---
sourceDocument: Brazil IT Operations Management
sourceDocumentLink: https://www.servicenow.com/docs/r/it-operations-management

 Release :

    - brazil

ft:locale :

    - en-US

ft:publication_title :

    - Brazil IT Operations Management

ft:clusterId :

    - itom

bundleId :

    - itom

workflow :

    - Technology


---

# Credential-less host Discovery

# Credential-less host Discovery {#ariaid-title1}

Release version: Brazil  
Updated September 10, 2026  
![](https://www.servicenow.com/docs/portal-asset/ico-clock) 2 minutes to read
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## Summary of Credential-less host Discovery

Credential-less host Discovery in ServiceNow occurs when a scanned host is detected as alive but inactive, or when all credential-based probes fail.
This process enables discovery of hosts without needing credentials, helping you identify and create or update configuration items (CIs) for these hosts in the CMDB.
Show full answer Show less  
The discovery is triggered by the Shazzam probe or Service Mapping's HorizontalDiscoveryProbe, which launches the Credentialless Discovery Network Device pattern. This pattern attempts to create or update host CIs in the **Hardware \[cmdbcihardware\]** table.

To enable this feature, the system property **mid.discovery.credentialless.enable** must be set to true.

## How Credential-less Discovery Works

* **Nmap Command:** Executed on the MID Server, Nmap checks if the host is up using the IP address and a list of ports, performing reverse DNS to identify host names.
* **Host Identification:** The first hostname returned by Nmap is used; if none, the IP address becomes the host CI name.
* **Operating System Detection:** The Npcap library identifies the host OS family.
* **MAC Address:** If the scanned host is on the same subnet as the Windows MID Server, Nmap returns the MAC address.

The list of ports scanned by Nmap is stored in the **IP Service \[cmdbipservice\]** table, editable by customers. You can disable scanning specific ports by setting the Credentialless Discovery column to false.

## Creating and Updating Host CIs

After discovery, the **SetCredentialLessDeviceClassName** MID Server script sets the host CI's operating system family and assigns the appropriate CI class. Supported OS families include AIX, HP-UX, Linux, Solaris, OS X/iOS, Windows, or else the generic Hardware base class is used.

When credentials become available and credential-based discovery runs again, it updates the existing host CI created by credential-less discovery using serial number, host name, and system class.

## Hardware Identification

The Discovery - IP Based plugin adds an identifier rule to the Hardware base table to match host CI names found by Nmap scans. This rule supports both credential-based and credential-less discovery processes to accurately identify hardware CIs.

## Practical Benefits for ServiceNow Customers

* Enables discovery of hosts even when credentials are unavailable or probes fail, ensuring broader and more complete CMDB coverage.
* Automatically creates or updates hardware CIs, maintaining accurate asset records without manual intervention.
* Allows customization of scanned ports for Nmap, enhancing security and compliance control over discovery activities.
* Supports multiple common operating system families, providing detailed classification of discovered hosts.  
Credential-less host discovery occurs when a scanned host is found to be alive, but not
active, or when all configured credential-based classification probes have failed.

## How the host Discovery pattern is launched {#credential-less-host-discovery__section_z5w_mgp_sbb}

If the Shazzam probe scans a host that is alive but not active, and if credential-based classification probes fail, horizontal Discovery launches the Credentialless Discovery Network Device pattern to gather host information. If the host being scanned does not have a CI defined, Service Mapping launches the HorizontalDiscoveryProbe probe, which in turn launches the Credentialless Discovery Network Device pattern. This pattern attempts to create a new CI if one does not already exist for the scanned host or to update an existing CI in the Hardware \[cmdb_ci_hardware\] table.  
Important:  
To allow the Credentialless Discovery Network Device pattern to launch, ensure that the mid.discovery.credentialless.enable system property is set to true. To disable, ensure this property is set to false.

|-|
| The system creates these entries in the ECC queue during execution of the HorizontalDiscoveryProbe. Figure 1. Credential-less Discovery |
[Table 1. ECC Queue entries]

{#credential-less-host-discovery__table_lbt_4ng_5bb}

|-|
| These log messages are published during execution of the HorizontalDiscoveryProbe.Figure 2. Credential-less host identifier |
[Table 2. Log messages]

{#credential-less-host-discovery__table_als_h4g_5bb}

## The Nmap command {#credential-less-host-discovery__section_vrw_m3t_mbb}

The Nmap command executed on the MID Server determines if the host is up. Using the IP address and a list of ports passed to Nmap by the pattern, Nmap performs reverse DNS name resolution to identify the host name associated with the IP address. If multiple host names are configured, the first name returned by Nmap is used. If no host name is configured, then the IP address of the remote host is used to create the host CI. The Npcap packet capture library, included with the Nmap installation, identifies the host operating system family. If the scanned host is located on the same subnet as the Windows MID Server host that executes Nmap, the remote host's MAC address is returned.  
Note:  
The list of ports that Nmap is configured to scan during credential-less host Discovery is stored in the IP Service \[cmdb_ip_service\] table, which is editable. By default, all ports are available for scanning. To block the use of any port for an Nmap scan, set the value in the Credentialless Discovery \[cl_discovery\] column to false.
Figure 3. Credential-less port list

## Creating or updating host CIs {#credential-less-host-discovery__section_fyc_t1y_mbb}

After successful execution of the Credentialless Discovery Network Device pattern, the SetCredentialLessDeviceClassName MID Server script runs to identify the operating system family of the discovered host. The system class of the host CI is based on the operating system family that is returned by Nmap. If the OS family matches one of the six supported server operating systems, then the system uses a server class derived from the Hardware \[cmdb_ci_hardware\] base class, such as Linux Server \[cmdb_ci_linux_server\]. If no match is found, the system uses the base class.  
Note:  
When the issue with the credentials is resolved and Discovery runs again, the instance uses the serial number, host name, and system class provided by credential-based discovery to update the host CI that was created by credential-less Discovery.
{#credential-less-host-discovery__table_lbg_tdy_mbb__entry__2}

| OS family | CI table |
|-|-|
| AIX | cmdb_ci_aix_server |
| HP-UX | cmdb_ci_hpux_server |
| Linux | cmdb_ci_linux_server |
| Solaris | cmdb_ci_solaris_server |
| OS X or iOS | cmdb_ci_osx_server |
| Windows | cmdb_ci_win_server |
| Undefined | cmdb_ci_hardware |
[Table 3. Supported OS families]

{#credential-less-host-discovery__table_lbg_tdy_mbb}

## Hardware identification {#credential-less-host-discovery__section_ejw_s5n_5bb}

The Discovery - IP Based \[com.snc.discovery.ip_based\] plugin adds an identifier to the Hardware Rule for the Hardware \[cmdb_ci_hardware\] base table that matches on the host CI name for Nmap scans. The Hardware Rule is used by both credential-based and credential-less Discovery.Figure 4. Credential-less hardware rule