dbus-daemon man page on NetBSD

Man page or keyword search:  
man Server   9087 pages
apropos Keyword Search (all sections)
Output format
NetBSD logo
[printable version]

dbus-daemon(1)							dbus-daemon(1)

NAME
       dbus-daemon - Message bus daemon

SYNOPSIS
       dbus-daemon  dbus-daemon	 [--version] [--session] [--system] [--config-
       file=FILE]  [--print-address[=DESCRIPTOR]]   [--print-pid[=DESCRIPTOR]]
       [--fork]

DESCRIPTION
       dbus-daemon  is	the D-Bus message bus daemon. See http://www.freedesk‐
       top.org/software/dbus/ for more information about the big  picture.  D-
       Bus  is	first a library that provides one-to-one communication between
       any two applications; dbus-daemon is  an	 application  that  uses  this
       library to implement a message bus daemon. Multiple programs connect to
       the message bus daemon and can exchange messages with one another.

       There are two standard message bus instances:  the  systemwide  message
       bus  (installed	on  many systems as the "messagebus" init service) and
       the per-user-login-session message bus (started each time a  user  logs
       in).   dbus-daemon is used for both of these instances, but with a dif‐
       ferent configuration file.

       The    --session	    option     is     equivalent     to	    "--config-
       file=/usr/pkg/etc/dbus-1/session.conf"	and  the  --system  option  is
       equivalent to "--config-file=/usr/pkg/etc/dbus-1/system.conf". By  cre‐
       ating  additional  configuration	 files	and  using  the	 --config-file
       option, additional special-purpose message bus daemons  could  be  cre‐
       ated.

       The  systemwide	daemon	is  normally launched by an init script, stan‐
       dardly called simply "messagebus".

       The systemwide daemon is largely used for broadcasting  system  events,
       such as changes to the printer queue, or adding/removing devices.

       The  per-session	 daemon is used for various interprocess communication
       among desktop applications (however, it is not tied to X or the GUI  in
       any way).

       SIGHUP  will  cause the D-Bus daemon to PARTIALLY reload its configura‐
       tion file and to flush its user/group information caches. Some configu‐
       ration changes would require kicking all apps off the bus; so they will
       only take effect if you restart the daemon. Policy changes should  take
       effect with SIGHUP.

OPTIONS
       The following options are supported:

       --config-file=FILE
	      Use the given configuration file.

       --fork Force  the  message bus to fork and become a daemon, even if the
	      configuration file does not specify that	it  should.   In  most
	      contexts the configuration file already gets this right, though.

       --print-address[=DESCRIPTOR]
	      Print  the  address of the message bus to standard output, or to
	      the given file descriptor. This is used by programs that	launch
	      the message bus.

       --print-pid[=DESCRIPTOR]
	      Print  the  process ID of the message bus to standard output, or
	      to the given file descriptor. This  is  used  by	programs  that
	      launch the message bus.

       --session
	      Use  the	standard  configuration file for the per-login-session
	      message bus.

       --system
	      Use the standard configuration file for the  systemwide  message
	      bus.

       --version
	      Print the version of the daemon.

CONFIGURATION FILE
       A message bus daemon has a configuration file that specializes it for a
       particular application. For example, one configuration file  might  set
       up  the message bus to be a systemwide message bus, while another might
       set it up to be a per-user-login-session bus.

       The configuration  file	also  establishes  resource  limits,  security
       parameters, and so forth.

       The  configuration  file is not part of any interoperability specifica‐
       tion and its backward compatibility is not guaranteed; this document is
       documentation, not specification.

       The  standard systemwide and per-session message bus setups are config‐
       ured    in    the    files    "/usr/pkg/etc/dbus-1/system.conf"	   and
       "/usr/pkg/etc/dbus-1/session.conf".   These  files normally <include> a
       system-local.conf or session-local.conf; you can put local overrides in
       those files to avoid modifying the primary configuration files.

       The  configuration  file is an XML document. It must have the following
       doctype declaration:

	  <!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
	   "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">

       The following elements may be present in the configuration file.

       <busconfig>

       Root element.

       <type>

       The well-known type of the message  bus.	 Currently  known  values  are
       "system"	 and "session"; if other values are set, they should be either
       added to the D-Bus specification, or namespaced.	 The last <type>  ele‐
       ment  "wins"  (previous values are ignored). This element only controls
       which message bus specific environment variables are set	 in  activated
       clients.	  Most of the policy that distinguishes a session bus from the
       system bus is controlled from the other elements in  the	 configuration
       file.

       If  the	well-known  type  of  the  message  bus is "session", then the
       DBUS_STARTER_BUS_TYPE environment variable will be set to "session" and
       the  DBUS_SESSION_BUS_ADDRESS  environment  variable will be set to the
       address of the session bus.  Likewise, if the type of the  message  bus
       is  "system",  then the DBUS_STARTER_BUS_TYPE environment variable will
       be set to "system" and the DBUS_SESSION_BUS_ADDRESS  environment	 vari‐
       able  will  be  set to the address of the system bus (which is normally
       well known anyway).

       Example: <type>session</type>

       <include>

       Include a file <include>filename.conf</include> at this point.  If  the
       filename	 is relative, it is located relative to the configuration file
       doing the including.

       <include> has an	 optional  attribute  "ignore_missing=(yes|no)"	 which
       defaults	 to "no" if not provided. This attribute controls whether it's
       a fatal error for the included file to be absent.

       <includedir>

       Include all files  in  <includedir>foo.d</includedir>  at  this	point.
       Files  in  the  directory  are included in undefined order.  Only files
       ending in ".conf" are included.

       This is intended to allow extension of the  system  bus	by  particular
       packages.  For  example, if CUPS wants to be able to send out notifica‐
       tion  of	 printer  queue	 changes,  it  could   install	 a   file   to
       /usr/pkg/etc/dbus-1/system.d that allowed all apps to receive this mes‐
       sage and allowed the printer daemon user to send it.

       <user>

       The user account the daemon should run as, as either a  username	 or  a
       UID.  If the daemon cannot change to this UID on startup, it will exit.
       If this element is not present, the daemon  will	 not  change  or  care
       about its UID.

       The last <user> entry in the file "wins", the others are ignored.

       The  user  is  changed  after the bus has completed initialization.  So
       sockets etc. will be created before changing user, but no data will  be
       read from clients before changing user. This means that sockets and PID
       files can be created in a location that requires	 root  privileges  for
       writing.

       <fork>

       If  present, the bus daemon becomes a real daemon (forks into the back‐
       ground, etc.). This is generally used rather than  the  --fork  command
       line option.

       <keep_umask>

       If present, the bus daemon keeps its original umask when forking.  This
       may be useful to avoid affecting the behavior of child processes.

       <listen>

       Add an address that the bus should listen on. The  address  is  in  the
       standard	 D-Bus	format	that  contains	a transport name plus possible
       parameters/options.

       Example: <listen>unix:path=/tmp/foo</listen>

       Example: <listen>tcp:host=localhost,port=1234</listen>

       If there are multiple <listen> elements, then the bus listens on multi‐
       ple  addresses.	The  bus  will pass its address to started services or
       other interested parties with the last address given in <listen> first.
       That is, apps will try to connect to the last <listen> address first.

       tcp sockets can accept IPv4 addresses, IPv6 addresses or hostnames.  If
       a hostname resolves to multiple addresses, the server will bind to  all
       of them. The family=ipv4 or family=ipv6 options can be used to force it
       to bind to a subset of addresses

       Example: <listen>tcp:host=localhost,port=0,family=ipv4</listen>

       A special case is using a port number of zero (or omitting  the	port),
       which  means to choose an available port selected by the operating sys‐
       tem. The port number chosen can be obtained  with  the  --print-address
       command	line  parameter	 and  will be present in other cases where the
       server reports its own address, such as	when  DBUS_SESSION_BUS_ADDRESS
       is set.

       Example: <listen>tcp:host=localhost,port=0</listen>

       tcp  addresses  also  allow a bind=hostname option, which will override
       the host option specifying what address to bind	to,  without  changing
       the  address  reported by the bus. The bind option can also take a spe‐
       cial name '*'  to  cause	 the  bus  to  listen  on  all	local  address
       (INADDR_ANY).  The  specified  host should be a valid name of the local
       machine or weird stuff will happen.

       Example: <listen>tcp:host=localhost,bind=*,port=0</listen>

       <auth>

       Lists permitted	authorization  mechanisms.  If	this  element  doesn't
       exist,  then  all  known mechanisms are allowed.	 If there are multiple
       <auth> elements, all the listed mechanisms are allowed.	The  order  in
       which mechanisms are listed is not meaningful.

       Example: <auth>EXTERNAL</auth>

       Example: <auth>DBUS_COOKIE_SHA1</auth>

       <servicedir>

       Adds  a	directory  to scan for .service files. Directories are scanned
       starting with the last to appear in the config file (the first .service
       file found that provides a particular service will be used).

       Service	files tell the bus how to automatically start a program.  They
       are primarily used with the per-user-session bus,  not  the  systemwide
       bus.

       <standard_session_servicedirs/>

       <standard_session_servicedirs/> is equivalent to specifying a series of
       <servicedir/> elements for each of the data  directories	 in  the  "XDG
       Base  Directory Specification" with the subdirectory "dbus-1/services",
       so for example "/usr/share/dbus-1/services" would be among the directo‐
       ries searched.

       The "XDG Base Directory Specification" can be found at http://freedesk‐
       top.org/wiki/Standards/basedir-spec if it hasn't moved,	otherwise  try
       your favorite search engine.

       The <standard_session_servicedirs/> option is only relevant to the per-
       user-session bus daemon	defined	 in  /usr/pkg/etc/dbus-1/session.conf.
       Putting it in any other configuration file would probably be nonsense.

       <standard_system_servicedirs/>

       <standard_system_servicedirs/> specifies the standard system-wide acti‐
       vation directories that should be searched  for	service	 files.	  This
       option defaults to /usr/pkg/share/dbus-1/system-services.

       The  <standard_system_servicedirs/> option is only relevant to the per-
       system bus daemon defined in  /usr/pkg/etc/dbus-1/system.conf.  Putting
       it in any other configuration file would probably be nonsense.

       <servicehelper/>

       <servicehelper/>	 specifies  the	 setuid	 helper that is used to launch
       system daemons with an alternate user. Typically	 this  should  be  the
       dbus-daemon-launch-helper executable in located in libexec.

       The <servicehelper/> option is only relevant to the per-system bus dae‐
       mon defined in /usr/pkg/etc/dbus-1/system.conf. Putting it in any other
       configuration file would probably be nonsense.

       <limit>

       <limit> establishes a resource limit. For example:
	 <limit name="max_message_size">64</limit>
	 <limit name="max_completed_connections">512</limit>

       The name attribute is mandatory.	 Available limit names are:
	     "max_incoming_bytes"	  : total size in bytes of messages
					    incoming from a single connection
	     "max_outgoing_bytes"	  : total size in bytes of messages
					    queued up for a single connection
	     "max_message_size"		  : max size of a single message in
					    bytes
	     "service_start_timeout"	  : milliseconds (thousandths) until
					    a started service has to connect
	     "auth_timeout"		  : milliseconds (thousandths) a
					    connection is given to
					    authenticate
	     "max_completed_connections"  : max number of authenticated connections
	     "max_incomplete_connections" : max number of unauthenticated
					    connections
	     "max_connections_per_user"	  : max number of completed connections from
					    the same user
	     "max_pending_service_starts" : max number of service launches in
					    progress at the same time
	     "max_names_per_connection"	  : max number of names a single
					    connection can own
	     "max_match_rules_per_connection": max number of match rules for a single
					       connection
	     "max_replies_per_connection" : max number of pending method
					    replies per connection
					    (number of calls-in-progress)
	     "reply_timeout"		  : milliseconds (thousandths)
					    until a method call times out

       The  max incoming/outgoing queue sizes allow a new message to be queued
       if one byte remains below the max. So you can in fact exceed the max by
       max_message_size.

       max_completed_connections  divided  by  max_connections_per_user is the
       number of users that can work together to denial-of-service  all	 other
       users by using up all connections on the systemwide bus.

       Limits  are  normally  only  of interest on the systemwide bus, not the
       user session buses.

       <policy>

       The <policy> element defines a security policy to be applied to a  par‐
       ticular	set  of connections to the bus. A policy is made up of <allow>
       and <deny> elements. Policies are normally  used	 with  the  systemwide
       bus; they are analogous to a firewall in that they allow expected traf‐
       fic and prevent unexpected traffic.

       Currently, the system bus has a default-deny policy for sending	method
       calls  and owning bus names.  Everything else, in particular reply mes‐
       sages, receive checks, and signals has a default allow policy.

       In general, it is best to keep system services as small, targeted  pro‐
       grams  which  run  in  their own process and provide a single bus name.
       Then, all that is needed is an <allow> rule for the "own" permission to
       let  the	 process  claim the bus name, and a "send_destination" rule to
       allow traffic from some or all uids to your service.

       The <policy> element has one of four attributes: daemon.1.in
	 context="(default|mandatory)"
	 at_console="(true|false)"
	 user="username or userid"
	 group="group name or gid"

       Policies are applied to a connection as follows:
	  - all context="default" policies are applied
	  - all group="connection's user's group" policies are applied
	    in undefined order
	  - all user="connection's auth user" policies are applied
	    in undefined order
	  - all at_console="true" policies are applied
	  - all at_console="false" policies are applied
	  - all context="mandatory" policies are applied

       Policies applied later will override those applied  earlier,  when  the
       policies	 overlap.  Multiple  policies with the same user/group/context
       are applied in the order they appear in the config file.

       <deny> <allow>

       A <deny> element appears below a <policy> element  and  prohibits  some
       action.	The  <allow>  element  makes  an  exception to previous <deny>
       statements, and works just like <deny> but with the inverse meaning.

       The possible attributes of these elements are:
	  send_interface="interface_name"
	  send_member="method_or_signal_name"
	  send_error="error_name"
	  send_destination="name"
	  send_type="method_call" | "method_return" | "signal" | "error"
	  send_path="/path/name"

	  receive_interface="interface_name"
	  receive_member="method_or_signal_name"
	  receive_error="error_name"
	  receive_sender="name"
	  receive_type="method_call" | "method_return" | "signal" | "error"
	  receive_path="/path/name"

	  send_requested_reply="true" | "false"
	  receive_requested_reply="true" | "false"

	  eavesdrop="true" | "false"

	  own="name"
	  user="username"
	  group="groupname"

       Examples:
	  <deny send_interface="org.freedesktop.System" send_member="Reboot"/>
	  <deny receive_interface="org.freedesktop.System" receive_member="Reboot"/>
	  <deny own="org.freedesktop.System"/>
	  <deny send_destination="org.freedesktop.System"/>
	  <deny receive_sender="org.freedesktop.System"/>
	  <deny user="john"/>
	  <deny group="enemies"/>

       The <deny> element's attributes determine whether the deny "matches"  a
       particular  action.  If	it matches, the action is denied (unless later
       rules in the config file allow it).

       send_destination and receive_sender rules mean that messages may not be
       sent  to	 or received from the *owner* of the given name, not that they
       may not be sent *to that name*. That is, if a connection owns  services
       A,  B,  C,  and sending to A is denied, sending to B or C will not work
       either.

       The other send_* and receive_* attributes are  purely  textual/by-value
       matches against the given field in the message header.

       "Eavesdropping"	occurs when an application receives a message that was
       explicitly addressed to a name the application does not own,  or	 is  a
       reply  to  such	a message. Eavesdropping thus only applies to messages
       that are addressed to services and replies to such  messages  (i.e.  it
       does not apply to signals).

       For <allow>, eavesdrop="true" indicates that the rule matches even when
       eavesdropping. eavesdrop="false" is the default and means that the rule
       only  allows  messages to go to their specified recipient.  For <deny>,
       eavesdrop="true" indicates that the rule matches only  when  eavesdrop‐
       ping.  eavesdrop="false"	 is  the  default for <deny> also, but here it
       means that the rule applies always, even when  not  eavesdropping.  The
       eavesdrop  attribute  can  only be combined with send and receive rules
       (with send_* and receive_* attributes).

       The [send|receive]_requested_reply attribute  works  similarly  to  the
       eavesdrop  attribute. It controls whether the <deny> or <allow> matches
       a reply that is expected (corresponds to a previous  method  call  mes‐
       sage).	This attribute only makes sense for reply messages (errors and
       method returns), and is ignored for other message types.

       For <allow>, [send|receive]_requested_reply="true" is the  default  and
       indicates  that	only  requested	 replies  are  allowed	by  the	 rule.
       [send|receive]_requested_reply="false" means that the rule  allows  any
       reply even if unexpected.

       For  <deny>,  [send|receive]_requested_reply="false" is the default but
       indicates that the rule matches only when the reply was not  requested.
       [send|receive]_requested_reply="true"  indicates	 that the rule applies
       always, regardless of pending reply state.

       user and group denials mean that the given user or group may  not  con‐
       nect to the message bus.

       For  "name",  "username",  "groupname",	etc.  the character "*" can be
       substituted, meaning  "any."  Complex  globs  like  "foo.bar.*"	aren't
       allowed for now because they'd be work to implement and maybe encourage
       sloppy security anyway.

       It does not make sense to deny a user or group inside a <policy> for  a
       user  or group; user/group denials can only be inside context="default"
       or context="mandatory" policies.

       A single <deny> rule may specify combinations  of  attributes  such  as
       send_destination	 and  send_interface  and send_type. In this case, the
       denial applies only if both attributes match the message being  denied.
       e.g. <deny send_interface="foo.bar" send_destination="foo.blah"/> would
       deny messages with the given interface AND the given bus name.  To  get
       an OR effect you specify multiple <deny> rules.

       You  can't include both send_ and receive_ attributes on the same rule,
       since "whether the  message  can	 be  sent"  and	 "whether  it  can  be
       received" are evaluated separately.

       Be careful with send_interface/receive_interface, because the interface
       field in messages is optional.  In particular,  do  NOT	specify	 <deny
       send_interface="org.foo.Bar"/>!	 This will cause no-interface messages
       to be blocked for all services, which is almost certainly not what  you
       intended.    Always   use   rules   of	the  form:  <deny  send_inter‐
       face="org.foo.Bar" send_destination="org.foo.Service"/>

       <selinux>

       The <selinux> element contains settings related	to  Security  Enhanced
       Linux.  More details below.

       <associate>

       An <associate> element appears below an <selinux> element and creates a
       mapping. Right now only one kind of association is possible:
	  <associate own="org.freedesktop.Foobar" context="foo_t"/>

       This means that if a connection asks to	own  the  name	"org.freedesk‐
       top.Foobar"  then the source context will be the context of the connec‐
       tion and the target context will be "foo_t" - see the short  discussion
       of SELinux below.

       Note,  the  context  here is the target context when requesting a name,
       NOT the context of the connection owning the name.

       There's currently no way to set a default for owning any	 name,	if  we
       add this syntax it will look like:
	  <associate own="*" context="foo_t"/>
       If  you	find  a reason this is useful, let the developers know.	 Right
       now the default will be the security context of the bus itself.

       If two <associate> elements specify the same name, the element  appear‐
       ing later in the configuration file will be used.

SELinux
       See  http://www.nsa.gov/selinux/ for full details on SELinux. Some use‐
       ful excerpts:

	       Every subject (process) and  object  (e.g.  file,  socket,  IPC
	       object, etc) in the system is assigned a collection of security
	       attributes, known as a security	context.  A  security  context
	       contains	 all of the security attributes associated with a par‐
	       ticular subject or object that are  relevant  to	 the  security
	       policy.

	       In order to better encapsulate security contexts and to provide
	       greater efficiency, the policy enforcement code of SELinux typ‐
	       ically handles security identifiers (SIDs) rather than security
	       contexts. A SID is an integer that is mapped  by	 the  security
	       server to a security context at runtime.

	       When  a	security  decision is required, the policy enforcement
	       code passes a pair of SIDs (typically the SID of a subject  and
	       the SID of an object, but sometimes a pair of subject SIDs or a
	       pair of object SIDs), and an object security class to the secu‐
	       rity  server.  The  object security class indicates the kind of
	       object, e.g. a process, a regular  file,	 a  directory,	a  TCP
	       socket, etc.

	       Access decisions specify whether or not a permission is granted
	       for a given pair of SIDs and class. Each object class has a set
	       of  associated  permissions  defined  to	 control operations on
	       objects with that class.

       D-Bus performs SELinux security checks in two places.

       First, any time a message is routed from one connection to another con‐
       nection,	 the  bus daemon will check permissions with the security con‐
       text of the first connection as source, security context of the	second
       connection  as  target,	object	class  "dbus" and requested permission
       "send_msg".

       If a security context is not available  for  a  connection  (impossible
       when  using  UNIX  domain sockets), then the target context used is the
       context of the bus daemon itself.  There is currently no way to	change
       this default, because we're assuming that only UNIX domain sockets will
       be used to connect to the systemwide bus. If this changes, we'll proba‐
       bly add a way to set the default connection context.

       Second,	any  time a connection asks to own a name, the bus daemon will
       check permissions with  the  security  context  of  the	connection  as
       source,	the security context specified for the name in the config file
       as target, object class "dbus" and requested permission "acquire_svc".

       The security context for a bus name is specified with  the  <associate>
       element	described earlier in this document.  If a name has no security
       context associated in the configuration file, the security  context  of
       the bus daemon itself will be used.

DEBUGGING
       If you're trying to figure out where your messages are going or why you
       aren't getting messages, there are several things you can try.

       Remember that the system bus is heavily locked down and if you  haven't
       installed  a  security  policy  file  to allow your message through, it
       won't work. For the session bus, this is not a concern.

       The simplest way to figure out what's happening on the bus  is  to  run
       the  dbus-monitor  program, which comes with the D-Bus package. You can
       also send test messages with dbus-send. These programs have  their  own
       man pages.

       If you want to know what the daemon itself is doing, you might consider
       running a separate copy of the daemon to test against. This will	 allow
       you  to put the daemon under a debugger, or run it with verbose output,
       without messing up your real session and system daemons.

       To run a separate test copy of the daemon, for example you might open a
       terminal and type:
	 DBUS_VERBOSE=1 dbus-daemon --session --print-address

       The  test  daemon  address  will be printed when the daemon starts. You
       will need to copy-and-paste this address and use it as the value of the
       DBUS_SESSION_BUS_ADDRESS	 environment  variable	when  you  launch  the
       applications you want to test. This will cause  those  applications  to
       connect	to  your  test	bus instead of the DBUS_SESSION_BUS_ADDRESS of
       your real session bus.

       DBUS_VERBOSE=1 will have NO EFFECT unless your copy of D-Bus  was  com‐
       piled  with verbose mode enabled. This is not recommended in production
       builds due to performance impact. You may need to rebuild D-Bus if your
       copy  was  not built with debugging in mind. (DBUS_VERBOSE also affects
       the D-Bus library and thus applications using D-Bus; it may  be	useful
       to see verbose output on both the client side and from the daemon.)

       If you want to get fancy, you can create a custom bus configuration for
       your test bus (see the session.conf and system.conf files  that	define
       the  two	 default  configurations for example). This would allow you to
       specify a different directory for .service files, for example.

AUTHOR
       See http://www.freedesktop.org/software/dbus/doc/AUTHORS

BUGS
       Please send bug reports to the D-Bus mailing list or bug	 tracker,  see
       http://www.freedesktop.org/software/dbus/

								dbus-daemon(1)
[top]
                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 
More information is available in HTML format for server NetBSD

List of man pages available for NetBSD

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net