@itemize @bullet
@item developed by a community that believes in the GNU philosophy
@item Free Software (Free as in Freedom), licensed under the
-GNU General Public License@footnote{@uref{https://www.gnu.org/licenses/licenses.html#GPL, https://www.gnu.org/licenses/licenses.html#GPL}}
+GNU Affero General Public License@footnote{@uref{https://www.gnu.org/licenses/licenses.html#AGPL, https://www.gnu.org/licenses/licenses.html#AGPL}}
@item A set of standards, including coding conventions and
architectural rules
@item A set of layered protocols, both specifying the communication
@menu
* Developer Introduction::
+* Internal Dependencies::
* Code overview::
* System Architecture::
* Subsystem stability::
* Build-system::
* Developing extensions for GNUnet using the gnunet-ext template::
* Writing testcases::
+* Building GNUnet and its dependencies::
* TESTING library::
* Performance regression analysis with Gauger::
* TESTBED Subsystem::
those that have a public website) which build on top of the GNUnet
framework.
+@c ***********************************************************************
+@node Internal dependencies
+@section Internal dependencies
+
+This section tries to give an overview of what processes a typical GNUnet
+peer running a particular application would consist of. All of the
+processes listed here should be automatically started by
+@command{gnunet-arm -s}.
+The list is given as a rough first guide to users for failure diagnostics.
+Ideally, end-users should never have to worry about these internal
+dependencies.
+
+In terms of internal dependencies, a minimum file-sharing system consists
+of the following GNUnet processes (in order of dependency):
+
+@itemize @bullet
+@item gnunet-service-arm
+@item gnunet-service-resolver (required by all)
+@item gnunet-service-statistics (required by all)
+@item gnunet-service-peerinfo
+@item gnunet-service-transport (requires peerinfo)
+@item gnunet-service-core (requires transport)
+@item gnunet-daemon-hostlist (requires core)
+@item gnunet-daemon-topology (requires hostlist, peerinfo)
+@item gnunet-service-datastore
+@item gnunet-service-dht (requires core)
+@item gnunet-service-identity
+@item gnunet-service-fs (requires identity, mesh, dht, datastore, core)
+@end itemize
+
+@noindent
+A minimum VPN system consists of the following GNUnet processes (in
+order of dependency):
+
+@itemize @bullet
+@item gnunet-service-arm
+@item gnunet-service-resolver (required by all)
+@item gnunet-service-statistics (required by all)
+@item gnunet-service-peerinfo
+@item gnunet-service-transport (requires peerinfo)
+@item gnunet-service-core (requires transport)
+@item gnunet-daemon-hostlist (requires core)
+@item gnunet-service-dht (requires core)
+@item gnunet-service-mesh (requires dht, core)
+@item gnunet-service-dns (requires dht)
+@item gnunet-service-regex (requires dht)
+@item gnunet-service-vpn (requires regex, dns, mesh, dht)
+@end itemize
+
+@noindent
+A minimum GNS system consists of the following GNUnet processes (in
+order of dependency):
+
+@itemize @bullet
+@item gnunet-service-arm
+@item gnunet-service-resolver (required by all)
+@item gnunet-service-statistics (required by all)
+@item gnunet-service-peerinfo
+@item gnunet-service-transport (requires peerinfo)
+@item gnunet-service-core (requires transport)
+@item gnunet-daemon-hostlist (requires core)
+@item gnunet-service-dht (requires core)
+@item gnunet-service-mesh (requires dht, core)
+@item gnunet-service-dns (requires dht)
+@item gnunet-service-regex (requires dht)
+@item gnunet-service-vpn (requires regex, dns, mesh, dht)
+@item gnunet-service-identity
+@item gnunet-service-namestore (requires identity)
+@item gnunet-service-gns (requires vpn, dns, dht, namestore, identity)
+@end itemize
+
@c ***********************************************************************
@node Code overview
@section Code overview
testcases. Thus the canonical command @code{make check install} has to be
changed to @code{make install check} for GNUnet.
+@c ***********************************************************************
+@cindex Building GNUnet
+@node Building GNUnet and its dependencies
+@section Building GNUnet and its dependencies
+
+In the following section we will outline how to build GNUnet and
+some of its dependencies. We will assume a fair amount of knowledge
+for building applications under UNIX-like systems. Furthermore we
+assume that the build environment is sane and that you are aware of
+any implications actions in this process could have.
+Instructions here can be seen as notes for developers (an extension to
+the 'HACKING' section in README) as well as package mantainers.
+@b{Users should rely on the available binary packages.}
+We will use Debian as an example Operating System environment. Substitute
+accordingly with your own Ooperating System environment.
+
+For the full list of depenendencies, consult the appropriate, up-to-date
+section in the @file{README} file.
+
+First, we need to build or install (depending on your OS) the following
+packages. If you build them from source, build them in this exact order:
+
+@exmaple
+libgpgerror, libgcrypt, libnettle, libunbound, GnuTLS (with libunbound
+support)
+@end example
+
+After we have build and installed those packages, we continue with
+packages closer to GNUnet in this step: libgnurl (our libcurl fork),
+GNU libmicrohttpd, and GNU libextractor. Again, if your package manager
+provides one of these packages, use the packages provided from it
+unless you have good reasons (package version too old, conflicts, etc).
+We advise against compiling widely used packages such as GnuTLS
+yourself if your OS provides a variant already unless you take care
+of maintenance of the packages then.
+
+In the optimistic case, this command will give you all the dependencies:
+
+@example
+sudo apt-get install libgnurl libmicrohttpd libextractor
+@end example
+
+From experience we know that at the very least libgnurl is not
+available in some environments. You could substitute libgnurl
+with libcurl, but we recommend to install libgnurl, as it gives
+you a predefined libcurl with the small set GNUnet requires. In
+the past namespaces of libcurl and libgnurl were shared, which
+caused problems when you wanted to integrate both of them in one
+Operating System. This has been resolved, and they can be installed
+side by side now.
+
+@cindex libgnurl
+@cindex compiling libgnurl
+GNUnet and some of its function depend on a limited subset of cURL/libcurl.
+Rather than trying to enforce a certain configuration on the world, we
+opted to maintain a microfork of it that ensures we can link against the
+right set of features. We called this specialized set of libcurl
+``libgnurl''. It is fully ABI compatible with libcurl and currently used
+by GNUnet and some of its dependencies.
+
+We download libgnurl and its digital signature from the GNU fileserver,
+assuming @env{TMPDIR} exists@footnote{It might be @file{/tmp}, @env{TMPDIR}, @env{TMP} or any other location. For consistency we assume @env{TMPDIR} points to @file{/tmp} for the remainder of this section.}
+
+@example
+cd \$TMPDIR
+wget https://ftp.gnu.org/gnu/gnunet/gnurl-7.60.0.tar.Z
+wget https://ftp.gnu.org/gnu/gnunet/gnurl-7.60.0.tar.Z.sig
+@end example
+
+Next, verify the digital signature of the file:
+
+@example
+gpg --verify gnurl-7.60.0.tar.Z.sig
+@end example
+
+If gpg fails, you might try with @command{gpg2} on your OS. If the error
+states that ``the key can not be found'' or it is unknown, you have to
+retrieve the key (A88C8ADD129828D7EAC02E52E22F9BBFEE348588) from a
+keyserver first:
+
+@example
+gpg --keyserver pgp.mit.edu --recv-keys A88C8ADD129828D7EAC02E52E22F9BBFEE348588
+@end example
+
+and rerun the verification command.
+
+libgnurl will require the following packages to be present at runtime:
+gnutls (with DANE support / libunbound), libidn, zlib and at compile time:
+libtool, groff, perl, pkg-config, and python 2.7.
+
+Once you have verified that all the required packages are present on your
+system, we can proceed to compile libgnurl:
+
+@example
+tar -xvf gnurl-7.60.0.tar.Z
+cd gnurl-7.60.0
+sh configure --disable-ntlm-wb
+make
+make -C tests test
+sudo make install
+@end example
+
+After you've compiled and installed libgnurl, we can proceed to building
+GNUnet.
+
+
+
+
+First, in addition to the GNUnet sources you might require downloading the
+latest version of various dependencies, depending on how recent the
+software versions in your distribution of GNU/Linux are.
+Most distributions do not include sufficiently recent versions of these
+dependencies.
+Thus, a typically installation on a "modern" GNU/Linux distribution
+requires you to install the following dependencies (ideally in this
+order):
+
+@itemize @bullet
+@item libgpgerror and libgcrypt
+@item libnettle and libunbound (possibly from distribution), GnuTLS
+@item libgnurl (read the README)
+@item GNU libmicrohttpd
+@item GNU libextractor
+@end itemize
+
+Make sure to first install the various mandatory and optional
+dependencies including development headers from your distribution.
+
+Other dependencies that you should strongly consider to install is a
+database (MySQL, sqlite or Postgres).
+The following instructions will assume that you installed at least sqlite.
+For most distributions you should be able to find pre-build packages for
+the database. Again, make sure to install the client libraries @b{and} the
+respective development headers (if they are packaged separately) as well.
+
+You can find specific, detailed instructions for installing of the
+dependencies (and possibly the rest of the GNUnet installation) in the
+platform-specific descriptions, which can be found in the Index.
+Please consult them now.
+If your distribution is not listed, please study
+@ref{Build instructions for Debian 8}, the build instructions for
+Debian stable, carefully as you try to install the dependencies for your
+own distribution.
+Contributing additional instructions for further platforms is always
+appreciated.
+Please take in mind that operating system development tends to move at
+a rather fast speed. Due to this you should be aware that some of
+the instructions could be outdated by the time you are reading this.
+If you find a mistake, please tell us about it (or even better: send
+a patch to the documentation to fix it!).
+
+Before proceeding further, please double-check the dependency list.
+Note that in addition to satisfying the dependencies, you might have to
+make sure that development headers for the various libraries are also
+installed.
+There maybe files for other distributions, or you might be able to find
+equivalent packages for your distribution.
+
+While it is possible to build and install GNUnet without having root
+access, we will assume that you have full control over your system in
+these instructions.
+First, you should create a system user @emph{gnunet} and an additional
+group @emph{gnunetdns}. On the GNU/Linux distributions Debian and Ubuntu,
+type:
+
+@example
+sudo adduser --system --home /var/lib/gnunet --group \
+--disabled-password gnunet
+sudo addgroup --system gnunetdns
+@end example
+
+@noindent
+On other Unixes and GNU systems, this should have the same effect:
+
+@example
+sudo useradd --system --groups gnunet --home-dir /var/lib/gnunet
+sudo addgroup --system gnunetdns
+@end example
+
+Now compile and install GNUnet using:
+
+@example
+tar xvf gnunet-@value{VERSION}.tar.gz
+cd gnunet-@value{VERSION}
+./configure --with-sudo=sudo --with-nssdir=/lib
+make
+sudo make install
+@end example
+
+If you want to be able to enable DEBUG-level log messages, add
+@code{--enable-logging=verbose} to the end of the
+@command{./configure} command.
+@code{DEBUG}-level log messages are in English only and
+should only be useful for developers (or for filing
+really detailed bug reports).
+
+@noindent
+Next, edit the file @file{/etc/gnunet.conf} to contain the following:
+
+@example
+[arm]
+SYSTEM_ONLY = YES
+USER_ONLY = NO
+@end example
+
+@noindent
+You may need to update your @code{ld.so} cache to include
+files installed in @file{/usr/local/lib}:
+
+@example
+# ldconfig
+@end example
+
+@noindent
+Then, switch from user @code{root} to user @code{gnunet} to start
+the peer:
+
+@example
+# su -s /bin/sh - gnunet
+$ gnunet-arm -c /etc/gnunet.conf -s
+@end example
+
+You may also want to add the last line in the gnunet user's @file{crontab}
+prefixed with @code{@@reboot} so that it is executed whenever the system
+is booted:
+
+@example
+@@reboot /usr/local/bin/gnunet-arm -c /etc/gnunet.conf -s
+@end example
+
+@noindent
+This will only start the system-wide GNUnet services.
+Type @command{exit} to get back your root shell.
+Now, you need to configure the per-user part. For each
+user that should get access to GNUnet on the system, run
+(replace alice with your username):
+
+@example
+sudo adduser alice gnunet
+@end example
+
+@noindent
+to allow them to access the system-wide GNUnet services. Then, each
+user should create a configuration file @file{~/.config/gnunet.conf}
+with the lines:
+
+@example
+[arm]
+SYSTEM_ONLY = NO
+USER_ONLY = YES
+DEFAULTSERVICES = gns
+@end example
+
+@noindent
+and start the per-user services using
+
+@example
+$ gnunet-arm -c ~/.config/gnunet.conf -s
+@end example
+
+@noindent
+Again, adding a @code{crontab} entry to autostart the peer is advised:
+
+@example
+@@reboot /usr/local/bin/gnunet-arm -c $HOME/.config/gnunet.conf -s
+@end example
+
+@noindent
+Note that some GNUnet services (such as SOCKS5 proxies) may need a
+system-wide TCP port for each user.
+For those services, systems with more than one user may require each user
+to specify a different port number in their personal configuration file.
+
+Finally, the user should perform the basic initial setup for the GNU Name
+System (GNS) certificate authority. This is done by running:
+
+@example
+$ gnunet-gns-proxy-setup-ca
+@end example
+
+@noindent
+The first generates the default zones, wheras the second setups the GNS
+Certificate Authority with the user's browser. Now, to activate GNS in the
+normal DNS resolution process, you need to edit your
+@file{/etc/nsswitch.conf} where you should find a line like this:
+
+@example
+hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
+@end example
+
+@noindent
+The exact details may differ a bit, which is fine. Add the text
+@emph{"gns [NOTFOUND=return]"} after @emph{"files"}.
+Keep in mind that we included a backslash ("\") here just for
+markup reasons. You should write the text below on @b{one line}
+and @b{without} the "\":
+
+@example
+hosts: files gns [NOTFOUND=return] mdns4_minimal \
+[NOTFOUND=return] dns mdns4
+@end example
+
+@c FIXME: Document new behavior.
+You might want to make sure that @file{/lib/libnss_gns.so.2} exists on
+your system, it should have been created during the installation.
+
+
+@c **********************************************************************
@cindex TESTING library
@node TESTING library
@section TESTING library
* File-sharing::
* The GNU Name System::
* Using the Virtual Public Network::
+* The graphical configuration interface::
+* How to start and stop a GNUnet peer::
@end menu
@node Checking the Installation
that peer by specifying the peer's identity, service name and
protocol (--tcp or --udp) and you will again receive an IP address
that will terminate at the respective peer's service.
+
+
+
+@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 distributions::
+@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}
+application. 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
+recieve 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.
+How you build your peer with these options can be found here:
+@xref{Generic installation instructions}.
+
+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 wher
+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=$the_password_you_like
+@end example
+
+@end itemize
+
+Thats it. Note that @file{.my.cnf} file is a slight security risk unless
+its on a safe partition. The @file{$HOME/.my.cnf} can of course be
+a symbolic link.
+Luckily $USER has only priviledges 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
+@c %**end of header
+
+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{AUTOSTART} 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
+
+Logging in GNUnet 0.9.0 is controlled via the "-L" and "-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
+AUTOSTART = 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 nunber 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, i.e. 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 webiste
+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
+<Location /bar/ >
+ProxyPass http://gnunet.foo.org:1080/
+ProxyPassReverse http://gnunet.foo.org:1080/
+</Location>
+@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
+<Location /bar/ >
+ProxyPass https://gnunet.foo.org:4433/
+ProxyPassReverse https://gnunet.foo.org:4433/
+</Location>
+@end example
+
+@noindent
+More information about the apache mod_proxy configuration can be found
+in the Apache documentation@footnote{@uref{http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass, http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass}}
+
+@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} module@footnote{@uref{http://wiki.nginx.org/HttpChunkinModule, http://wiki.nginx.org/HttpChunkinModule}}
+
+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 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:
+
+@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 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)
+@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::
+* Configuring GNS on W32::
+* GNS Proxy Setup::
+* Setup of the GNS CA::
+* Testing the GNS setup::
+@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:
+
+@table @asis
+
+@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 table
+
+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
+@footnote{More accurate: NSS is a functionality of 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.
+
+@node Configuring GNS on W32
+@subsubsection 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:
+
+@example
+w32nsp-install.exe libw32nsp-0.dll
+@end example
+
+@noindent
+('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 '@strong{gnu}'
+and '@strong{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 @strong{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:
+
+@example
+w32nsp-uninstall.exe
+@end example
+
+@noindent
+(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).
+
+@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-gns-proxy
+@end example
+
+@noindent
+Configure your browser to use this SOCKSv5 proxy on port 7777 and visit
+this link.
+If you use @command{Firefox} (or one of its deriviates/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 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 an
+'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 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:
+
+@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"
+prividledges 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 distributions
+@subsection Peer configuration for distributions
+
+The "GNUNET_DATA_HOME" in "[path]" 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, 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 @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". 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.
+
+@node How to start and stop a GNUnet peer
+@section How to start and stop a GNUnet peer
+
+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{$GNUNET_PREFIX/share/gnunet/config.d/} directory, so in practice
+you could simply start without any configuration. If you want to
+configure your peer later, you need to stop it before invoking the
+@code{gnunet-setup} tool to customize further and to test your
+configuration (@code{gnunet-setup} has build-in test functions).
+
+The most important option you might have to still set by hand is in
+[PATHS]. Here, you use the option "GNUNET_HOME" to specify the path where
+GNUnet should store its data.
+It defaults to @code{$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 "FORCESTART=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]
+SYSTEM_ONLY = YES
+USER_ONLY = 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]
+SYSTEM_ONLY = NO
+USER_ONLY = 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 Priviledged 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
+priviledged 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.
+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.
+
+
+@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.
projects / oweals / gnunet.git / commitdiff