nmbd

nmbd [-D] [-F] [-S] [-H <filename>] [-s <configuration file>] [-d <debug level>] [-l <log directory>] [-V]

-D
    Run nmbd as a daemon in the background. This is the default behavior when run from system init scripts.

-F
    Run nmbd in the foreground. This is useful for debugging or when running under a process supervisor.

-S
    Log output to standard output (stdout) instead of syslog. Typically used in conjunction with -F.

-H <filename>
    Specify the path to the lmhosts file, which provides static NetBIOS name to IP address mappings.

-s <configuration file>
    Specify the path to the Samba configuration file, typically /etc/samba/smb.conf.

-d <debug level>
    Set the debug (log) level. Levels range from 0 (no logging) to 10 (maximum debugging information).

-l <log directory>
    Specify the directory where log files should be written. Overrides the log file parameter in smb.conf.

-V
    Print the nmbd version number and exit.

nmbd is a fundamental daemon within the Samba suite, providing essential NetBIOS over IP (NetBT) name services. It is responsible for handling NetBIOS name registration, resolution, and release requests, which are crucial for Windows clients to locate resources by name on a network. nmbd can function as a Windows Internet Name Service (WINS) server, offering dynamic name resolution, or it can forward resolution requests to an existing WINS server configured in smb.conf.

Beyond name services, nmbd plays a significant role in network browsing. It participates in the election process for the Local Master Browser within a workgroup and maintains the browse list, allowing clients to discover available shares and printers. Its presence ensures that Samba shares are visible and accessible by name to Windows machines, making it indispensable for proper Samba functionality in a Windows-centric environment. It typically runs in the background as a system service.

Firewall Rules: nmbd requires UDP ports 137 (NetBIOS Name Service) and 138 (NetBIOS Datagram Service) to be open on any firewalls for its core functionality.
WINS Configuration: For optimal network performance and to prevent conflicts, it is strongly recommended to have only one active WINS server per subnet. Carefully configure nmbd's WINS role via smb.conf.
smb.conf Dependence: While nmbd has command-line options, its primary behavior, including its role as a WINS server or master browser, is governed by parameters set within the smb.conf configuration file.

nmbd's operational parameters, such as its workgroup, netbios name, whether it acts as a wins support server, or relies on an external wins server, are primarily configured within the [global] section of the smb.conf file. This centralizes Samba's network identity and behavior, making smb.conf the primary control point for nmbd.

nmbd communicates using specific UDP ports: UDP 137 for NetBIOS Name Service (NBNAMES) and UDP 138 for NetBIOS Datagram Service (NBDATAGRAM). These ports are essential for name resolution and browsing functions. Ensure they are not blocked by firewalls on the Samba server or network path.

nmbd has been a core component of the Samba suite since its inception, providing the critical NetBIOS name service and browsing capabilities that allowed Unix/Linux systems to seamlessly integrate into Windows networks. It evolved to support various versions of Windows networking protocols. While initially some behaviors could be controlled via command-line flags, much of its configuration migrated to the central smb.conf file over time, streamlining Samba management. Its ongoing development ensures compatibility with newer Windows versions and network environments, remaining indispensable for Samba's file and print sharing services.

smbd(8), smb.conf(5), testparm(1), net(8), winbindd(8)