SNMP is a communications protocol that allows remote monitoring and remote management of devices running on an Ethernet network.
Remote management requires:
1. A communication protocol (SNMP protocol);
2. Management Information Bases, MIB.
3. An SNMP agent.
4. An SNMP Manager.
The SNMP protocol runs at the application level of the TCP/IP protocols stack and is used by managers and agents to exchange messages.
An SNMP manager is a software application through which a user can send requests to an SNMP agent.
An SNMP agent is a software application that runs on a specific device and monitors certain aspects of it.
How to represent data in the SNMP context:
-The monitored items are defined in a MIB Objects file.
-A MIB file is a text file where the monitored objects are defined using ASN.1 (Abstract Syntax Notation 1)
-ASN.1 is a formal language used to define its data and properties.
A manager communicates with an SNMP agent via the UDP protocol.
Object monitored:
– Each object has a unique identifier (OID).
– An OID is declared in a MIB file.
– An OID can be represented either as a string of integers separated by a point or as a string of point-separated names.
When a manager requests information about an object, it sends the OID agent to the object.
How to Organize Objects:
– Orders are organized in the shape of a tree. Each OID is a node in the tree.
– Equipment manufacturers will add their own branch to specific devices.
A manager communicates with an SNMP agent via the UDP protocol.
SNMP operations:
1. Get-request. Manager interrogates the agent about the value of a particular object
2. Get-next-request. Manager requests the value of the object following the object specified in the request.
3. Set-request. Manager requests the value of a particular object to be changed.
4. Get-response. An SNMP agent response as a result of a get-request, get-next-requests or set-request query.
5. Trap. A warning sent by the agent to the manager when an unexpected event occurs related to the monitored device.
SNMP versions
There are three versions of SNMP:
1. SNMPv1 (1990)
2. NMPv2c (1996) • Defines new SNMP operations.
3. SNMPv3 (2002) • Improves security issues.
SNMP security
–SNMPv1 uses the notion of community to authenticate between a manager and an agent.
–NMPv3:
1. Ensure that a data packet has not been modified and it has integrity.
2. Ensure that a message comes from a valid authentication source.
3. Guarantees that a message is not accessible to an unauthorized source.
At the beginning of the ARPANET development, if the delay to a particular host system was very high, the person who detected the problem executed the Ping program to receive a package from the destination. By analyzing the time stamps of the returned package header, the location of the problem could be determined, and steps were taken to resolve it. Also, the number of routers was so small that it was possible to check everyone to find out which of them had problems.
When ARPANET became the Internet, this international network, with multiple spine columns and a lot of operators, the solution ceased to be adequate, so better tools for network management were needed. Two of the first attempts were defined in RFC 1028 and RFC 1067, but their lives were short. In May 1990 RFC 1157 was published, defining version l of Simple Network Management Protocol (SNMP). Together with an accompanying document (RFC 1155) on management information, SNMP provides a systematic way to monitor and manage a computer network. This structure and protocol have been widely deployed in commercial applications and have become “de facto” standards for network management.
Automated network management
If you happen to have an extensive network with hundreds or thousands of nodes, it’s hard to manage it without a lot of staff member to monitor each computer.
SNMP, which is most commonly used in local area networks (LANs) and allows you to monitor network nodes from a host.
You can easily monitor network devices such as workstations, servers, routers, printers, bridges, and hubs, as well as services such as Dynamic Host Configuration Protocol (DHCP).
You can use SNMP management software to monitor any network device located in the network where you install the SNMP software agent.