MID Server capabilities

  • Release version: Xanadu
  • Updated August 1, 2024
  • 3 minutes to read
    • Summarize
    Summarized using AI
    This content was generated using new OpenAI-powered functionality. Results are provided on an as is basis and are not guaranteed to be accurate or complete.

    Summary of MID Server capabilities

    MID Server capabilities specify the functions a MID Server can perform within an IP address range, enabling ServiceNow applications to select the most suitable MID Server for tasks such as discovery and orchestration. These capabilities guide the system in matching MID Servers to devices based on protocol and value criteria.

    Show full answer Show less

    Key Features

    • Nmap Capability: Automatically assigned to MID Servers with the Network Mapper (Nmap) scanner installed for credential-less Discovery. This capability cannot be manually added or removed.
    • Capability Values: Capabilities can have no value, a specific string value, or a wildcard (). A blank value allows the MID Server to locate any device using the protocol, while specific values restrict discovery to exact matches. The Resolve DNS capability uses partial string matching to resolve DNS names ending with specified domains.
    • Capability Selection Algorithm: MID Server selection follows an ordered filtering process based on server status, applications, IP range, and capabilities. It attempts exact value matches first, then wildcard matches, and finally checks for the special capability "ALL."
    • Scripted Capability Matching: Certain capabilities like Resolve DNS use scripts to perform flexible value matching. For example, Resolve DNS matches device names based on domain suffixes, allowing automatic IP resolution for devices within specified domains.
    • Management Interface: Capability name and value combinations are visible when configuring MID Servers, helping administrators manage and assign capabilities precisely per MID Server.

    Practical Application for ServiceNow Customers

    By properly configuring MID Server capabilities, you ensure that ServiceNow applications such as Orchestration and Discovery assign the correct MID Server to devices within your network environment. This improves efficiency and accuracy in device discovery and management.

    Understanding capability values and their matching logic allows you to tailor MID Server assignment to specific network segments or device groups, such as targeting particular datacenter regions or subdomains.

    For DNS resolution tasks, the Resolve DNS capability provides automated domain-based IP address resolution, enhancing discovery processes without requiring exact hostname matches.

    Next Steps

    To configure or review MID Server capabilities, navigate to the MID Server configuration and capability management interfaces in your ServiceNow instance. For details on installing or uninstalling Nmap capabilities, refer to the relevant setup documentation.

    MID Server capabilities define the specific functions of a MID Server within an IP address range.

    Nmap capability

    The Nmap capability is only assigned to MID Servers for which the Network Mapper (Nmap) scanner has been installed for credential-less Discovery. This capability cannot be added to or removed from any MID Server manually. For instructions on installing or uninstalling Nmap, see Install and uninstall Nmap on a MID Server

    MID Server capability values

    Capabilities provided in the base system do not have a defined value string. The capability value can be blank, a single value, or a * (wildcard). A MID Server configured to use a capability that has no value can locate any device using that capability's protocol. If a capability has a defined value, the MID Server using that capability finds only those devices using that protocol that match the value string exactly. The exception to this is the Resolve DNS capability, which is configured to resolve any DNS name into an IP address using a partial string match. The * (wildcard) will match a request capability specifying any non-blank value.

    Starting with the Madrid release, the [capability name]:[value] combination appears in the slushbucket when you add a capability to a MID Server. This combination allows you to see all the capabilities that have different values, even if the capability name is the same. For example, if you are using the Cloud Management capability, and you use the value field to specify the us-west logical datacenter on one of the capability records, you can see the combination in the Collection list.

    Capability name and value combination

    MID Server selection

    The MID Server is selected using an algorithm based on the capabilities available. The selector produces a list of suitable MIDs using filters in the following order: server status > applications > IP range > capabilities. The algorithm searches the capabilities in the following sequence and, if a step finds at least one MID server, the remaining steps are skipped:
    1. Exact value match: Find each MID Server containing capabilities with name/value pairs with an exact match to all requested capability name/value pairs. Blank is a valid value. * (wildcard) values are ignored.
    2. Wildcard value match: The same as an exact value match, but also allows a non-blank request value to match MID server capability records containing value *.
    3. Special capability name ALL: Find each MID Server containing the special capability name ALL, ignoring capability's value field.
    Note:
    If the requested capability name does not exist in the ecc_agent_capability table, BadArgumentException is thrown rather than falling back to the ALL capability.

    Scripted MID Server capability value matching

    You can use value tests to create capabilities that find devices using values without requiring exact string matching. Action on these values is controlled by a user-defined script.

    The Resolve DNS capability is provided in the base system and is configured to resolve DNS names into IP addresses for devices whose names end with a specified domain name. The capability Value entered is automatically prefaced with a dot during processing to match domain syntax. This value can contain one or more sub-domains, but must include the end of the domain string. Matching devices must end with the identical syntax. The script for the Resolve DNS capability determines if a device name matches the criteria defined by Value. If a match exists, the platform performs the address resolution automatically. For example, if the value for the Resolve DNS capability is service-now.com, the MID Server with this capability finds lnxlab01.sandiego.service-now.com and dbsrv101.sanjose.service-now.com. If the value is changed to sandiego.service-now.com, then the MID Server finds only lnxlab01.

    Note:
    If Value in the Resolve DNS capability is blank, then all domains match.

    To view the script for evaluating this capability, navigate to MID Server > Capability Value Tests and select Resolve DNS from the list.

    MID capabilities