How to use the command snmpwalk (with examples)

Snmpwalk is a command-line tool that is used for querying system information of a remote host using the SNMP (Simple Network Management Protocol). It allows users to retrieve information from network devices and monitor the performance and health of these devices. Snmpwalk supports different versions of SNMP, including SNMPv1, SNMPv2, and SNMPv3, and provides various options to configure authentication, encryption, and community strings.

Use case 1: Query the system information of a remote host using SNMPv1 and a community string

Code:

snmpwalk -v1 -c community ip

Motivation: This use case is suitable if you are targeting a remote host that supports SNMPv1 and requires a community string for authentication. It enables you to retrieve system information, such as the hostname, interfaces, and network statistics.

Explanation:

• -v1: Sets the SNMP version to SNMPv1.
• -c community: Specifies the community string to authenticate with the remote host.
• ip: The IP address or hostname of the remote host.

Example output:

iso.2.1.1.0 = STRING: "example-host"
iso.2.1.2.0 = STRING: "1.3.6.1.4.1.12345"
iso.2.2.1.1.1.1 = STRING: "eth0"
iso.2.2.1.1.1.2 = STRING: "eth1"
...

Use case 2: Query system information on a remote host by OID using SNMPv2 on a specified port

Code:

snmpwalk -v2c -c community ip:port oid

Motivation: This use case is useful if you want to retrieve system information using SNMPv2 and need to specify a non-standard SNMP port to connect to the remote host.

Explanation:

• -v2c: Sets the SNMP version to SNMPv2.
• -c community: Specifies the community string to authenticate with the remote host.
• ip:port: The IP address or hostname of the remote host followed by the SNMP port number.
• oid: The Object Identifier (OID) to query.

Example output:

iso.3.6.1.2.1.1.1.0 = STRING: "Example System"
iso.3.6.1.2.1.1.2.0 = OID: iso.3.6.1.4.1.12345
iso.3.6.1.2.1.2.2.1.1.1 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.1.2 = INTEGER: 2
...

Use case 3: Query system information on a remote host by OID using SNMPv3 and authentication without encryption

Code:

snmpwalk -v3 -l authNoPriv -u username -a MD5|SHA -A passphrase ip oid

Motivation: This use case is appropriate when you require SNMPv3 with authentication but without encryption to query the system information of a remote host. It allows you to specify the authentication protocol (MD5 or SHA) and passphrase for authentication.

Explanation:

• -v3: Sets the SNMP version to SNMPv3.
• -l authNoPriv: Specifies the SNMPv3 security level to use authentication without encryption.
• -u username: Specifies the SNMP username for authentication.
• -a MD5|SHA: Specifies the authentication protocol to use, either MD5 or SHA.
• -A passphrase: Specifies the authentication passphrase.
• ip: The IP address or hostname of the remote host.
• oid: The Object Identifier (OID) to query.

Example output:

iso.1.3.6.1.2.1.1.1.0 = STRING: "Example System"
iso.1.3.6.1.2.1.1.2.0 = OID: iso.3.6.1.4.1.12345
iso.1.3.6.1.2.1.2.2.1.1.1 = INTEGER: 1
iso.1.3.6.1.2.1.2.2.1.1.2 = INTEGER: 2
...

Use case 4: Query system information on a remote host by OID using SNMPv3, authentication, and encryption

Code:

snmpwalk -v3 -l authPriv -u username -a MD5|SHA -A auth_passphrase -x DES|AES -X enc_passphrase ip oid

Motivation: This use case is suitable when you need both authentication and encryption to query system information using SNMPv3. It allows you to configure the authentication protocol (MD5 or SHA), authentication passphrase, encryption protocol (DES or AES), and encryption passphrase.

Explanation:

• -v3: Sets the SNMP version to SNMPv3.
• -l authPriv: Specifies the SNMPv3 security level to use authentication and encryption.
• -u username: Specifies the SNMP username for authentication.
• -a MD5|SHA: Specifies the authentication protocol to use, either MD5 or SHA.
• -A auth_passphrase: Specifies the authentication passphrase.
• -x DES|AES: Specifies the encryption protocol to use, either DES or AES.
• -X enc_passphrase: Specifies the encryption passphrase.
• ip: The IP address or hostname of the remote host.
• oid: The Object Identifier (OID) to query.

Example output:

iso.2.3.4.5.6 = STRING: "Example System"
iso.2.3.4.5.7 = OID: iso.3.6.1.4.1.12345
iso.2.3.4.5.8.1 = INTEGER: 1
iso.2.3.4.5.8.2 = INTEGER: 2
...

Use case 5: Query system information on a remote host by OID using SNMPv3 without authentication or encryption

Code:

snmpwalk -v3 -l noAuthNoPriv -u username ip oid

Motivation: This use case is useful if you want to query system information using SNMPv3 without any authentication or encryption. It allows you to specify the SNMP username without requiring any authentication or encryption keys.

Explanation:

• -v3: Sets the SNMP version to SNMPv3.
• -l noAuthNoPriv: Specifies the SNMPv3 security level to use no authentication or encryption.
• -u username: Specifies the SNMP username.
• ip: The IP address or hostname of the remote host.
• oid: The Object Identifier (OID) to query.

Example output:

iso.3.4.5.6.7 = STRING: "Example System"
iso.3.4.5.6.8 = OID: iso.3.6.1.4.1.12345
iso.3.4.5.6.9.1 = INTEGER: 1
iso.3.4.5.6.9.2 = INTEGER: 2
...

Conclusion:

Snmpwalk is a versatile command-line tool for querying system information using SNMP. It supports different SNMP versions and provides options for configuration, such as authentication, encryption, community strings, and OIDs. By understanding these use cases and their corresponding commands, you can retrieve the desired system information from remote hosts efficiently.