnunet} (including the @code{crontab} installation). You may also want to run @code{gnunet-setup} to configure your peer (databases, etc.). Make sure to pass @code{-c /etc/gnunet.conf} to all commands. If you run @code{gnunet-setup} as user @code{gnunet}, you might need to change permissions on @file{/etc/gnunet.conf} so that the @code{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 (@code{$USER}) permission to the group gnunet: @example # adduser $USER gnunet @end example @noindent Then, create a configuration file in @file{~/.config/gnunet.conf} for the $USER with the lines: @example [arm] START_SYSTEM_SERVICES = NO START_USER_SERVICES = YES @end example @noindent This will ensure that @code{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 @file{/etc/gnunet.conf} and ignore options set by individual users. Again, each user should then start the peer using @file{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) @code{gnunet-service-arm} processes running in your system. @node Killing GNUnet services @subsection 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 @code{gnunet-service} processes is generally not a successful method for stopping a peer (since @code{gnunet-service-arm} will instantly restart them). The best way to explicitly stop a peer is using @code{gnunet-arm -e}; note that the per-user services may need to be terminated before the system-wide services will terminate normally. @node Access Control for GNUnet @subsection 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: @table @asis @item 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. @item 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. @item 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. @item 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. @end table @c FIXME: The titles of these chapters are too long in the index. @menu * Recommendation - Disable access to services via TCP:: * Recommendation - Run most services as system user "gnunet":: * Recommendation - Control access to services using group "gnunet":: * Recommendation - Limit access to certain SUID binaries by group "gnunet":: * Recommendation - Limit access to critical gnunet-helper-dns to group "gnunetdns":: * Differences between "make install" and these recommendations:: @end menu @node Recommendation - Disable access to services via TCP @subsubsection 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. Since 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. @node Recommendation - Run most services as system user "gnunet" @subsubsection 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 @file{/var/lib/gnunet} and the configuration file should be @file{/etc/gnunet.conf}. Only the @code{gnunet} user should have the right to access @file{/var/lib/gnunet} (@emph{mode: 700}). @node Recommendation - Control access to services using group "gnunet" @subsubsection 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). @node Recommendation - Limit access to certain SUID binaries by group "gnunet" @subsubsection 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). @node Recommendation - Limit access to critical gnunet-helper-dns to group "gnunetdns" @subsubsection 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). @b{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, @strong{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". @node Differences between "make install" and these recommendations @subsubsection 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 @code{--with-gnunetdns=GRPNAME} configure option.