SMBD(8)
NAME
smbd - provide SMB (aka LanManager) services to clients
SYNOPSIS
smbd [ -D ] [ -a ] [ -d debuglevel ] [ -l log file ] [ -p
port number ] [ -O socket options ] [ -s configuration
file ]
DESCRIPTION
This program is part of the Samba suite.
smbd is a server that can provide most SMB services. The
server provides filespace and printer services to clients
using the SMB protocol. This is compatible with the Lan-
Manager protocol, and can service LanManager clients.
These include MSCLIENT 3.0 for DOS, Windows for Work-
groups, 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 ser-
vices, but will concentrate on the administrative aspects
of running the server.
Please note that there are significant security implica-
tions to running this server, and smb.conf(5) 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 dur-
ing that session. When all connections from its client are
are closed, the copy of the server for that client termi-
nates.
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 connec-
tions to any service that is already established. Either
the user will have to disconnect from the service, or smbd
killed and restarted.
OPTIONS
-D
If specified, this parameter causes the server to oper-
ate as a daemon. That is, it detaches itself and runs
in the background, fielding requests on the appropriate
port.
By default, the server will NOT operate as a daemon.
-a
If this parameter is specified, the log files will be
overwritten with each new connection. By default, the
log files will be appended to.
-d debuglevel
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.
-l log file
If specified, logfile specifies a base filename into
which operational data from the running server will be
logged.
The default base name is specified at compile time.
The base name is used to generate actual log file
names. For example, if the name specified was "log",
the following files would be used for log data:
log.debug (containing debugging information)
log.in (containing inbound transaction data)
log.out (containing outbound transaction data)
The log files generated are never removed by the
server.
-O socket options
See the socket options section of smb.conf(5) 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 server 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.
-s configuration file
The default configuration file name is determined at
compile time.
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.
FILES
/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., net-
bios-ssn) to service port (eg., 139) and protocol type
(eg., tcp). See the section "INSTALLATION" below.
/usr/local/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.
LIMITATIONS
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.
ENVIRONMENT VARIABLES
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.
INSTALLATION
The location of the server and its support files is a mat-
ter 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 read-
able 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 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 opera-
tion of the server and is not recommended. A sample con-
figuration 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:
smbd (the server program) installed in
/usr/local/samba/bin
smb.conf (the configuration file) installed in
/usr/local/samba/lib
log files stored in /var/adm/smblogs
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.
When you've decided, continue with either "RUNNING THE
SERVER AS A DAEMON" or "RUNNING THE SERVER ON REQUEST".
RUNNING THE SERVER AS A DAEMON
To run the server as a daemon from the command line, sim-
ply 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 permis-
sions 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 mod-
ify the system startup files. Wherever appropriate (for
example, in /etc/rc), insert the following line, substi-
tuting 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 characteris-
tics, it may not appear that way in this man page. If the
above appears as more than one line, please treat any new-
lines 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.
RUNNING THE SERVER ON REQUEST
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 name server nmbd at
the same time as smbd - refer to the man page 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 privi-
leges permitting).
TESTING THE INSTALLATION
If running the server as a daemon, execute it before pro-
ceeding. 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 recom-
mend using the smbclient program (see smbclient(1)).
VERSION
This man page is (mostly) correct for version 1.9.00 of
the Samba suite, plus some of the recent patches to it.
These notes will necessarily lag behind development of the
software, so it is possible that your version of the
server has extensions or parameter semantics that differ
from or are not covered by this man page. Please notify
these to the address below for rectification.
SEE ALSO
hosts_access(5) inetd(8) nmbd(8) smb.conf(5) smb-
client(1) testparm(1) testprns(1) rfc1001.txt
rfc1002.txt
DIAGNOSTICS
[This section under construction]
Most diagnostics issued by the server are logged in a
specified log file. The log file name is specified at com-
pile 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. Unfortu-
nately, at time of creation of this man page the source
code is still too fluid 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.
SIGNALS
In version 1.9.18 and above the debug log level of smbd
may be raised by sending it a SIGUSR1 (kill -USR1 ). 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 perfor-
mance.
BUGS
None known.
CREDITS
The original Samba software and related utilities were
created by Andrew Tridgell samba-bugs@samba.anu.edu.au.
Andrew is also the Keeper of the Source for this project.
See smb.conf(5) for a full list of contributors and
details on how to submit bug reports, comments etc.