Starting NTService as a Windows Service

Napatech Link-Capture™ Software and WinPcap-NT Installation Guide for Windows

Napatech SmartNIC
Content Type
Software Installation Guide
Capture Software Version
Link™ Capture Software 12.11

Service mode

Service mode (background mode) is the normal operation mode. In this mode, NTService is running as a Windows service.

You can control NTService in several ways:

  • From an administrator command prompt, using command-line options.
  • Using the shortcuts installed in the Windows Start menu.
  • Using the Windows Services Management Console. NTService appears with the service name Napatech and the display name Napatech Software Suite 64 bit or Napatech Software Suite 32 bit.
    Note: If you start NTService from the Services Management Console, Status will change to Started before the service is completely initialized. If you receive the error message “NT Service is not started” when for instance running one of the Napatech tools, please wait a little while to allow service initialization to complete.

Options for controlling NTService

For NTService to run in service mode, it must be registered as a Windows service. While the Napatech Link-Capture™ Software Windows installer can register NTService as an auto-start service or a manual startup service for you, you can also change the startup type after installation.

You need permissions as a member of the local Administrators group to register, start and stop NTService.

This table shows the options for how to register, start, and stop NTService.

NTService Option Description
–a Registers NTService as an auto-start service. NTService is started automatically at Windows startup.
-i Registers NTService as a manual startup service.
-u Unregisters NTService as a service.
-s Starts NTService in service mode.
-k Stops NTService from running in service mode.
-r Restarts NTService in service mode, reloading the configuration.

To change startup type

You can change the startup type of NTService, for instance using the Windows Services Manager Console, or using the command-line options of NTService.

To change the startup type using NTService command-line options, you must first unregister and then re-register NTService. For instance, to change the startup type to automatic:

NTService -u
NTService -a

Disabling a Napatech SmartNIC

If you disable a Napatech SmartNIC in Windows Device Manager while NTService is running in service mode, you will receive the error message “Your hardware settings have changed. You must restart your computer for these changes to take effect.”

To avoid this situation, stop NTService before you disable a Napatech SmartNIC in Windows Device Manager.

Registry entries for configuration

Installation of the kernel-mode driver Nt3gd.sys will create these registry entries under [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Nt3gd\Parameters\Configuration]:

Key Default Value Values Description
Inifile (empty)   Path and filename of the .ini file to be used by NTService. Overrides the default %NAPATECH3_ROOT%\config\ntservice.ini.
NTPLfile (empty)   Path and filename of a NTPL file to run at NTService startup.
ServiceDebug 0 0..1 Enables logging to the Windows debug monitor.
ReservedDMAPoolSize 232 Measured in MB. Limited by the amount of installed memory. Allocates and reserves memory at Windows startup on NUMA node 0.

You can manually add ReservedDMAPoolSize entries for specific NUMA nodes:

Key Default Value Values Description
ReservedDMAPoolSize[0] ReservedDMAPoolSize[1] . . . ReservedDMAPoolSize[x] (empty) Measured in MB. Limited by the amount of installed memory. Allocates and reserves memory at Windows startup on specific NUMA nodes.

Registry entries for status information

These registry entries under [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Nt3gd\Parameters\status] are updated each time NTService is started:

Key Description
Inifile Path and name of the last used .ini file
NTPLfile Path and name of the last used NTPL file

Log messages and debugging

In order to see any log messages the ntlog tool must be used.

Debugging NTService in service mode can be done by setting the registry key ServiceDebug to 1. Then all logs are printed to a Windows debug monitor, for instance DbgView from Microsoft Sysinternals.