 Simple Network Management Protocol (SNMP) is a
popular protocol for network management.
 It is used for collecting info...
 Large networks with hundreds or thousands of nodes are
difficult to manage without a large staff to monitor every
comput...
The SNMP architecture is composed of three major elements:
 Managers (software) are responsible for communicating
with (a...
 Before we go any further, we need to introduce the
concept of Object Identifiers or OID’s. Each MIB object
definition ha...
 “get” commands are sent by a Manager to an Agent to
request data values defined by a MIB. The Agent will
respond with th...
Standards Topics can generally be categorized into:
 Messaging protocols between Managers and
Agents (which encompasses s...
Three messaging protocols exist:
 SNMPv1 was the first protocol introduced, and it is still
widely used. It implements
“g...
 SNMPv2 usually refers to SNMPv2c (other v2’s were
proposed, but only v2c survives today).
It introduced the ability to t...
 SNMPv3 is the most recent introduction, and it is a major step
forward in improving security. Security enhancements incl...
 VACM (View Access Control Model): Agents can now
be configured to control who can access which MIB
Objects under agent m...
 MIBs are written in either of the following two syntax
standards:
SMIv1 is the earliest version and was introduced along...
 MIv2 was introduced along with SNMPv2c. Major
enhancements include:
Introduction of new data base types, including the
“...
Depending on the origin (author) of a MIB, we can
categorize MIBs into either:
 Enterprise MIBs
 Or Standard MIBs
Enterp...
 Standard MIBs are authored by persons
associated with the IETF. For example, a standard
Printer MIB exists, and printer ...
Strengths
 Many standard MIBs available
 Widespread popularity
 Agents have low impact on monitored system
resources
 ...
Weaknesses
 Not bandwidth efficient
 Not as comprehensive as some other protocols
 Complicated message encoding rules
...
Here are some typical uses of SNMP:
 Detecting device faults, or recovery from faults
 Monitoring device performance
 C...
Books
 Understanding SNMP MIBs by David Perkins &
Evan McGinnis. Prentice Hall, 1997
 SNMP, SNMPv2, SNMPv3, and RMON 1 a...
Thank You
SNMP (MV ASHOK)
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SNMP (MV ASHOK)

  1. 1.  Simple Network Management Protocol (SNMP) is a popular protocol for network management.  It is used for collecting information from, and configuring, network devices, such as servers, printers, hubs, switches, and routers on an Internet Protocol (IP) network.  Simple Network Management Protocol (SNMP) is a widely used protocol designed to facilitate the management of
  2. 2.  Large networks with hundreds or thousands of nodes are difficult to manage without a large staff to monitor every computer.  SNMP, which is widely used in local area networks (LANs), lets you monitor network nodes from a management host.  You can monitor network devices such as servers, workstations, printers, routers, bridges, and hubs, as well as services such as Dynamic Host Configuration Protocol (DHCP) or Windows Internet Name Service (WINS).  Use SNMP management software to monitor any network device on which you install SNMP agent software.
  3. 3. The SNMP architecture is composed of three major elements:  Managers (software) are responsible for communicating with (and managing) network devices that implement SNMP Agents (also software).  Agents reside in devices such as workstations, switches, routers, microwave radios, printers, and provide information to Managers.  MIBs (Management Information Base) describe data objects to be managed by an Agent within a device. MIBs are actually just text files, and values of MIB data objects are the topic of conversation between Managers and Agents.
  4. 4.  Before we go any further, we need to introduce the concept of Object Identifiers or OID’s. Each MIB object definition has a unique OID, which is a dotted listed of integers.  When Managers and Agents communicate, they refer to MIB data objects using OID’s.  An OID sent with a corresponding value {OID,Value} is referred to as “binding”.  Managers can be viewed as Clients; and Agents, as Servers. The operations between Managers and Agents are quite simple:
  5. 5.  “get” commands are sent by a Manager to an Agent to request data values defined by a MIB. The Agent will respond with the requested values. Closely related requests are “getnext” and “getbulk”.  A Manager can also send “set” commands to an Agent. If the MIB defines a data object as read-write, then the Agent will accept the data value sent with the “set” command and process it appropriately (store it or execute appropriate action).  Agents will send unsolicited “traps” (alarms) to Managers to alert them to important events.
  6. 6. Standards Topics can generally be categorized into:  Messaging protocols between Managers and Agents (which encompasses security issues)  MIB syntax standards  “Standard MIB” definitions
  7. 7. Three messaging protocols exist:  SNMPv1 was the first protocol introduced, and it is still widely used. It implements “get”, “getnext”, “getresponse”, “set”, and “trap” operations. Security for SNMPv1 is based on a “community string” that is transmitted with each message. The community string acts as a password. If the Manger includes the correct password in a request to an agent, the agent will send a response. The community string is not encrypted and thus the security it provides is quite weak.
  8. 8.  SNMPv2 usually refers to SNMPv2c (other v2’s were proposed, but only v2c survives today). It introduced the ability to transmit SMIv2 MIB-definitions of type “Counter64”. SNMPv2c also provides expanded messaging operations: “getbulk”, “inform”, “report”, and a new “v2trap” operation (same functionality as the v1 “trap”). It also introduced enhanced error responses by Agents. SNMPv2c utilizes the same community string security as SNMPv1.
  9. 9.  SNMPv3 is the most recent introduction, and it is a major step forward in improving security. Security enhancements include: User Authentication: Verification of the identify of the SNMP Entity (Manager or Agent) sending the request. Managers and Agents share knowledge of valid users, and there is a shared secret key defined for each user. When an Entity sends an SNMPv3 message, the secret key is used to create a hash of the message, and this hashed value is included with the message. If the receiving Entity can recreate this hash, then the message is said to be “authenticated” as from a valid user. Encryption: Message payload can be optionally encrypted based on a second shared key.
  10. 10.  VACM (View Access Control Model): Agents can now be configured to control who can access which MIB Objects under agent management. For example, User = “Operations Supervisor” can access critical read- write control data, while User = “Plant Monitor” can access only read-only status data. Message Timeless Checks ensure that messages are not delayed or replayed.
  11. 11.  MIBs are written in either of the following two syntax standards: SMIv1 is the earliest version and was introduced along with SNMPv1. SMIv1 MIBs are very functional and very common. Data defined by SMIv1 MIB Objects can be transmitted between Managers and Agents by any of the three messaging protocols, viz., SNMPv1, SNMPv2c, or SNMPv3.
  12. 12.  MIv2 was introduced along with SNMPv2c. Major enhancements include: Introduction of new data base types, including the “Counter64” data type. Although derived data types could be defined in SMIv1, SMIv2 formalizes this syntax and also defines some “Standard Textual Conventions” such as “Display String”.
  13. 13. Depending on the origin (author) of a MIB, we can categorize MIBs into either:  Enterprise MIBs  Or Standard MIBs Enterprise MIBs are authored by non-standards- committee organizations, e.g., Cisco or HP. All such organizations must apply for a unique “Enterprise ID” issued by the Internet Assigned Number Authority (IANA). Enterprise MIBs are then organized under these unique ID’s.
  14. 14.  Standard MIBs are authored by persons associated with the IETF. For example, a standard Printer MIB exists, and printer manufacturers commonly implement an Agent to support this MIB in addition to their own Enterprise MIBs.
  15. 15. Strengths  Many standard MIBs available  Widespread popularity  Agents have low impact on monitored system resources  Well suited to monitoring  Many products available
  16. 16. Weaknesses  Not bandwidth efficient  Not as comprehensive as some other protocols  Complicated message encoding rules  Security has been on on-going concern. SNMPv3 was developed in response to this issue.  UDP, or other connectionless, protocol is used, which creates issues regarding verification of operations: Trap- Send verification (did it really reach the Manager?); Verification (success) of any “set” operation to an Agent. However, cleverly designed MIBs and Manager logic can overcome these problems.
  17. 17. Here are some typical uses of SNMP:  Detecting device faults, or recovery from faults  Monitoring device performance  Collecting long term performance data  Remote configuration of devices  Remote device control
  18. 18. Books  Understanding SNMP MIBs by David Perkins & Evan McGinnis. Prentice Hall, 1997  SNMP, SNMPv2, SNMPv3, and RMON 1 and 2 by William Stallings. Addison-Wesley, 1996  Essential SNMP by Mauro & Schmidt. O’Reilly, 2005  A Practical Guide to SNMPv3 and Network Management by David Zeltserman. Prentice-Hall PTR, 1999
  19. 19. Thank You

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