man pages section 1: User Commands

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Updated: July 2014

nmblookup (1)


nmblookup - NetBIOS over TCP/IP client used to lookup NetBIOS names


nmblookup [-M] [-R] [-S] [-r] [-A] [-h]
[-B <broadcast address>] [-U <unicast address>]
[-d <debug level>] [-s <smb config file>]
[-i <NetBIOS scope>] [-T] [-f] {name}


User Commands                                        NMBLOOKUP(1)

     nmblookup - NetBIOS over TCP/IP client used to lookup
     NetBIOS names

     nmblookup [-M] [-R] [-S] [-r] [-A] [-h]
      [-B <broadcast address>] [-U <unicast address>]
      [-d <debug level>] [-s <smb config file>]
      [-i <NetBIOS scope>] [-T] [-f] {name}

     This tool is part of the samba(7) suite.

     nmblookup is used to query NetBIOS names and map them to IP
     addresses in a network using NetBIOS over TCP/IP queries.
     The options allow the name queries to be directed at a
     particular IP broadcast area or to a particular machine. All
     queries are done over UDP.

         Searches for a master browser by looking up the NetBIOS
         name name with a type of 0x1d. If
          name is "-" then it does a lookup on the special name
         __MSBROWSE__. Please note that in order to use the name
         "-", you need to make sure "-" isn't parsed as an
         argument, e.g. use : nmblookup -M -- -.

         Set the recursion desired bit in the packet to do a
         recursive lookup. This is used when sending a name query
         to a machine running a WINS server and the user wishes
         to query the names in the WINS server. If this bit is
         unset the normal (broadcast responding) NetBIOS
         processing code on a machine is used instead. See
         RFC1001, RFC1002 for details.

         Once the name query has returned an IP address then do a
         node status query as well. A node status query returns
         the NetBIOS names registered by a host.

         Try and bind to UDP port 137 to send and receive UDP
         datagrams. The reason for this option is a bug in
         Windows 95 where it ignores the source port of the
         requesting packet and only replies to UDP port 137.
         Unfortunately, on most UNIX systems root privilege is
         needed to bind to this port, and in addition, if the
         nmbd(8) daemon is running on this machine it also binds
         to this port.

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         Interpret name as an IP Address and do a node status
         query on this address.

     -n|--netbiosname <primary NetBIOS name>
         This option allows you to override the NetBIOS name that
         Samba uses for itself. This is identical to setting the
         blue]netbios name] parameter in the smb.conf file.
         However, a command line setting will take precedence
         over settings in smb.conf.

     -i|--scope <scope>
         This specifies a NetBIOS scope that nmblookup will use
         to communicate with when generating NetBIOS names. For
         details on the use of NetBIOS scopes, see rfc1001.txt
         and rfc1002.txt. NetBIOS scopes are very rarely used,
         only set this parameter if you are the system
         administrator in charge of all the NetBIOS systems you
         communicate with.

         Set the SMB domain of the username. This overrides the
         default domain which is the domain defined in smb.conf.
         If the domain specified is the same as the servers
         NetBIOS name, it causes the client to log on using the
         servers local SAM (as opposed to the Domain SAM).

     -O|--socket-options socket options
         TCP socket options to set on the client socket. See the
         socket options parameter in the smb.conf manual page for
         the list of valid options.

         Print a summary of command line options.

     -B <broadcast address>
         Send the query to the given broadcast address. Without
         this option the default behavior of nmblookup is to send
         the query to the broadcast address of the network
         interfaces as either auto-detected or defined in the
         interfaces parameter of the smb.conf(5) file.

     -U <unicast address>
         Do a unicast query to the specified address or host
         unicast address. This option (along with the -R option)
         is needed to query a WINS server.

         level is an integer from 0 to 10. The default value if
         this parameter is not specified is 0.

         The higher this value, the more detail will be logged to

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User Commands                                        NMBLOOKUP(1)

         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 blue]log level] parameter in the smb.conf file.

         Prints the program version number.

     -s|--configfile <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 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.

         Base directory name for log/debug files. The extension
         ".progname" will be appended (e.g. log.smbclient,
         log.smbd, etc...). The log file is never removed by the

         This causes any IP addresses found in the lookup to be
         looked up via a reverse DNS lookup into a DNS name, and
         printed out before each

         IP address .... NetBIOS name

         pair that is the normal output.

         Show which flags apply to the name that has been looked
         up. Possible answers are zero or more of: Response,
         Authoritative, Truncated, Recursion_Desired,
         Recursion_Available, Broadcast.

         This is the NetBIOS name being queried. Depending upon
         the previous options this may be a NetBIOS name or IP
         address. If a NetBIOS name then the different name types

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User Commands                                        NMBLOOKUP(1)

         may be specified by appending '#<type>' to the name.
         This name may also be '*', which will return all
         registered names within a broadcast area.

     nmblookup can be used to query a WINS server (in the same
     way nslookup is used to query DNS servers). To query a WINS
     server, nmblookup must be called like this:

     nmblookup -U server -R 'name'

     For example, running :

     nmblookup -U -R 'IRIX#1B'

     would query the WINS server for the domain master
     browser (1B name type) for the IRIX workgroup.

     This man page is correct for version 3 of the Samba suite.

     See attributes(5) for descriptions of the following

     |Availability   | service/network/samba |
     |Stability      | Volatile              |
     nmbd(8), samba(7), and smb.conf(5).

     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, available at and updated 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
     DocBook XML 4.2 for Samba 3.0 was done by Alexander Bokovoy.

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User Commands                                        NMBLOOKUP(1)

     This software was built from source available at  The original
     community source was downloaded from

     Further information about this software can be found on the
     open source community website at

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