smbd - server to provide SMB/CIFS services to clients
smbd [ -D ] [ -a ] [ -i ] [ -o ] [ -P ] [ -h ] [ -V ] [ -d
<debug level> ] [ -l <log directory> ] [ -p <port number> ] [ -O
<socket option> ] [ -s <configuration file> ]
This program is part of the Samba suite.
smbd is the server daemon that provides filesharing and printing ser-
vices to Windows clients. The server provides filespace and printer
services to clients using the SMB (or CIFS) protocol. This is compati-
ble 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
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 manda-
tory 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 con-
nections made by the client during that session. When all connections
from its client are closed, the copy of the server for that client ter-
The configuration file, and any files that it includes, are automati-
cally 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.
-D 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 if smbd is executed on the command line of a
-a If this parameter is specified, each new connection will append
log messages to the log file. This is the default.
-i If this parameter is specified it causes the server to run
"interactively", not as a daemon, even if the server is executed
on the command line of a shell. Setting this parameter negates
the implicit deamon mode when run from the command line.
-o If this parameter is specified, the log files will be overwrit-
ten when opened. By default, smbd will append entries to the log
-P Passive option. Causes smbd not to send any network traffic out.
Used for debugging by the developers only.
-h Prints the help information (usage) for smbd.
-v Prints the version number for smbd.
-d <debug level>
debuglevel is an integer from 0 to 10. 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 crit-
ical 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
-l <log directory>
If specified, log directory specifies a log directory into which
the "log.smbd" log file will be created for informational and
debug messages from the running server. The log file generated
is never removed by the server although its size may be con-
trolled by the max log size option in the smb.conf(5) file.
Beware: If the directory specified does not exist, smbd will log
to the default debug log location defined at compile time.
The default log directory is specified at compile time.
-O <socket options>
See the socket options parameter in the smb.conf(5)
file for details.
-p <port number>
port number is a positive integer value. The default value if
this parameter is not specified is 139.
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
-s <configuration file>
The file specified contains the configuration details required
by the server. The information in this file includes server-spe-
cific 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. The default configura-
tion file name is determined at compile time.
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 UNIX_INSTALL.html document for details.
or whatever initialization 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 UNIX_INSTALL.html document for details.
If running the server via the meta-daemon inetd, 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
UNIX_INSTALL.html document for details.
This is the default location of the smb.conf server configura-
tion 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.
If no printer name is specified to printable services, most sys-
tems 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.
Samba uses PAM for authentication (when presented with a plaintext
password), for account checking (is this account disabled?) and for
session management. The degree too which samba supports PAM is
restricted by the limitations of the SMB protocol and the obey pam
restricions smb.conf paramater. When this is set, the following
o Account Validation: All acccesses to a samba server are checked
against PAM to see if the account is vaild, not disabled and is per-
mitted to login at this time. This also applies to encrypted logins.
o Session Management: When not using share level secuirty, users must
pass PAM's session checks before access is granted. Note however,
that this is bypassed in share level secuirty. Note also that some
older pam configuration files may need a line added for session sup-
This man page is correct for version 2.2 of the Samba suite.
One of the common causes of difficulty when installing Samba and SWAT
is the existsnece of some type of firewall or port filtering software
on the Samba server. Make sure that the appropriate ports outlined in
this man page are available on the server and are not currently being
blocked by some type of security software such as iptables or "port
sentry". For more troubleshooting information, refer to the additional
documentation included in the Samba distribution.
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 over-
ridden 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 the
time this man page was created, there are too many diagnostics avail-
able in the source code to warrant describing each and every diagnos-
tic. 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 see-
Sending the smbd a SIGHUP will cause it to reload its smb.conf configu-
ration file within a short period of time.
To shut down a user's smbd process it is recommended that SIGKILL (-9)
NOT be used, except as a last resort, as this may leave the shared mem-
ory 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.
The debug log level of smbd may be raised or lowered using smbcon-
program (SIGUSR[1|2] signals are no longer used in Samba 2.2). 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 wait-
ing 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)
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
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.
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/
<URL:ftp://ftp.icce.rug.nl/pub/unix/>) and updated for the Samba 2.0
release by Jeremy Allison. The conversion to DocBook for Samba 2.2 was
done by Gerald Carter
19 November 2002 SMBD(8)