smbd -- server to provide SMB/CIFS services to clients
smbd [-D] [-a] [-i] [-o] [-P] [-h] [-V] [-b] [-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 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.
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 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.
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 shell.
If this parameter is specified, each new
connection will append log messages to the log file.
This is the default.
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
If this parameter is specified, the
log files will be overwritten when opened. By default,
smbd will append entries to the log
Passive option. Causes smbd not to
send any network traffic out. Used for debugging by
the developers only.
Prints the help information (usage)
Prints the version number for
Prints information about how
Samba was built.
- -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 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.
- -l <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 controlled 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
- -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
This parameter is not normally specified except
in the above situation.
- -s <configuration file>
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.
The default configuration file name is determined at
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
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
server configuration file. Other common places that systems
install this file are /usr/samba/lib/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
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.
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 restrictions apply:
Account Validation: All acccesses to a
samba server are checked
against PAM to see if the account is vaild, not disabled and is permitted to
login at this time. This also applies to encrypted logins.
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 support.
This man page is correct for version 2.2 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 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.
Sending the smbd a SIGHUP will cause it to
reload its smb.conf configuration
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
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.
The debug log level of smbd may be raised
or lowered using smbcontrol(1)
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 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.
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/) and updated for the Samba 2.0
release by Jeremy Allison. The conversion to DocBook for
Samba 2.2 was done by Gerald Carter