Linux

Supportability details

The Linux server pattern can discover only English-based Linux.

Supported Linux operating systems

For IPv4 discovery:

Red Hat
Oracle
Fedora
Debian
SUSE
CentOS
Ubuntu
Alpine Linux (starting from Visibility Content version 6.30.0)*

* Operating System and OS Version only

For IPv6 discovery:

CentOS 7
Ubuntu 20

The following operating systems or devices haven’t been verified for IPv6 discovery:

Red Hat cluster
Oracle Clusterware
Linux Pacemaker cluster
Network storage

Classifier, probes, and pattern


Classifier	Probes	Pattern
Linux (Unix classification)	Horizontal discovery probe: Launches patterns Linux - Installed Software^ Unix - ADM^ Linux - Identity* Linux - CPU* Linux - Distribution* Linux - Find FQDN* Linux - Memory* Linux - Memory Modules* Linux - Network ARP Tables* Linux - Storage* Linux - Amazon EC2* Unix - OS Uptime* UNIX - OS Filesystems* UNIX - Find FQDN* Unix - ADM Enhanced*	Linux Server

*These probes aren't active on the classifier, as Discovery uses patterns by default for these discoveries.

^These probes remain active by default, even when Discovery uses pattern discovery.

To use patterns, verify that the correct pattern is specified in the horizontal pattern probe on the classifier. See Add the Horizontal Pattern probe to a classifier for instructions.

Request new or enhanced Patterns on the ServiceNow® Store

Visit the ServiceNow Store to view all the available updates and for information about submitting requests to the store. For cumulative release notes information for all released apps, see the ServiceNow Store version history release notes.

Requirements for Linux discovery

Before running a discovery, you must verify that all the required configurations are complete.

Verify the plugins installation and activation

Verify the required credentials configuration

Configure the credentials by the required SSH permissions. Discovering sensitive Linux data may require a user with appropriate sudo privileges to run the sudo commands. To configure the required sudo privileges, modify the /etc/sudoers file to include the commands that Discovery needs. For /etc/sudoers line examples for each command, see SSH commands requiring a privileged user during probe-based discovery.

For more information about the commands that require a user with elevated rights, refer to the following documents.

Commands that require root privileges for Discovery, Orchestration, and Integration Hub.
For a list of privileged commands that you need for Discovery and Service Mapping, see Service Mapping commands requiring a privileged user. This list includes commands that require elevated rights to discover and map Unix-based hosts in your organization.
MID Server privileged commands
View Patterns commands through the Discovery Patterns module
Validate commands used in pattern-based discovery

SSH private key credentials are preferable over SSH password credentials for security reasons.

Verify the MID Server configuration

For detailed information, see:

Verify the configuration of the discovery schedule

For information on creating a discovery schedule, see Schedule a horizontal discovery.

Defining IP ranges ensures that only the specified network adapters and their primary IP addresses are used during Linux discovery. You can configure Quick Ranges by entering comma-separated IPv4 address ranges or single IPv6 address.

Alternatively, you can use the network_adapter_exclusion_list property to limit Linux discovery to specific network adapters and their primary IP addresses. For more information, see Omit network adapter secondary IP addresses in Linux discovery.

(Optional) Populate Virtual Machine Object field in Hardware [cmdb_ci_hardware] table

Starting with Discovery and Service Mapping Patterns version 1.30.2, you can improve query performance by populating the Virtual Machine Object field in the Hardware [cmdb_ci_hardware] table. For more information, see Improved query performance with direct field population in CI tables.

Data collected

The Linux classifier triggers probes that perform the discovery. Several probes are launched during the discovery. See the classifier for a list of the trigger probes.

Note:

See the knowledge article KB0687582 for information on model_id and manufacturer.


Label	Table Name	Field Name	Source
Operating System	cmdb_ci_linux_server	os	uname -a
OS Version	cmdb_ci_computer	os_version	uname -a or cat /etc/*release
Short description	cmdb_ci_linux_server	short_description	uname -a
Name	cmdb_ci_linux_server	name	DNS, NBT
Hostname	cmdb_ci_linux_server	host_name	DNS, NBT
DNS domain	cmdb_ci_linux_server	dns_domain	DNS
Start date	cmdb_ci_linux_server	start_date	uptime
Manufacturer	cmdb_ci_computer	manufacturer	dmidecode
Serial number	cmdb_ci_computer	serial_number	dmidecode
CPU type	cmdb_ci_linux_server	cpu_type	/proc/cpuinfo
CPU speed (MHz)	cmdb_ci_linux_server	cpu_speed	/proc/cpuinfo
CPU count	cmdb_ci_linux_server	cpu_count	/proc/cpuinfo
CPU core count	cmdb_ci_computer	cpu_core_count	/proc/cpuinfo
CPU core thread	cmdb_ci_computer	cpu_core_thread	/proc/cpuinfo
CPU manufacturer	cmdb_ci_linux_server	cpu_manufacturer	/proc/cpuinfo
Model number	cmdb_ci_computer	model_number	dmidecode
Model ID	cmdb_ci_computer	model_id	dmidecode
RAM (MB)	cmdb_ci_linux_server	ram	meminfo
Disk space (GB)*	cmdb_ci_linux_server	disk_space	/proc/ide, /proc/scsi, /var/log/dmesg
Type	cmdb_ci_disk	type	/proc/ide, /proc/scsi, /var/log/dmesg
Model ID	cmdb_ci_disk	model_id	/proc/ide, /proc/scsi, /var/log/dmesg
Disk space (GB)	cmdb_ci_disk	disk_space	/proc/ide, /proc/scsi, /var/log/dmesg
Name	cmdb_ci_disk	name	/proc/ide, /proc/scsi, /var/log/dmesg
Name	cmdb_ci_file_system	name	df
Capacity (MB)	cmdb_ci_file_system	capacity	df
Free Space Bytes (MB)	cmdb_ci_file_system	free_space_bytes	df
Mount point	cmdb_ci_file_system	mount_point	df
Name	cmdb_running_process	name	ps
Command	cmdb_running_process	command	ps
Type	cmdb_running_process	type	ps
PID	cmdb_running_process	pid	ps
Parameters	cmdb_running_process	parameters	ps
Name	cmdb_ci_network_adapter	name	ifconfig or ip address show
IP address**	cmdb_ci_network_adapter	ip_address	ifconfig or ip address show
MAC address	cmdb_ci_network_adapter	mac_address	ifconfig or ip address show
Netmask	cmdb_ci_network_adapter	netmask	ifconfig or ip address show
Default gateway	cmdb_ci_hardware	default_gateway	route

* The value in the disk_space field is an aggregation of the total capacity (to include used space) for all non-removable disks, including both directly attached and SAN storage.

Note:

Make sure to define unique serial numbers for the RAMs on the Linux server.

Discovery also identifies and classifies information about Linux KVM. Discovery identifies Linux kernel-based virtual machines (KVM) when the process classifier detects libvirtd running on a Linux server. The classification triggers the creation of a cmdb_ci_kvm record and launches the SSH Command probes to explore the Linux server with virsh, lbvert utility, and virtual machine configuration data.

Discovery creates a [cmdb_ci_kvm_instance] record for each virtual machine on the server, and then matches the [cmdb_ci_kvm_instance] record to a corresponding [cmdb_ci_computer] record using the MAC addresses of installed network adapters.

Table 1. Tables used by Discovery on Linux KVM
Table name	Extends	Description	Source
cmdb_ci_kvm	cmdb_ci_vm	A hypervisor that manages kernel-based virtual machines (KVMs)	Process classifier detects libvirtd running on Linux servers
cmdb_ci_kvm_vm_instance	cmdb_ci_vm_instance	A virtual machine instance on this hypervisor	virsh list-all and dumpxml command
cmdb_ci_kvm_object	cmdb_ci_vm_object	An object connected to a virtual machine instance	<network>, <storage pool>, and <storage volume> elements from the dumpxml command
cmdb_kvm_device	Not applicable	A device connected to a virtual machine instance	<devices> element from the dumpxml command

Table 2. Data collected by Discovery on Linux KVM
Label	Table name	Field name	Source
Linux Host	cmdb_ci_kvm	linux_host	Reference to the cmdb_ci_linux_server that is running this virtual machine
Details	cmdb_ci_kvm	details_xml	dumpxml
Object ID	cmdb_ci_kvm_vm_instance	object_id	virsh dumpxml
State	cmdb_ci_kvm_vm_instance	state	virsh list-all
CPUs	cmdb_ci_kvm_vm_instance	cpus	virsh dumpxml
Memory	cmdb_ci_kvm_vm_instance	memory	virsh dumpxml
Disks	cmdb_ci_kvm_vm_instance	disks	virsh dumpxml
Disks size	cmdb_ci_kvm_vm_instance	disks_size	virsh domblkinfo
Network adapters	cmdb_ci_kvm_vm_instance	nics	virsh dumpxml
Name	cmdb_ci_kvm_vm_instance	name	virsh dumpxml
Short description	cmdb_ci_kvm_vm_instance	short_description	virsh desc
Details	cmdb_ci_kvm_object	details_xml	XML element from dumpxml
KVM instance	cmdb_kvm_device	kvm_instance	Reference to cmdb_ci_kvm_instance
Device	cmdb_kvm_device	device	disk, controller, interface, and so on
Type	cmdb_kvm_device	type	depends on the device
Details	cmdb_kvm_device	details_xml	XML element from dumpxml

Table 3. Data collected by Discovery on KVM Relationship
Relationship	Parent table	Child table
Registered On::Has Registered	KVM [cmdb_ci_kvm]	KVM Virtual Machine instance [cmdb_ci_kvm_vm_instance]
Provided By::Provides	KVM [cmdb_ci_kvm]	Network [cmdb_ci_kvm_network]
Defines resource for::Gets resources from	KVM [cmdb_ci_kvm]	Storage Pool [cmdb_ci_kvm_storage_pool]
Connected By::Connects	KVM Virtual Machine instance [cmdb_ci_kvm_vm_instance]	Network [cmdb_ci_kvm_network]
Instantiated By::Instantiates	KVM Virtual Machine instance [cmdb_ci_kvm_vm_instance]	Computer [cmdb_ci_computer]
Virtualized By::Virtualizes	Computer [cmdb_ci_computer]	KVM [cmdb_ci_kvm]
Provides storage for::Stored on	Storage Pool [cmdb_ci_kvm_storage_pool]	KVM Virtual Machine instance [cmdb_ci_kvm_vm_instance]