smbd [-D] [-a] [-o] [-d debuglevel] [-l log file] [-p port number] [-O socket options] [-s configuration file] [-i scope] [-P] [-h]
This program is part of the Samba suite.
smbd is the server daemon that provides filesharing 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,
Windows NT, OS/2, DAVE for Macintosh, and smbfs for Linux.
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 smb.conf (5)). This man page
will not describe the services, but will concentrate on the
administrative aspects of running the server.
Please note that there are significant security implications to
running this server, and the smb.conf (5) manpage should be
regarded as mandatory reading before proceeding with installation.
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 are closed, the copy of the server for
that client terminates.
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.
By default, the server will NOT operate as a daemon.
The default value if this parameter is not specified is zero.
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.
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.
Note that specifying this parameter here will override the log
level parameter in the smb.conf
(5) file.
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.
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.
This parameter is not normally specified except in the above
situation.
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 smb.conf
(5) for more information.
/etc/inetd.conf
If the server is to be run by the inetd meta-daemon, this file must
contain suitable startup information for the meta-daemon. See the
section INSTALLATION below.
/etc/rc
(or whatever initialisation script your system uses).
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.
/etc/services
If running the server via the meta-daemon inetd, this file must
contain a mapping of service name (eg., netbios-ssn) to service port
(eg., 139) and protocol type (eg., tcp). See the section
INSTALLATION below.
/usr/local/samba/lib/smb.conf
This is the default location of the smb.conf server configuration
file. Other common places that systems install this file are
/usr/samba/lib/smb.conf and /etc/smb.conf.
This file describes all the services the server is to make available
to clients. See smb.conf (5) for more information.
On some systems smbd cannot change uid back to root after a
setuid() call. Such systems are called "trapdoor" 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 "access denied" or similar.
PRINTER
If no printer name is specified to printable services, most systems
will use the value of this variable (or "lp" if this variable is not
defined) as the name of the printer to use. This is not specific to
the server, however.
The location of the server and its support files is a matter for
individual system administrators. The following are thus suggestions
only.
It is recommended that the server software be installed under the
/usr/local/samba 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.
The server log files should be put in a directory readable and
writable only by root, as the log files may contain sensitive
information.
The configuration file should be placed in a directory readable and
writable 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 "smb.conf.sample" is supplied with the source to the server -
this may be renamed to "smb.conf" and modified to suit your needs.
The remaining notes will assume the following:
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 inetd 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 smbd be run
as a daemon.
When you've decided, continue with either RUNNING THE SERVER AS A
DAEMON or RUNNING THE SERVER ON REQUEST.
To run the server as a daemon from the command line, simply put the
-D option on the command line. There is no need to place an
ampersand at the end of the command line - the -D option causes
the server to detach itself from the tty anyway.
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.
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 /etc/rc), insert the
following line, substituting port number, log file location,
configuration file location and debug level as desired:
/usr/local/samba/bin/smbd -D -l /var/adm/smblogs/log -s /usr/local/samba/lib/smb.conf
(The above should appear in your initialisation 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.)
If the options used at compile time are appropriate for your system,
all parameters except the desired debug level and -D may be
omitted. See the section OPTIONS above.
If your system uses a meta-daemon such as inetd, 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.
You will probably want to set up the NetBIOS name server nmbd at
the same time as smbd. To do this refer to the man page for
nmbd (8).
First, ensure that a port is configured in the file /etc/services. The
well-known port 139 should be used if possible, though any port may be
used.
Ensure that a line similar to the following is in /etc/services:
netbios-ssn 139/tcp
Note for NIS/YP users - you may need to rebuild the NIS service maps
rather than alter your local /etc/services file.
Next, put a suitable line in the file /etc/inetd.conf (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 /etc/services. Substitute appropriate values for your system
in this line (see inetd (8)):
netbios-ssn stream tcp nowait root /usr/local/samba/bin/smbd -d1 -l/var/adm/smblogs/log -s/usr/local/samba/lib/smb.conf
(The above should appear in /etc/inetd.conf 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.)
Note that there is no need to specify a port number here, even if you
are using a non-standard port number.
Lastly, edit the configuration file to provide suitable services. To
start with, the following two services should be all you need:
[homes] writable = yes [printers] writable = no printable = yes path = /tmp public = yes
This will allow you to connect to your home directory and print to any
printer supported by the host (user privileges permitting).
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 inetd will reread their configuration
tables if they receive a HUP signal.
If your machine's name is "fred" and your name is "mary", you should
now be able to connect to the service \\fred\mary.
To properly test and experiment with the server, we recommend using
the smbclient program (see smbclient (1)) and also going through
the steps outlined in the file DIAGNOSIS.txt in the docs/
directory of your Samba installation.
This man page is correct for version 2.0 of the Samba suite.
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.
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.
Most messages are reasonably self-explanatory. Unfortunately, at time
of creation of this man page 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.
Sending the smbd a SIGHUP will cause it to re-load its smb.conf
configuration file within a short period of time.
To shut down a users smbd process it is recommended that SIGKILL (-9)
NOT be used, except as a last resort, as this may leave the shared
memory area in an inconsistant 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.
The debug log level of smbd may be raised
by sending it a SIGUSR1 (kill -USR1 <smbd-pid>) and lowered by
sending it a SIGUSR2 (kill -USR2 <smbd-pid>). This is to allow
transient problems to be diagnosed, whilst still running at a normally
low log level.
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.
hosts_access (5), inetd (8), nmbd (8),
smb.conf (5), smbclient
(1), testparm (1),
testprns (1), and the Internet RFC's
rfc1001.txt, rfc1002.txt. In addition the CIFS (formerly SMB)
specification is available as a link from the Web page :
http://samba.anu.edu.au/cifs/.
The original Samba software and related utilities were created by
Andrew Tridgell (samba-bugs@samba.anu.edu.au). Samba is now developed
by the Samba Team as an Open Source project similar to the way the
Linux kernel is developed.
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
ftp://ftp.icce.rug.nl/pub/unix/)
and updated for the Samba2.0 release by Jeremy Allison.
samba-bugs@samba.anu.edu.au.
See samba (7) to find out how to get a full list of contributors
and details on how to submit bug reports, comments etc.