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 terminates.
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 restarted.
Instead of sending a SIGHUP signal, a request to reload configuration file may be sent using smbcontrol(1) program.
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 m[blue]log levelm parameter in the smb.conf file.
The default ports are 139 (used for SMB over NetBIOS over TCP) and port 445 (used for plain SMB over TCP).
If running the server as a daemon at startup, this file will need to contain an appropriate startup sequence for the server.
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.
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 m[blue]obey pam restrictionsm smb.conf(5) parameter. When this is set, the following restrictions apply:
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.
Samba stores it's data in several TDB (Trivial Database) files, usually located in /var/lib/samba.
(*) information persistent across restarts (but not necessarily important to backup).
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 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.
hosts_access(5), inetd(8), nmbd(8), smb.conf(5), smbclient(1), testparm(1), and the Internet RFC's rfc1001.txt, rfc1002.txt. In addition the CIFS (formerly SMB) specification is available as a link from the Web page https://www.samba.org/cifs/.
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.