smbd - server to provide SMB/CIFS services to clients
smbd [-D|--daemon] [-F|--foreground] [-S|--log-stdout]
[-i|--interactive] [-V] [-b|--build-options]
[-d <debug level>]
[-l|--log-basename <log directory>]
[-p <port number(s)>]
[-P <profiling level>]
[-s <configuration file>] [--no-process-group]
This program is part of the samba(7) 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) manual page 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
The configuration file, and any files that it includes, are
automatically reloaded every three minutes, if they change. One 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
Instead of sending a SIGHUP signal, a request to reload
configuration file may be sent using smbcontrol(1) program.
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 specified, this parameter causes the main smbd process
to not daemonize, i.e. double-fork and disassociate with the terminal. Child
processes are still created as normal to service each connection request, but
the main process does not exit. This operation mode is suitable for running
smbd under process supervisors such as supervise and svscan from Daniel J.
Bernstein's daemontools package, or the AIX process monitor.
If specified, this parameter causes smbd to log to
standard output rather than a file.
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
daemon mode when run from the command line. smbd will only accept one
connection and terminate. It will also log to standard output, as if the -S
parameter had been given.
is an integer from 0 to 10. The default
value if this parameter is not specified is 0.
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 file.
Prints the program version number.
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 for more information.
The default configuration file name is determined at compile time.
Base directory name for log/debug files. The extension
".progname" will be appended (e.g. log.smbclient, log.smbd,
etc...). The log file is never removed by the client.
Set the smb.conf(5)
"<name>" to value "<value>" from the command
line. This overrides compiled-in defaults and options read from the
Print a summary of command line options.
Display brief usage message.
Do not create a new process group for smbd.
Prints information about how Samba was built.
is a space or comma-separated list
of TCP ports smbd should listen on. The default value is taken from the
parameter in smb.conf
The default ports are 139 (used for SMB over NetBIOS over TCP) and
port 445 (used for plain SMB over TCP).
profiling level is a number specifying the level
of profiling data to be collected. 0 turns off profiling, 1 turns on counter
profiling only, 2 turns on complete profiling, and 3 resets all profiling
If the server is to be run by the inetd meta-daemon, this
file must contain suitable startup information for the meta-daemon.
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.
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).
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
This is the default location of the smb.conf(5)
server configuration file. Other common places that systems install this file
are /usr/samba/lib/smb.conf and /etc/samba/smb.conf.
This file describes all the services the server is to make
available to clients. See smb.conf(5) for more information.
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 restrictions smb.conf(5)
parameter. When this is set, the following restrictions apply:
This man page is part of version 4.13.2 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
•Account Validation: All accesses to a
samba server are checked against PAM to see if the account is valid, not
disabled and is permitted to login at this time. This also applies to
•Session Management: When not using share
level security, users must pass PAM's session checks before access is granted.
Note however, that this is bypassed in share level security. Note also that
some older pam configuration files may need a line added for session
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.
Samba stores it's data in several TDB (Trivial Database) files, usually located
(*) information persistent across restarts (but not necessarily
important to backup).
NT account policy settings such as pw expiration,
byte range locks
generic caching db
group mapping information
share modes & oplocks
bad pw attempts
Samba messaging system
cache of user net_info_3 struct from net_samlogon()
request (as a domain member)
installed printer drivers
installed printer forms
installed printer information
directory containing tdb per print queue of cached lpq
Windows registry skeleton (connect via regedit.exe)
session information (e.g. support for 'utmp = yes')
share connections (used to enforce max connections,
open file handles (used durable handles, etc...)
winbindd's cache of user lists, etc...
winbindd's local idmap db
wins database when 'wins support = yes'
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
The debug log level of smbd may be raised or lowered using
smbcontrol(1) program (SIGUSR[1|2] signals are no longer used since
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.