path: root/docs/docbook/smbd.8.sgml

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN">
<refentry id="smbd">

<refmeta>
	<refentrytitle>smbd</refentrytitle>
	<manvolnum>8</manvolnum>
</refmeta>


<refnamediv>
	<refname>smbd</refname>
	<refpurpose>server to provide SMB/CIFS services to clients</refpurpose>
</refnamediv>

<refsynopsisdiv>
	<cmdsynopsis>
		<command>smbd</command>
		<arg choice="opt">-D</arg>
		<arg choice="opt">-a</arg>
		<arg choice="opt">-o</arg>
		<arg choice="opt">-P</arg>
		<arg choice="opt">-h</arg>
		<arg choice="opt">-V</arg>
		<arg choice="opt">-d &lt;debug level&gt;</arg>
		<arg choice="opt">-l &lt;log file&gt;</arg>
		<arg choice="opt">-p &lt;port number&gt;</arg>
		<arg choice="opt">-O &lt;socket option&gt;</arg>
		<arg choice="opt">-s &lt;configuration file&gt;</arg>
	</cmdsynopsis>
</refsynopsisdiv>

<refsect1>
	<title>DESCRIPTION</title>
	<para>This program is part of the Samba suite.</para>

	<para><command>smbd</command> is the server daemon that 
	provides filesharing and printing services to Windows clients. 
	The server provides filespace and printer services to
	clients using the SMB (or CIFS) protocol. This is compatible 
	with the LanManager protocol, and can service LanManager 
	clients.  These include MSCLIENT 3.0 for DOS, Windows for 
	Workgroups, Windows 95/98/ME, Windows NT, Windows 2000, 
	OS/2, DAVE for Macintosh, and smbfs for Linux.</para>

	<para>An extensive description of the services that the 
	server can provide is given in the man page for the 
	configuration file controlling the attributes of those 
	services (see <ulink url="smb.conf.5.html"><filename>smb.conf(5)
	</filename></ulink>.  This man page will not describe the 
	services, but will concentrate on the administrative aspects 
	of running the server.</para>

	<para>Please note that there are significant security 
	implications to running this server, and the <ulink
	url="smb.conf.5.html"><filename>smb.conf(5)</filename></ulink> 
	manpage should be regarded as mandatory reading before 
	proceeding with installation.</para>

	<para>A session is created whenever a client requests one. 
	Each client gets a copy of the server for each session. This 
	copy then services all connections made by the client during 
	that session. When all connections from its client are closed, 
	the copy of the server for that client terminates.</para>

	<para>The configuration file, and any files that it includes, 
	are automatically reloaded every minute, if they change.  You 
	can force a reload by sending a SIGHUP to the server.  Reloading 
	the configuration file will not affect connections to any service 
	that is already established.  Either the user will have to 
	disconnect from the service, or smbd killed and restarted.</para>
</refsect1>

<refsect1>
	<title>OPTIONS</title>

	<variablelist>
		<varlistentry>
		<term>-D</term>
		<listitem><para>If specified, this parameter causes 
		the server to operate as a daemon. That is, it detaches 
		itself and runs in the background, fielding requests 
		on the appropriate port. Operating the server as a
		daemon is the recommended way of running smbd for 
		servers that provide more than casual use file and 
		print services.  This switch is assumed is <command>smbd
		</command> is executed on the command line of a shell.
		</para></listitem>
		</varlistentry>

		<varlistentry>
		<term>-a</term>
		<listitem><para>If this parameter is specified, each new 
		connection will append log messages to the log file.  
		This is the default.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-o</term>
		<listitem><para>If this parameter is specified, the 
		log files will be overwritten when opened.  By default, 
		<command>smbd</command> will append entries to the log 
		files.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-P</term>
		<listitem><para>Passive option. Causes smbd not to 
		send any network traffic out. Used for debugging by 
		the developers only.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-h</term>
		<listitem><para>Prints the help information (usage) 
		for <command>smbd</command>.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-v</term>
		<listitem><para>Prints the version number for 
		<command>smbd</command>.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-d &lt;debug level&gt;</term>
		<listitem><para>debuglevel is an integer 
		from 0 to 10.  The default value if this parameter is 
		not specified is zero.</para>
		
		<para>The higher this value, the more detail will be 
		logged to the log files about the activities of the 
		server. At level 0, only critical errors and serious 
		warnings will be logged. Level 1 is a reasonable level for
		day to day running - it generates a small amount of 
		information about operations carried out.</para>

		<para>Levels above 1 will generate considerable 
		amounts of log data, and should only be used when 
		investigating a problem. Levels above 3 are designed for 
		use only by developers and generate HUGE amounts of log
		data, most of which is extremely cryptic.</para>

		<para>Note that specifying this parameter here will 
		override the <ulink url="smb.conf.5.html#loglevel">log
		level</ulink> parameter in the <ulink url="smb.conf.5.html">
		<filename>smb.conf(5)</filename></ulink> file.</para>
		</listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-l &lt;log file&gt;</term>
		<listitem><para>If specified, <emphasis>log file</emphasis> 
		specifies a log filename into which informational and debug 
		messages from the running server will be logged. The log 
		file generated is never removed by the server although 
		its size may be controlled by the <ulink 
		url="smb.conf.5.html#maxlogsize">max log size</ulink>
		option in the <ulink url="smb.conf.5.html"><filename>
		smb.conf(5)</filename></ulink> file.  The default log 
		file name is specified at compile time.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-O &lt;socket options&gt;</term>
		<listitem><para>See the <ulink 
		url="smb.conf.5.html#socketoptions">socket options</ulink> 
		parameter in the <ulink url="smb.conf.5.html"><filename>smb.conf(5)
		</filename></ulink> file for details.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-p &lt;port number&gt;</term>
		<listitem><para>port number is a positive integer 
		value.  The default value if this parameter is not 
		specified is 139.</para>
		
		<para>This number is the port number that will be 
		used when making connections to the server from client 
		software. The standard (well-known) port number for the 
		SMB over TCP is 139, hence the default. If you wish to 
		run the server as an ordinary user rather than
		as root, most systems will require you to use a port 
		number greater than 1024 - ask your system administrator 
		for help if you are in this situation.</para>
		
		<para>In order for the server to be useful by most 
		clients, should you configure it on a port other 
		than 139, you will require port redirection services 
		on port 139, details of which are outlined in rfc1002.txt 
		section 4.3.5.</para>
		
		<para>This parameter is not normally specified except 
		in the above situation.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term>-s &lt;configuration file&gt;</term>
		<listitem><para>The file specified contains the 
		configuration details required by the server.  The 
		information in this file includes server-specific
		information such as what printcap file to use, as well 
		as descriptions of all the services that the server is 
		to provide. See <ulink url="smb.conf.5.html"><filename>
		smb.conf(5)</filename></ulink> for more information.
		The default configuration file name is determined at 
		compile time.</para></listitem>
		</varlistentry>
	</variablelist>
</refsect1>

<refsect1>
	<title>FILES</title>

	<variablelist>
		<varlistentry>
		<term><filename>/etc/inetd.conf</filename></term>
		<listitem><para>If the server is to be run by the 
		<command>inetd</command> meta-daemon, this file 
		must contain suitable startup information for the 
		meta-daemon. See the section INSTALLATION below.
		</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term><filename>/etc/rc</filename></term>
		<listitem><para>or whatever initialization script your 
		system uses).</para>

		<para>If running the server as a daemon at startup, 
		this file will need to contain an appropriate startup 
		sequence for the server. See the section INSTALLATION 
		below.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term><filename>/etc/services</filename></term>
		<listitem><para>If running the server via the 
		meta-daemon <command>inetd</command>, this file 
		must contain a mapping of service name (e.g., netbios-ssn) 
		to service port (e.g., 139) and protocol type (e.g., tcp). 
		See the section INSTALLATION below.</para></listitem>
		</varlistentry>
		
		<varlistentry>
		<term><filename>/usr/local/samba/lib/smb.conf</filename></term>
		<listitem><para>This is the default location of the 
		<ulink url="smb.conf.5.html"><filename>smb.conf</filename></ulink>
		server configuration file. Other common places that systems 
		install this file are <filename>/usr/samba/lib/smb.conf</filename> 
		and <filename>/etc/smb.conf</filename>.</para>
		
		<para>This file describes all the services the server 
		is to make available to clients. See <ulink url="smb.conf.5.html">
		<filename>smb.conf(5)</filename></ulink>  for more information.</para>
		</listitem>
		</varlistentry>
	</variablelist>
</refsect1>

<refsect1>
	<title>LIMITATIONS</title>
	<para>On some systems <command>smbd</command> cannot change uid back 
	to root after a setuid() call.  Such systems are called 
	&quot;trapdoor&quot; uid systems. If you have such a system, 
	you will be unable to connect from a client (such as a PC) as 
	two different users at once. Attempts to connect the
	second user will result in &quot;access denied&quot; or 
	similar.</para>
</refsect1>

<refsect1>
	<title>ENVIRONMENTVARIABLES</title>

	<variablelist>
		<varlistentry>
		<term>PRINTER</term>
		<listitem><para>If no printer name is specified to 
		printable services, most systems will use the value of 
		this variable (or &quot;lp&quot; if this variable is 
		not defined) as the name of the printer to use. This 
		is not specific to the server, however.</para></listitem>
		</varlistentry>
	</variablelist>
</refsect1>

<refsect1>
	<title>INSTALLATION</title>
	
	<para>The location of the server and its support files 
	is a matter for individual system administrators. The following 
	are thus suggestions only.</para>

	<para>It is recommended that the server software be installed 
	under the <filename>/usr/local/samba/</filename> hierarchy, 
	in a directory readable by all, writeable only by root. The server 
	program itself should be executable by all, as users may wish to 
	run the server themselves (in which case it will of course run 
	with their privileges).  The server should NOT be setuid. On some 
	systems it may be worthwhile to make smbd setgid to an empty group. 
	This is because some systems may have a security hole where daemon 
	processes that become a user can be attached to with a debugger. 
	Making the smbd file setgid to an empty group may prevent
	this hole from being exploited. This security hole and the suggested
	fix has only been confirmed on old versions (pre-kernel 2.0) of Linux
	at the time this was written. It is possible that this hole only
	exists in Linux, as testing on other systems has thus far shown them
	to be immune.</para>

	<para>The server log files should be put in a directory readable and
	writeable only by root, as the log files may contain sensitive
	information.</para>

	<para>The configuration file should be placed in a directory 
	readable and writeable only by root, as the configuration file 
	controls security for the services offered by the server. The 
	configuration file can be made readable by all if desired, but 
	this is not necessary for correct operation of the server and is 
	not recommended. A sample configuration file <filename>smb.conf.sample
	</filename> is supplied with the source to the server - this may 
	be renamed to <filename>smb.conf</filename> and modified to suit 
	your needs.</para>
	
	<para>The remaining notes will assume the following:</para>

	<itemizedlist>
		<listitem><para><command>smbd</command> (the server program) 
		installed in <filename>/usr/local/samba/bin</filename></para>
		</listitem>

		<listitem><para><filename>smb.conf</filename> (the configuration 
		file) installed in <filename>/usr/local/samba/lib</filename></para>
		</listitem>

		<listitem><para>log files stored in <filename>/var/adm/smblogs
		</filename></para></listitem>
	</itemizedlist>

	<para>The server may be run either as a daemon by users 
	or at startup, or it may be run from a meta-daemon such as 
	<command>inetd</command> upon request. If run as a daemon, 
	the server will always be ready, so starting sessions will be
	faster. If run from a meta-daemon some memory will be saved and
	utilities such as the tcpd TCP-wrapper may be used for extra 
	security.  For serious use as file server it is recommended 
	that <command>smbd</command> be run as a daemon.</para>

	<para>When you've decided, continue with either</para>
	
	<itemizedlist>
		<listitem><para>RUNNING THE SERVER AS A DAEMON or</para></listitem>
		<listitem><para>RUNNING THE SERVER ON REQUEST.</para></listitem>
	</itemizedlist>
</refsect1>

<refsect1>
	<title>RUNNING THE SERVER AS A DAEMON</title>

	<para>To run the server as a daemon from the command 
	line, simply put the <emphasis>-D</emphasis> option on the 
	command line. There is no need to place an ampersand at 
	the end of the command line - the <emphasis>-D</emphasis> 
	option causes the server to detach itself from the tty 
	anyway.</para>

	<para>Any user can run the server as a daemon (execute 
	permissions permitting, of course). This is useful for 
	testing purposes, and may even be useful as a temporary 
	substitute for something like ftp. When run this way, however, 
	the server will only have the privileges of the user who ran 
	it.</para>

	<para>To ensure that the server is run as a daemon whenever 
	the machine is started, and to ensure that it runs as root 
	so that it can serve multiple clients, you will need to modify 
	the system startup files. Wherever appropriate (for example, in 
	<filename>/etc/rc</filename>), insert the following line, 
	substituting port number, log file location, configuration file 
	location and debug level as desired:</para>

	<para><command>/usr/local/samba/bin/smbd -D -l /var/adm/smblogs/log 
	-s /usr/local/samba/lib/smb.conf</command></para>

	<para>(The above should appear in your initialization script 
	as a single line.  Depending on your terminal characteristics, 
	it may not appear that way in this man page. If the above appears 
	as more than one line, please treat any newlines or indentation 
	as a single space or TAB character.)</para>

	<para>If the options used at compile time are appropriate for 
	your system, all parameters except <emphasis>-D</emphasis> may 
	be omitted. See the section OPTIONS above.</para>
</refsect1>

<refsect1>
	<title>RUNNING THE SERVER ON REQUEST</title>

	<para>If your system uses a meta-daemon such as <command>inetd
	</command>, you can arrange to have the smbd server started 
	whenever a process attempts to connect to it. This requires several 
	changes to the startup files on the host machine. If you are 
	experimenting as an ordinary user rather than as root, you will 
	need the assistance of your system administrator to modify the 
	system files.</para>

	<para>You will probably want to set up the NetBIOS name server 
	<ulink url="nmbd.8.html"><command>nmbd</command></ulink> at
	the same time as <command>smbd</command>. To do this refer to the 
	man page for <ulink url="nmbd.8.html"><command>nmbd(8)</command>
	</ulink>.</para>

	<para>First, ensure that a port is configured in the file 
	<filename>/etc/services</filename>. The well-known port 139 
	should be used if possible, though any port may be used.</para>

	<para>Ensure that a line similar to the following is in 
	<filename>/etc/services</filename>:</para>

	<para><command>netbios-ssn	139/tcp</command></para>

	<para>Note for NIS/YP users - you may need to rebuild the 
	NIS service maps rather than alter your local <filename>/etc/services
	</filename> file.</para>

	<para>Next, put a suitable line in the file <filename>/etc/inetd.conf
	</filename> (in the unlikely event that you are using a meta-daemon 
	other than inetd, you are on your own). Note that the first item 
	in this line matches the service name in <filename>/etc/services
	</filename>.  Substitute appropriate values for your system
	in this line (see <command>inetd(8)</command>):</para>

	<para><command>netbios-ssn stream tcp nowait root /usr/local/samba/bin/smbd 
	-d1 -l/var/adm/smblogs/log -s/usr/local/samba/lib/smb.conf</command></para>

	<para>(The above should appear in <filename>/etc/inetd.conf</filename> 
	as a single line. Depending on your terminal characteristics, it may 
	not appear that way in this man page.  If the above appears as more 
	than one line, please treat any newlines or indentation as a single 
	space or TAB character.)</para>

	<para>Note that there is no need to specify a port number here, 
	even if you are using a non-standard port number.</para>

	<para>Lastly, edit the configuration file to provide suitable 
	services. To start with, the following two services should be 
	all you need:</para>
	
	<screen>
	<computeroutput>
	[homes]
		writeable = yes

	[printers]
		writeable = no
		printable = yes
		path = /tmp
		public = yes
	</computeroutput>
	</screen>

	<para>This will allow you to connect to your home directory 
	and print to any printer supported by the host (user privileges 
	permitting).</para>
</refsect1>

<refsect1>
	<title>TESTING THE INSTALLATION</title>

	<para>If running the server as a daemon, execute it before 
	proceeding. If using a meta-daemon, either restart the system 
	or kill and restart the meta-daemon. Some versions of 
	<command>inetd</command> will reread their configuration
	tables if they receive a HUP signal.</para>

	<para>If your machine's name is &quot;fred&quot; and your 
	name is &quot;mary&quot;, you should now be able to connect 
	to the service <filename>&bsol;&bsol;fred&bsol;mary</filename>.
	</para>

	<para>To properly test and experiment with the server, we 
	recommend using the <command>smbclient</command> program (see 
	<ulink url="smbclient.1.html"><command>smbclient(1)</command></ulink>) 
	and also going through the steps outlined in the file 
	<filename>DIAGNOSIS.txt</filename> in the <filename>docs/</filename>
	directory of your Samba installation.</para>
</refsect1>

<refsect1>
	<title>VERSION</title>

	<para>This man page is correct for version 2.2 of 
	the Samba suite.</para>
</refsect1>

<refsect1>
	<title>DIAGNOSTICS</title>

	<para>Most diagnostics issued by the server are logged 
	in a specified log file. The log file name is specified 
	at compile time, but may be overridden on the command line.</para>

	<para>The number and nature of diagnostics available depends 
	on the debug level used by the server. If you have problems, set 
	the debug level to 3 and peruse the log files.</para>

	<para>Most messages are reasonably self-explanatory. Unfortunately, 
	at the time this man page was created, there are too many diagnostics 
	available in the source code to warrant describing each and every 
	diagnostic. At this stage your best bet is still to grep the 
	source code and inspect the conditions that gave rise to the 
	diagnostics you are seeing.</para>
</refsect1>

<refsect1>
	<title>SIGNALS</title>

	<para>Sending the smbd a SIGHUP will cause it to 
	re-load its <filename>smb.conf</filename> configuration 
	file within a short period of time.</para>

	<para>To shut down a users smbd process it is recommended 
	that <command>SIGKILL (-9)</command> <emphasis>NOT</emphasis> 
	be used, except as a last resort, as this may leave the shared
	memory area in an inconsistent state. The safe way to terminate 
	an smbd is to send it a SIGTERM (-15) signal and wait for 
	it to die on its own.</para>

	<para>The debug log level of smbd may be raised by sending 
	it a SIGUSR1 (<command>kill -USR1 &lt;smbd-pid&gt;</command>)
	and lowered by sending it a SIGUSR2 (<command>kill -USR2 &lt;smbd-pid&gt;
	</command>). This is to allow transient problems to be diagnosed, 
	whilst still running at a normally low log level.</para>

	<para>Note that as the signal handlers send a debug write, 
	they are not re-entrant in smbd. This you should wait until 
	smbd is in a state of waiting for an incoming smb before 
	issuing them. It is possible to make the signal handlers safe 
	by un-blocking the signals before the select call and re-blocking 
	them after, however this would affect performance.</para>
</refsect1>

<refsect1>
	<title>SEE ALSO</title>
	<para>hosts_access(5), <command>inetd(8)</command>, 
	<ulink url="nmbd.8.html"><command>nmbd(8)</command></ulink>, 
	<ulink url="smb.conf.5.html"><filename>smb.conf(5)</filename>
	</ulink>, <ulink url="smbclient.1.html"><command>smbclient(1)
	</command></ulink>, <ulink url="testparm.1.html"><command>
	testparm(1)</command></ulink>, <ulink url="testprns.1.html">
	<command>testprns(1)</command></ulink>, and the Internet RFC's
	<filename>rfc1001.txt</filename>, <filename>rfc1002.txt</filename>. 
	In addition the CIFS (formerly SMB) specification is available 
	as a link from the Web page <ulink url="http://samba.org/cifs/"> 
	http://samba.org/cifs/</ulink>.</para>
</refsect1>

<refsect1>
	<title>AUTHOR</title>
	
	<para>The original Samba software and related utilities 
	were created by Andrew Tridgell. Samba is now developed
	by the Samba Team as an Open Source project similar 
	to the way the Linux kernel is developed.</para>
	
	<para>The original Samba man pages were written by Karl Auer. 
	The man page sources were converted to YODL format (another 
	excellent piece of Open Source software, available at
	<ulink url="ftp://ftp.icce.rug.nl/pub/unix/">
	ftp://ftp.icce.rug.nl/pub/unix/</ulink>) and updated for the Samba 2.0 
	release by Jeremy Allison.  The conversion to DocBook for 
	Samba 2.2 was done by Gerald Carter</para>
</refsect1>

</refentry>