smbd
NAME
smbd - server to provide SMB/CIFS services to clientsSYNOPSIS
smbd [ -D ] [ -a ] [ -o ] [ -P ] [ -h ] [ -V ] [ -d debug_level ] [ -l log_file ] [ -p port_number ] [ -O socket_option ] [ -s configuration_file ]DESCRIPTION
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, Win dows 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 services. Please note that there are significant security implica tions 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 dur ing 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 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 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. -a If this parameter is specified, each new connection will append log messages to the log file. This is the default. -o If this parameter is specified, the log files will be overwritten when opened. By default, smbd will append entries to the log files. -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 critical errors and seri ous warnings will be logged. Level 1 is a reason able level for day to day running - it generates a small amount of information about operations car ried out. Levels above 1 will generate considerable amounts of log data, and should only be used when investi gating 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 over ride the log levelfile. -l <log file> If specified, log file specifies a log filename into which informational and debug messages from the running server will be logged. 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. The default log file name 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 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 ser vices 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 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 descrip tions 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 compile time.FILES
/etc/inetd.conf If the server is to be run by the inetd meta-dae mon, this file must contain suitable startup infor mation for the meta-daemon. See the section INSTAL LATION below. /etc/rc 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 section INSTALLA TION below. /etc/services 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 section INSTAL LATION below. /usr/local/samba/lib/smb.conf This is the default location of the smb.conf server configuration file. Other common places that sys tems 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.LIMITATIONS
On some systems smbd cannot change uid back to root after a setuid() call. Such systems are called trapdoor uid sys tems. 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.ENVIRONMENTVARIABLES
PRINTER If no printer name is specified to printable ser vices, 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 spe cific 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 readable by all, writeable only by root. The server pro gram 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. The server log files should be put in a directory readable and writeable only by root, as the log files may contain sensitive information. The configuration file should be placed in a directory readable and writeable 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 installed in /usr/local/samba/bin · smb.conf 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. For serious use as file server it is recommended that smbd be run as a daemon. 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 initialization script 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.) If the options used at compile time are appropriate for your system, all parameters except -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 NetBIOS name server nmbdat the same time as smbd. To do this refer to the man page for 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. Lastly, edit the configuration file to provide suitable services. To start with, the following two services should be all you need: [homes] writeable = yes [printers] writeable = 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).PAM INTERACTION
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 configu ration files may need a line added for session support.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 and also going through the steps outlined in the file DIAGNOSIS.txt in the docs/ directory of your Samba installation.VERSION
This man page is correct for version 2.2 of the Samba suite.DIAGNOSTICS
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 the time this man page was created, there are too many diagnostics available in the source code to war rant 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
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 by sending it a SIGUSR1 (kill -USR1 <smbd-pid>) and lowered by sending it a SIGUSR2 (kill -USR2 <smbd-pid> ). This is to allow tran sient 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.SEE ALSO
hosts_access(5), inetd(8), nmbd(8), smb.conf(5), smbclient(1), and the Internet RFC's rfc1001.txt, rfc1002.txt. In addition the CIFS (formerly SMB) specifi cation is available as a link from the Web page http://samba.org/cifs/ <URL:http://samba.org/cifs/>.AUTHOR
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, avail able 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 09 July 2001 SMBD(8)