smbd - server to provide SMB/CIFS services to clients
smbd [-D] [-F] [-S] [-i] [-h] [-V] [-b] [-d <debug level>]
[-l <log directory>] [-p <port number(s)>] [-O <socket option>]
[-s <configuration file>]
This program is part of the samba(7) 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 at-
tributes of those services (see smb.conf(5). This man page will not de-
scribe 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 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. Ei-
ther the user will have to disconnect from the service, or smbd killed
-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
-F 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 con-
nection request, but the main process does not exit. This opera-
tion mode is suitable for runningsmbd under process supervisors
such as supervise and svscan from Daniel J. Bernstein’s daemon-
tools package, or the AIX process monitor.
-S If specified, this parameter causessmbd to log to standard out-
put rather than a file.
-i If this parameter is specified it causes the server to run "in-
teractively", 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. smbd also
logs to standard output, as if the -S parameter had been given.
-V Prints the program version number.
-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 for more information. The default configuration
file name is determined at compile time.
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 pa-
rameter in the smb.conf file.
Base directory name for log/debug files. The extension ".prog-
name" will be appended (e.g. log.smbclient, log.smbd, etc...).
The log file is never removed by the client.
Print a summary of command line options.
-b Prints information about how Samba was built.
-p <port number(s)>
port number(s) is a space or comma-separated list of TCP ports
smbd should listen on. The default value is taken from the ports
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).
If the server is to be run by theinetd 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).
This is the default location of the smb.conf(5) server configu-
ration 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.
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 re-
stricted by the limitations of the SMB protocol and the obey pam re-
strictions smb.conf(5) paramater. When this is set, the following re-
· Account Validation: All accesses 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.
· 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 3.0 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 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-
Samba stores it’s data in several TDB (Trivial Database) files, usually
located in /var/lib/samba.
(*) information persistent across restarts (but not necessarily impor-
tant to backup).
NT account policy settings such as pw expiration, etc...
byte range locks
share connections (used to enforce max connections, etc...)
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 output
Windows registry skeleton (connect via regedit.exe)
session information (e.g. support for ’utmp = yes’)
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 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-
trol(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 untilsmbd 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), test-
parm(1), testprns(1), and the Internet RFC’srfc1001.txt, rfc1002.txt.
In addition the CIFS (formerly SMB) specification is available as a
link from the Web page http://samba.org/cifs/.
The original Samba software and related utilities were created by An-
drew 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 up-
dated for the Samba 2.0 release by Jeremy Allison. The conversion to
DocBook for Samba 2.2 was done by Gerald Carter. The conversion to Doc-
Book XML 4.2 for Samba 3.0 was done by Alexander Bokovoy.
Man(1) output converted with