PHP's SNMP extension is an extension that enables PHP to communicate with network devices through the SNMP protocol. Using this extension, you can easily obtain and modify the configuration information of network devices, such as CPU, memory, network interface and other information of routers, switches, etc. You can also perform control operations such as switching device ports.

This article will introduce the basic knowledge of the SNMP protocol, how to install the SNMP extension of PHP, and how to use the SNMP extension in PHP to monitor and control network devices.

1. Overview of SNMP Protocol

SNMP (Simple Network Management Protocol) is a protocol used to manage network devices. It provides a standard method to obtain and modify information about network devices on the network.

The SNMP protocol is divided into three parts: SNMP management system, SNMP agent and SNMP Management Information Base (MIB). The SNMP management system is a system used to manage network devices and communicates with SNMP agents through the SNMP protocol. The SNMP agent is a software that runs on network devices. It collects information that needs to be monitored on the network devices and stores it in the management information base. The management information base is a database used to store information related to network devices, including network device configuration information, performance information, etc.

The SNMP protocol supports message types such as GET, GETNEXT, SET, and TRAP. GET and SET are used to obtain and modify network device information, GETNEXT is used to obtain the value of the next OID, and TRAP is used to report to the management system. Send warning message.

2. Install PHP’s SNMP extension

Before using PHP’s SNMP extension, you need to ensure that the SNMP protocol has been installed on the system. On Linux systems, you can install SNMP with the following command:

sudo apt-get install snmp

On Windows systems, you can download and install SNMP software.

After installing SNMP, you can use the following command to install the SNMP extension of PHP:

pecl install snmp

After the installation is complete, add the following configuration items in the php.ini file:

extension=snmp.so

Restart PHP will complete the installation.

3. Using SNMP extension in PHP

Before using SNMP extension, you need to understand some basic knowledge of SNMP protocol. The SNMP protocol uses OID (Object Identifier) ??to identify various information in network devices. You can use the get and getnext methods of SNMP to obtain the value corresponding to the OID, and use the set method to modify the value corresponding to the OID.

The following are some commonly used SNMP extension functions:

1. snmpget($host, $community, $oid, $timeout, $retries): Get the value corresponding to the OID.

Parameter description:

• $host: Target network device address.
• $community: Community string of SNMP protocol.
• $oid: OID to be obtained.
• $timeout: timeout time.
• $retries: Number of retries.

Sample code:

$value = snmpget("127.0.0.1", "public", "1.3.6.1.2.1.1.1.0", 500000, 3);
echo $value;

2. snmpgetnext($host, $community, $oid, $timeout, $retries): Get the value corresponding to the next OID.

Parameter description is the same as snmpget, sample code:

$value = snmpgetnext("127.0.0.1", "public", "1.3.6.1.2.1.1.1.0", 500000, 3);
echo $value;

3. snmpset($host, $community,$oid, $type, $value, $timeout, $retries ): Set the value corresponding to OID.

Parameter description:

• $host: Target network device address.
• $community: Community string of SNMP protocol.
• $oid: OID to be set.
• $type: The data type corresponding to OID, such as i representing integer type, s representing character type, etc.
• $value: The value to be set.
• $timeout: timeout time.
• $retries: Number of retries.

Sample code:

$status = snmpset("127.0.0.1", "private", "1.3.6.1.2.1.2.2.1.7.1", "i", 1, 500000, 3);
echo ($status === true) ? "Success!" : "Fail!";

Through the above functions, you can easily obtain network device information and perform corresponding control operations.

4. Summary

This article introduces the basic knowledge of the SNMP protocol, the installation method of the SNMP extension of PHP, and how to use the SNMP extension in PHP to monitor and control network devices. Using PHP's SNMP extension can easily obtain and modify network device information, providing a convenient way to manage network devices.

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