Man Page for SMBD
smbd - provide SMB (aka LanManager) services to clients
smbd [ -D ] [ -a ] [ -d debuglevel ] [ -l log file ] [ -p port number ] [ -O socket options ] [ -s configuration file ]
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. 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 is automatically reloaded if it changes. You can force a reload by sending a SIGHUP to the server.
-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 5. 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. 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.
/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/smb/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.
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.
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 hierarchy, in a directory readable 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 secrity 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/smb smb_conf (the configuration file) installed in /usr/local/smb 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/smb/smbd -D -l /var/adm/smblogs/log -s /usr/local/smb/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 the 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/smb/smbd -d1 -l/var/adm/smblogs/log -s/usr/local/smb/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)).
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.
[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.
The original Samba software and related utilities were created by Andrew Tridgell (Andrew.). Andrew is also the Keeper of the Source for this project. This man page written by Karl Auer (Karl.) See smb_conf(5) for a full list of contributors and details on how to submit bug reports, comments etc.
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