Configuring discovery settings

You can configure Discovery settings by using the Discovery Settings page.

To configure Discovery settings


  1. From the main menu, click the Administration icon. The Administration page opens. 
  2. In the Discovery section, click Discovery Configuration.
  3. Any settings that are not set by default are highlighted by a red change bar. The page is grouped into the following sections according to the type of settings:
  4. Make any required changes to the settings on this page and click Apply.
  5. To cancel any of your changes, click Reset To Defaults.

Ports

This section contains settings related to the ports that discovery uses.

Field Name

Details

TCP ports to use for initial scan

Enter the TCP ports that will be scanned on a first scan. Use this setting to prevent scanning of any ports that you want to avoid.
The default is to use ports 21, 22, 23, 80, 135, 443, 513, 902, 3940, 5988 and 5989.
See the notes about Order of operations and TCP and UDP ports to use for initial scan.
Older versions included port 514, which can now be removed from upgraded systems.

UDP ports to use for initial scan

Enter the UDP ports that will be scanned on a first scan. Use this setting to prevent scanning of any ports that you want to avoid. The default is port 161.
See the notes about Order of operations and TCP and UDP ports to use for initial scan.

SSH ports

The default is port 22. Enter any custom ports to scan in a comma-separated list in the Change To column.

RLogin ports

Only the default port 513 is supported so must be empty or 513.

Windows ports

Only the default port 135 is supported so must be empty or 135.

Telnet ports

The default is port 23. Enter any custom ports to scan in a comma-separated list in the Change To column.

FTP ports

The default is port 21. Enter any custom ports to scan in a comma-separated list in the Change To column.

SNMP ports

The default is port 161. Enter any custom ports to scan in a comma-separated list in the Change To column.

HTTP ports

The default is port 80. Enter any custom ports to scan in a comma-separated list in the Change To column.

HTTPS ports

The default is port 443. Enter any custom ports to scan in a comma-separated list in the Change To column.

VMware Authentication Daemon ports

Only the default port 902 is supported so must be empty or 902.

Mainframe Host Server ports

The default is port 3940. Enter any custom ports to scan in a comma-separated list in the Change To column.

WBEM HTTP ports

The default is port 5988. Enter any custom ports to scan in a comma-separated list in the Change To column.

WBEM HTTPS ports

The default is port 5989. Enter any custom ports to scan in a comma-separated list in the Change To column.

Valid Port States

When nmap runs port scans, it returns a result of open, closed, or filtered. Using the check boxes, you can choose which states are valid to investigate further.
• open|filtered—Discover a device that should be accessible but is not. It might be open or filtered.
• filtered—This port is open, but you still cannot connect to it. It must be filtered.
A port for which a result of open is returned is always considered valid.

Check port 135 before using Windows access methods

On Windows computers, port 135 is usually open. Selecting Yes for this option means that nmap checks whether port 135 is open before a Windows proxy is used to discover an IP device. The default is open.
In firewalled environments where a ping might be filtered by a firewall but the Windows proxy might be able to connect to the target (for example, it is part of the same Workgroup), select No.

Device identification

This section contains settings related to the methods that discovery uses to identify devices.

Field Name

Details

Use last login method

Discovery uses the discovery method recorded as having been used successfully for an IP address.

Use SNMP SysDescr to identify OS

Discovery attempts to query the host's SNMP service for the SysDescr value to determine the OS.

Always try "public" SNMP community when using SNMP to identify OS

Discovery attempts to use the public SNMP community to query the host's SNMP service if no credential is available for that host. In this case, only device classification is possible.

Use Host Server to identify mainframes

Discovery attempts to connect to the host server port to determine whether the discovery target is a mainframe computer.

Use Telnet banner to identify OS

Discovery makes a Telnet connection to a host and uses the Telnet "welcome" banner to determine host and OS information.

Use HTTP(S) HEAD request to identify OS

Discovery attempts to connect to port 80 or 443 of the host and perform an HTTP or HTTPS HEAD request to determine the host and OS.

Use FTP banner to identify OS

Discovery starts an FTP session with the host and use the FTP "welcome" banner to determine host and OS information.

Use vSphere API to identify OS

Discovery makes a TCP connection to examine the header and ensure that the VMware authentication daemon is really on port 902 (or the specified port). When confirmed, Discovery makes a webservices request. This type of request requires an open VMware authentication daemon and HTTPS port, and a valid vSphere credential.

Use IP Fingerprinting to identify OS

This option controls whether discovery will use IP fingerprinting to determine the OS, if previous methods have been unsuccessful.
You can configure the network ports scanned during this phase of discovery. See Setting up ports for OS fingerprinting.
The process of IP fingerprinting can cause instability in some legacy systems, and might trigger intrusion detection systems. This option is enabled by default.

Use open ports to identify OS

This option controls whether open ports are used to identify the OS.

Discovery sessions

This section contains settings related to the way in which discovery uses sessions to log in and run commands.

Field Name

Details

Session line delay

A delay of 10 ms is introduced between each line sent by Discovery. This avoids problems where remote shells are unable to cope with rapid command sequences. Select one of the following from the list: 1, 2, 5, 10 (the default), 15, 20, 25, 50, 100 milliseconds.

Session login timeout

The length of time for the discovery script to wait for a login prompt. If the timeout is exceeded, the attempt is abandoned.
• Use the default timeout.
• 10, 20, 30, 60, 90, 120, or 180 seconds.

Maximum search window size

The amount of data to examine when detecting the shell command prompt. The default value is 512 bytes.

Warning: Changing the default value may cause significant degradation of appliance performance. Do not change this value unless directed by Customer Support.

Authorised prompt

Certain systems require an authorization step after login. At the command line, you are prompted to enter session details. The required response is usually a user name and some other information.
In the Authorised Prompt field, enter the text of the prompt.

Authorised response

Where an Authorised Prompt has been entered, you must enter the expected response (that you would enter at the command line) in the Authorised Response field.

Scanning

This section contains settings related to any scanning that discovery undertakes.

Field Name

Details

Ping hosts before scanning 

Use TCP ACK ping before scanning

Ping addresses with TCP ACK packets to determine which hosts are actually up. Use this option when scanning networks that do not permit ping packets. You can specify multiple ports in a comma-separated list.
This option is available only if the Ping hosts before scanning option is set to Yes.
• See the note about Order of operations.
If Use TCP ACK ping before scanning in your discovery settings is set to Yes, BMC Discovery might report a device that does not exist on the network, rather than dark space (NoResponse) under the following conditions:
• BMC Discovery pings an IP address for which there is no device, and
• A firewall in your environment is configured to respond for that IP address
To avoid this issue, BMC recommends that you either alter such firewall configurations or not enable TCP ACK ping.

Use TCP SYN ping before scanning

Exclude ranges from ping

Enter a list of IP addresses or IP address ranges that you do not want to ping. For example, you might want to scan IP addresses that are behind a firewall that blocks ICMP packets. If BMC Discovery pings an IP address and receives no response, it makes no further attempt to scan that IP address. Excluding a range from pinging enables you to scan IP addresses behind such firewalls.
This option affects scanning only of networks other than the one on which the appliance is physically located.

Scan retries

Number of retries to be attempted on each host. The system will retry only for machines on which the OS cannot be determined.
The Scan retries and Default OS options work together in sequence to help locate host machines.

Scan timeout

Timeout (in minutes) that applies when BMC Discovery uses nmap to determine open ports or performs OS fingerprinting. Scan timeout is not used to limit the time to scan devices. See also the credential timeout for the sessions.

Minimum time before end of window to avoid starting new scheduled discovery operations

A discovery run can take some time to complete. If it is started too close to the end of a Discovery window, it does not finish before the end of the window. To prevent this issue, you can specify a period in which discovery runs are not started. The default is 30 minutes, meaning that no discovery runs are started within 30 minutes of the end of a discovery window. Select the period from the following values in the list: 5, 10, 15, 20, 25, 30, 35, 40, and 45 minutes.

Allow scans even if no window defined

Enables you to permit scanning outside permitted discovery windows. The default is no.

Enable running of arbitrary commands

This option controls whether arbitrary commands can be run. Disabling this option prevents many patterns from retrieving information needed to build SIs and BAIs. The default is Yes.

Discover Desktop Hosts

Use this option to permit or prevent discovery of desktop hosts. The default is No; that is, do not discover desktop hosts. When this option is set to No, if a Windows or Mac OS host is determined to be the desktop, the host is skipped. An SMB query is used to determine whether the endpoint is a Windows desktop. See Dark space scanning for more information. When a host is skipped, the device_type attribute on the Device Info node is set to Desktop, no inferred host is created, and the corresponding DiscoveryAccess result is shown as "Skipped (Desktop host discovery has been disabled)."

Discover neighbor information when scanning network devices

Causes discovery to retrieve MAC and port information from neighboring scanned network devices. The default is Yes. Select No only if you do not want to collect any edge connectivity information.

Restore Scan StatusIf enabled, scanning is enabled and you have a vault with either no passphrase or a saved passphrase the system will restart scanning when services are restarted. In all other cases restarting services will result in scanning being disabled.

SQL connections

This section describes settings related to SQL integrations.

Field Name

Details

Timeout to establish a connection

The timeout for establishing a connection to the database. Select the timeout period in seconds from the following values in the list: 5, 10, 30 (the default), 60, 90, 120, and 180.

Maximum connections held open

Specifies the number of connections to databases that can be held open after they would otherwise be closed. Higher values can reduce connection delays but will consume extra resources. The default is Unlimited. Select the number of connections from the following values in the list: 0, 10, 20, 30, 40, 50, and Unlimited.

Maximum time to hold an unused connection open

Specifies the maximum time to hold an unused database connection open. Higher values can reduce connection delays but will consume extra resources. The default is 2 minutes. Select the timeout period in minutes from the following values in the list: 2, 4, 6, 8, and 10.

Mainframe

This section contains settings related to mainframe discovery.

Field Name

Details

Timeout to establish a connection

The timeout for establishing a connection to the database. Select the timeout period in seconds from the following values in the list: 30, 60, 90, 120 (the default), 180, and 300.


Implicit scans

This section contains settings related to implicit scans.

Field Name

Details

Maximum concurrent requests against vCenter

The maximum number of concurrent requests that will be made against individual vCenter servers. Select the maximum number from the following values in the list: 1, 3, 5,7, 10, 15, 20 (the default), 25, and 30.


Other Settings

This section contains other discovery settings.


Field Name

Details

Recording mode

Record and playback modes are intended for diagnostic support and testing. Select one of the following discovery modes from the list:
Off—The normal type of discovery in which the appliance scans IP address ranges on the network, runs scripts on targets, and uses Reasoning to process the results. In this mode, pool data is not created. This mode is the default.
Record—Record mode is the same as Normal mode, but in addition, the raw discovered data is stored on the appliance so that it can be used in Playback mode. In this mode, pool data is created in addition to record data. Creating record and pool data imposes considerable overhead on the system and is rarely needed.
Playback—In Playback mode, data that has been recorded in Record mode is used to replay discovery. In this mode, Discovery does not scan any targets on the network.

Maximum concurrent discovery requests per engine

Specifies the maximum number of concurrent discovery requests permitted per processing engine. The maximum value and available range of settings is calculated for optimum performance depending on the appliance. Values shown in the list depend on the number of processing engines. The base values in the list are 30 (default), 60, 90, 120, and 150.
Values shown are the base values multiplied by the number of processing engines.
If you change this option, you must restart the tideway service.
Leave this setting at its default unless you have many discovery commands timing out. As a general rule, for more discovery requests permitted concurrently, you increase network traffic, and the absolute time for discovering a single host increases. However, total throughput might be improved with the interleaving of discovery processing.

Trade discovery performance with interactivity

Scanning IP addresses, consolidation, and manual pattern execution can place a heavy load on the system. During such times, the UI can become unresponsive. You can choose to delay these tasks to provide additional resources for the UI. Doing so provides better interactivity with the system, but at a cost in raw discovery performance. You can choose from the following options:
• Prefer discovery—The default and the behavior of previous versions of BMC Discovery.
• Balance both
• Prefer interactivity
If you change this option, you must restart the tideway service.

Minimum Windows Proxy version

The minimum version of the Windows proxy that the appliance uses for Windows discovery. You can enter a new minimum Windows proxy version in this field. Ensure that you do not include any white space in the version number. The version number of a Windows proxy corresponds to the version number of BMC Discovery that the Windows proxy was released with (for example, 9.0).
Note: To change the minimum Windows proxy version or release, you must stop scanning.

Enable Automatic Grouping

Automatic grouping is the automatic grouping of hosts into logical groups called Automatic Groups. This is primarily intended to help in baselining. By default it is enabled. Select this option to enable Automatic Grouping. Disabling Automatic Grouping might improve scanning performance.

Scanner File polling interval

Scanner files are used to simulate discovery of inaccessible hosts. Discovery periodically polls for new scanner files. Select the polling interval from the following values in the list: Every minute, Every hour, and Every day.

If you change this option, you must restart the tideway service.
Note: When set to Every day, the polling time is at midnight UTC time. Daylight Saving Time is not considered.

 

Scanning and data processing levels

The Discovery Engine and the Reasoning Engine (collectively the discovery process) cooperate to:

  • Scan selected ranges
  • Process data
  • Create a detailed data model

The data model defines all discovered objects and the relationships between them and is defined in the system taxonomy.

The processing that the discovery process uses to create this complex, detailed, and interrelated data model is considerable. You can control the level of processing used, and consequently the accuracy, complexity, and detail in the data model, giving performance benefits at the cost of model accuracy. You might find that by reducing the level of processing used, you speed the rollout of BMC Discovery throughout your organization.

The following levels are available:

  • Sweep Scan—Performs a sweep scan, trying to determine what is at each endpoint in the scan range. Sweep scan attempts to log in to a device to determine the device type.
  • Full Discovery—Retrieves all the default information for hosts, and complete full inference.

Order of operations

Where selected, these groups of operations are carried out in the following order:

  • Ping hosts before scanning
  • Use TCP ACK "ping" before scanning
  • Use TCP SYN "ping" before scanning
  • TCP ports to use for initial scan
  • UDP ports to use for initial scan
  • Use IP Fingerprinting to Identify OS

TCP and UDP ports to use for initial scan 

The initial port scan is an important part of discovery. If you remove a port from the initial port scan, that port is effectively removed from discovery. For example, if you remove port 22, you will effectively disable SSH access.

The Use Last Login settings override any settings made in ports for use for initial scan. For example, if you disable port 23 using this feature, but a host has previously been discovered using Telnet, this host is still discovered using Telnet, because it is listed as the last login for the host.

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Comments

  1. Lisa Keeler

    The sentence in red is incorrect:


    Scanner File polling interval

    Scanner files are used to simulate discovery of inaccessible hosts. Discovery periodically polls for new scanner files. Select the polling interval from the following values in the list: Every minute, Every hour, and Every day. 
    If you change this option, you must restart the tideway service.
    Note: When set to Every day, the polling time is at midnight UTC time. Daylight Saving Time is not considered.


    It should say:  "If you change this option, you must re-start Discovery.  To re-start Discovery, you click "STOP ALL SCANS", followed by "START ALL SCANS" on the Manage→Discovery page.

    Apr 07, 2018 10:01