The Simple Network Management Protocol (SNMP) is a networking protocol used in Internet Protocol networks to manage and monitor network-connected devices. The SNMP protocol is embedded in various devices such as routers, switches, servers, firewalls, etc., that can be accessed via their IP address. SNMP provides a standard mechanism for network devices to communicate management information within single and multi-vendor LAN or WAN environments. In the OSI model framework, it is an application layer protocol.
There are three versions of SNMP: SNMPv1, SNMPv2c, and SNMPv3. The DSM supports SNMP version 1 or 2.
Components of SNMP
The following are key components of SNMP through with it performs its basic tasks:
An SNMP agent is a software process that responds to SNMP queries to provide network node status and statistics. They are located locally and are linked to SNMP network devices from which they collect, store, and transmit monitoring data. When data is queried, it is sent to the designated SNMP manager.
It is also referred to as the SNMP server and is responsible for communicating with the SNMP agent-implemented network devices. The manager queries the agents, gets responses from them, sets variables, and acknowledges events from them.
Management information base (MIB)
This exists in the form of a text file (with extension .mib) and describes all data objects used by a specific device that can be queried or controlled using SNMP. Various managed objects within the MIB can be identified using Object Identifiers (Object ID or OID).
Object Identifier (OID)
There are two types of OIDs: Scalar and tabular. These are typically represented as a dotted list of integers. MIBs hierarchically organize every OID, which can be represented in a tree structure with individual variable identifiers for each OID.
SNMP in Vormetric DSM
The Vormetric DSM can be enabled as an SNMP agent and then monitored by SNMP servers using the available MIB objects. When the DSM receives an SNMP GET request (sent to port 7025 or 161) from an SNMP server, the DSM locates the OID entry in the MIB and returns its value to the SNMP server.
SNMP is enabled via the System > SNMP page on the Configuration tab. If the SNMP Access Control List (ACL) is empty, SNMP requests from any IP address will be acknowledged. If the
SNMP ACL is defined to allow only certain IP addresses or IP address blocks to go through; the DSM will only acknowledge requests from IP addresses specified in the SNMP ACL.
The community string is typically set to a factory default value of “public”. This string must be the same for all devices in the same group for SNMP monitoring to function. For security reasons, it is advised to change the community string from “public” to a custom value.
SNMP traps are currently not supported and cannot be configured on the DSM.
The following table represents Vormetric-specific OIDs that can be queried by an SNMP server and are present under the Vormetric MIB tab. These OIDs cannot be manually changed; however, those (sysContact and sysLocation) available under System Group MIB can be customized.
Returns the version details of the DSM
Returns the fingerprint of the current DSM deployment
Returns the current date and time on the DSM
Returns the agent type (FS, or Key agent), the license installation state (true or false) of each agent type, and, for each installed license, the license expiration date
Returns the name of each node in a DSM HA cluster configuration.
Returns disk usage information for each file system mounted on the DSM.
Return DSMs process, memory, paging, I/O, and CPU usage information
Encryption Consulting recently developed a shell script for one of its customers leveraging the SNMP functionality of Vormetric DSM to automate the process of obtaining insights on the parameters mentioned above. It can be remotely executed from a Linux or Unix host and includes all the commands required to query the DSM using the OIDs provided.
Configuring SNMP in Vormetric DSM can help in its monitoring through an SNMP server. The available OIDs can enable the server to gather information about the DSM with regard to contact information, physical location, version number, fingerprint, server time, license and HA configuration, and disk and system usage information. However, the SNMP functionality must be enabled only with proper security measures, such as by using SNMP ACL to restrict access to the service