snmpgetnext

Request the next value from the SNMP agent

$ snmpgetnext -v [version] -c [community] [ip] [oid]

$ snmpgetnext -v [version] -c [community] -O f [ip] [oid]

$ snmpgetnext [[-h|--help]]

snmpgetnext [APPLICATION OPTIONS] [COMMON OPTIONS] AGENT OID [OID...]

APPLICATION OPTIONS: Options specific to snmpgetnext (though most are common across Net-SNMP tools).
COMMON OPTIONS: Standard Net-SNMP command-line options for authentication, transport, and output.
AGENT: The hostname or IP address of the SNMP agent to query, optionally followed by a colon and port number (e.g., localhost:161).
OID: One or more Object Identifiers (e.g., iso.org.dod.internet.mgmt.mib-2.system.sysDescr.0 or its numerical equivalent 1.3.6.1.2.1.1.1.0). For each OID provided, snmpgetnext will return the next OID and its value.

-v
    Specifies the SNMP protocol version to use. Common values are 1, 2c, or 3.

-c
    Sets the community string for SNMPv1 or SNMPv2c requests (e.g., 'public', 'private').

-r
    Defines the number of retries before the request times out. Default is 5.

-t
    Sets the timeout in seconds before retrying the request. Default is 1.

-O
    Specifies various output formatting options. Examples include q (quiet), f (full OID names), n (numeric OIDs), s (short OID names), x (hex dump), e (enumerate values).

-m
    Specifies a colon-separated list of MIB modules to load. Using ALL loads all known MIBs.

-M
    Specifies a colon-separated list of directories to search for MIB files. Default is usually /usr/share/snmp/mibs.

-Pu
    Forces the use of UDP over IPv6 for communication. Default is UDP over IPv4.

-Pe
    Forces the use of TCP over IPv6 for communication.

-p
    Specifies the destination UDP port for SNMP requests. Default is 161.

-l
    Sets the security level for SNMPv3 requests. Options include noAuthNoPriv, authNoPriv, authPriv.

-u
    Specifies the security name (username) for SNMPv3 authentication.

-a
    Sets the authentication protocol for SNMPv3. Common values are MD5 or SHA.

-A
    Provides the authentication passphrase for SNMPv3.

-x
    Sets the privacy (encryption) protocol for SNMPv3. Common values are DES or AES.

-X
    Provides the privacy passphrase for SNMPv3.

-n
    Specifies the context name for SNMPv3 requests.

-E
    Sets the context engine ID for SNMPv3 requests.

The snmpgetnext command is a powerful utility from the Net-SNMP suite designed to fetch the lexicographically next MIB object from an SNMP-enabled network device (agent). Unlike snmpget, which retrieves the value of a precisely specified Object Identifier (OID), snmpgetnext queries the agent for the OID that immediately follows the one provided in the request. This functionality is crucial for traversing and discovering the structure of an agent's Management Information Base (MIB). It is commonly used as a building block for tools like snmpwalk, which automate the process of retrieving all variables within a specific MIB subtree. It supports various SNMP versions, including SNMPv1, SNMPv2c, and the more secure SNMPv3, allowing for flexible and secure network monitoring and management operations.

Using snmpgetnext requires that an SNMP agent is running and properly configured on the target device, and that network connectivity (including firewall rules) allows SNMP traffic (default UDP port 161). For symbolic OID resolution, ensure the necessary MIB files are installed and accessible to the snmpgetnext command. SNMPv1 and SNMPv2c use clear-text community strings, which pose a security risk on untrusted networks. SNMPv3 offers robust security features including authentication and encryption, which should be preferred for sensitive operations.

A MIB is a hierarchical database that defines the objects managed by an SNMP agent on a network device. OIDs (Object Identifiers) are used to uniquely identify these objects within the MIB tree. snmpgetnext relies on the MIB structure to determine the 'next' object.

OIDs are globally unique identifiers used in SNMP to name objects in a MIB. They are represented as a sequence of numbers separated by dots (e.g., 1.3.6.1.2.1.1.1.0). snmpgetnext operates by finding the OID that immediately follows the provided OID in the MIB's lexicographical order.

SNMPv1: The original version, simple but lacks security.
SNMPv2c: Adds support for 64-bit counters and improved error handling, still uses community strings for authentication.
SNMPv3: Introduces strong authentication (MD5, SHA) and encryption (DES, AES) for secure communication, along with user-based security models.

The Simple Network Management Protocol (SNMP) itself emerged in the late 1980s as a standard for managing devices on IP networks. The snmpgetnext command is part of the Net-SNMP project, an open-source suite of SNMP tools and libraries. Net-SNMP was originally known as UCD-SNMP, developed at the University of California, Davis. Over the years, the project has evolved to support successive versions of the SNMP protocol (v1, v2c, and v3), incorporating new features and security enhancements, making snmpgetnext and related tools indispensable for network monitoring and management.

snmpget(1), snmpwalk(1), snmptable(1), snmpset(1), snmpbulkget(1)