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Introduction to SNMP. Yen-Cheng Chen http://www.im.tj.mcu.edu.tw/~ycchen/ [email protected] Contents. 1. Basic Concepts 2. Management Information Base 3. Simple Network Management Protocol 4. SNMP Application Examples 5. Reference Appendix: ASN.1 Concept. FDDI. PC. PC. PC. UNIX.

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Introduction to snmp

Introduction to SNMP

Yen-Cheng Chen

http://www.im.tj.mcu.edu.tw/~ycchen/

[email protected]


Contents

Contents

1. Basic Concepts

2. Management Information Base

3. Simple Network Management Protocol

4. SNMP Application Examples

5. Reference

Appendix: ASN.1 Concept


1 basic concepts

FDDI

....

....

....

PC

PC

PC

UNIX

UNIX

UNIX

1. Basic Concepts

Management

Station

NM

...

RMON

Device

Notification

Polling

Firewall

/ Router

...

Internet


Introduction to snmp

網路管理標準化

  • 如果每個廠商的網路設備均提供一套獨特專屬(Proprietary)的網管方法與介面,網路管理工作將很難執行。

  • 網路管理標準化

    • 每個網路設備必須提供一致的網路管理介面(亦即相同的網路管理通信協定)。


Introduction to snmp

網路管理相關標準

  • Internet

    • SNMPv1, SNMPv2, SNMPv3

  • ISO/ITU-T X.700 Series:

    • CMIP/S (Common Management Information Protocol / Service)

  • ITU-T M.3000 Series:

    • TMN (Telecommunication Management Networks)


Snmp concepts

SNMP Concepts

  • SNMP:

    • Simple Network Management Protocol

    • De facto standards of network management for TCP/IP networks (Internet)

    • IAB recommends all IP & TCP implementations should be network manageable.

    • That is, all TCP/IP network devices should support SNMP.

IAB: Internet Activities Board


Snmp architectural model

SNMP Architectural Model

  • Key Components

    • One or more Management Stations

      • Perform management applications, i.e, Monitor & Control.

    • Multiple Network Elements

      • hosts, routers, gateways, ..., which each contain an Agent.

    • Network Management Protocol

      • Exchange network management information.


Snmp architectural model cont

SNMP

SNMP

SNMP

UDP

UDP

UDP

IP

IP

IP

網路介面

網路介面

網路介面

Network

SNMP Architectural Model (cont.)

Network Elements (NEs)

Management

Station

Host

Router

Manager

Agent

Agent

Network

Management

Protocol

. . .

SNMP


Management components

Management Components

  • Manager

  • Agent

  • Network Management Protocol

  • Management Information Base (MIB)


Management components1

Management Components

  • Management Station (Manager)

    • Network management applications.

    • Provide an interface which the human network manager can monitor and control the network.

  • Agent

    • Network devices should be equipped with agent software so that they can be managed from a management station.

    • Responds to requests for information from managers.

    • Responds to requests for actions from managers.

    • May asynchronously provide managers with important but unsolicited information.


Management components cont

Management Components (cont.)

  • Network Management Protocol

    • Communication protocol between managers and agents

    • NM protocol provides a standard way to exchange management information between managers and agents.

  • Management Information Base (MIB)

    • A collection of Managed Objects.

    • The resources to be managed are represented as objects, called Managed Objects (MOs).


Management information base mib

Management Information Base (MIB)

Managed Resources

  • Each resource to be managed is represented by an object, called managed object (MO).

  • The MIB is a structured collection of MOs.

  • Essentially, each MO is a data variable.

  • Each agent in an NE maintains an MIB.

  • Monitor: by reading the values of MOs in the MIB.

  • Control: by modifying the values of MOs in the MIB.

MIB

Agent

SNMP

UDP

IP

網路介面

NE: Network Element


Snmp services

Get, Set, GetNext Request

Get Response

Trap

SNMP Services

  • Four Services

    • Get, Set, GetNext, Trap

  • Five SNMP PDUs

    • GetRequest, SetRequest, GetNextRequest, GetResponse, Trap

Manager

Agent(s)

PDU: Protocol Data Unit


Snmp services1

Get Request

Set Request

Get Response

Get Response

Manager

Manager

Manager

Manager

Agent

Agent

Agent

Agent

GetNext Request

Get Response

Trap Request

SNMP Services

Get

GetNext

Set

Trap


Snmp services cont

SNMP Services (cont.)

  • Get Request:

    • Retrieve the values of objects in the MIB of an agent.

  • Get-Next Request:

    • Retrieve the values of the next objects in the MIB of an agent.

  • Set Request:

    • Update the values of objects in the MIB of an agent.

  • Trap Request

    • Report extraordinary events to the manager.


Get next request

MIB Tree :

4

5

6

:Non-Leaf Object

1

2

3

:Leaf Object

Get-Next Request

In SNMP,

Only leaf objects have

values.


Default udp ports for snmp

Any

161

Any

162

Default UDP Ports for SNMP

Management

Station

Network Elements (NEs)

Manager

Agent

SNMP

SNMP

UDP

UDP

IP

IP

網路介面

網路介面


Snmp standards

SNMP Standards

  • SNMP Protocol (Std 15)

    • RFC1157: Simple Network Management Protocol.

  • Structure of Management Information (SMI) (Std 16)

    • RFC1155: Structure and Identification of Management Information for TCP/IP-based Internets.

    • RFC1212: Concise MIB Definitions.

  • MIB-II (Std 17)

    • RFC1213: Management Information Base for Network Management of TCP/IP-based Internets: MIB-II.

http://www.isi.edu/rfc-editor/rfc.html


2 management information base

2. Management Information Base

  • Structure of Management Information (SMI)

    • Set of rules on how managed objects should be defined.

    • Objects are defined using Abstract Syntax Notation One ASN.1 (ITU-T X.208 / ISO 8824)

  • MIB

    • The collection of all defined objects

    • Contains hierarchically organized variables corresponding to managed objects.

    • MIB-II, RMON MIB, Bridge MIB, Repeater MIB, X.25 MIB, FDDI MIB, Token Ring MIB, ...


Object identifier

Object Identifier

  • Object Identifier (OID):

    • Global identifier for a particular object type.

    • An OID consists of a sequence of integers, which specify the position of the object in the global object identifier tree.

root

0

2

1

iso

ccitt

joint-iso-ccitt

3

0

2

1

1.3.6.1.2.1

org

reg

authority

std

member

body

6

dod

1

1.3.6.1.2.1.2

1.3.6.1.4.1

internet

1

4

3

2

mgmt

directory

private

experimental

1

1

MIB II

MIB II

enterprises

enterprises

interface

system

1

interface

2

at

3

Trans.

10

SNMP

11

IP

4

ICMP

5

TCP

6

UDP

7

EGP

8


Private mib registration

Private MIB Registration

  • Companies can register their private MIB extensions in the global MIB tree by contacting the Internet Assigned Numbers Authority (IANA).

    • http://www.iana.org/

  • Currently assigned enterprise subtrees

ftp://ftp.isi.edu/in-notes/iana/assignments/enterprise-numbers


Smi rfc1155

SMI (RFC1155)

RFC1155-SMI DEFINITIONS ::=

BEGIN

EXPORTS -- EVERYTHING

internet, directory, mgmt, experimental, private,

enterprises, OBJECT-TYPE, ObjectName,

ObjectSyntax, SimpleSyntax,

ApplicationSyntax, NetworkAddress, IpAddress,

Counter, Gauge, TimeTicks, Opaque;

internet OBJECT IDENTIFIER ::= { iso org(3) dod(6) 1 }

directory OBJECT IDENTIFIER ::= { internet 1 }

mgmt OBJECT IDENTIFIER ::= { internet 2 }

experimental OBJECT IDENTIFIER ::= { internet 3 }

private OBJECT IDENTIFIER ::= { internet 4 }

enterprises OBJECT IDENTIFIER ::= { private 1 }


Smi cont

SMI (cont.)

ASN.1 Macro

OBJECT-TYPE MACRO ::=

BEGIN

TYPE NOTATION ::=

"SYNTAX" type (TYPE ObjectSyntax)

"ACCESS" Access

"STATUS" Status

VALUE NOTATION ::= value (VALUE ObjectName)

Access ::= "read-only"

| "read-write"

| "write-only"

| "not-accessible"

Status ::= "mandatory"

| "optional"

| "obsolete"

END

ObjectName ::= OBJECT IDENTIFIER


Object type example

OBJECT-TYPE Example

sysDesc OBJECT-TYPE

SYNTAX DisplayString (SIZE (0..255))

ACCESS read-only

STATUS mandary

::= { system 1}


Introduction to snmp

SMI (cont.)

NetworkAddress ::=

CHOICE {

internetIpAddress}

IpAddress ::=

[APPLICATION 0]

IMPLICIT OCTET STRING (SIZE (4))

Counter ::=

[APPLICATION 1]

IMPLICIT INTEGER (0..4294967295)

Gauge ::=

[APPLICATION 2]

IMPLICIT INTEGER (0..4294967295)

TimeTicks ::=

[APPLICATION 3]

IMPLICIT INTEGER (0..4294967295)

Opaque ::=

[APPLICATION 4]

IMPLICIT OCTET STRING

END

ObjectName ::= OBJECT IDENTIFIER

ObjectSyntax ::=

CHOICE {

simple SimpleSyntax,

application-wide

ApplicationSyntax}

SimpleSyntax ::=

CHOICE {

number INTEGER,

stringOCTET STRING,

objectOBJECT IDENTIFIER,

emptyNULL} }

ApplicationSyntax ::=

CHOICE {

addressNetworkAddress,

counterCounter,

gauge Gauge,

ticksTimeTicks,

arbitraryOpaque

}


Object syntax summary

Simple Syntax

Integer

Octet String

Object Identifier

Null

Application Syntax

Network Address

Counter

Gauge

Time Ticks

Opaque

Object Syntax Summary


Concise mib definition rfc 1212

Concise MIB Definition (RFC 1212)

DescrPart ::=

"DESCRIPTION" value (description DisplayString)

| empty

ReferPart ::=

"REFERENCE" value (reference DisplayString)

| empty

IndexPart ::=

"INDEX" "{" IndexTypes "}" | empty

IndexTypes ::=

IndexType | IndexTypes "," IndexType

IndexType ::=

value (indexobject ObjectName) | type (indextype)

DefValPart ::=

"DEFVAL" "{" value (defvalue ObjectSyntax) "}"

| empty

END

OBJECT-TYPE MACRO ::=

BEGIN

TYPE NOTATION ::=

"SYNTAX" type(ObjectSyntax)

"ACCESS" Access

"STATUS" Status

DescrPart

ReferPart

IndexPart

DefValPart

VALUE NOTATION ::=

value (VALUE ObjectName)


Examples mib ii rfc 1213

mib-2 OBJECT IDENTIFIER ::= { mgmt 1 }

system OBJECT IDENTIFIER ::= { mib-2 1 }

interfaces OBJECT IDENTIFIER ::= { mib-2 2 }

at OBJECT IDENTIFIER ::= { mib-2 3 }

ip OBJECT IDENTIFIER ::= { mib-2 4 }

icmp OBJECT IDENTIFIER ::= { mib-2 5 }

tcp OBJECT IDENTIFIER ::= { mib-2 6 }

udp OBJECT IDENTIFIER ::= { mib-2 7 }

egp OBJECT IDENTIFIER ::= { mib-2 8 }

-- cmot OBJECT IDENTIFIER ::= { mib-2 9 }

transmission OBJECT IDENTIFIER ::= { mib-2 10 }

snmp OBJECT IDENTIFIER ::= { mib-2 11 }

Examples: MIB II (RFC 1213)

ifTable OBJECT-TYPE

SYNTAX SEQUENCE OF IfEntry

ACCESS not-accessible

STATUS mandatory

DESCRIPTION

"A list of interface entries.

The number of entries is given

by the value of ifNumber."

::= { interfaces 2 }

ifEntry OBJECT-TYPE

SYNTAX IfEntry

ACCESS not-accessible

STATUS mandatory

DESCRIPTION

"An interface entry containing objects

at the subnetwork layer and below for

a particular interface."

INDEX { ifIndex }

::= { ifTable 1 }


Identification of managed objects

Identification of Managed Objects

  • Use Object Identifier (OID)

  • OID = Object Type OID . Instance Identifier

  • Object Type OID:

    • Each Object type has a unique OID

  • Instance Identifier:

    • Identify instances of object type

  • E.g.mib-2.interface.ifTable.ifEntry.ifDescr.2


Two kinds of managed objects

Two Kinds of Managed Objects

  • Type-Specific Objects:

    • sysDescr OBJECT-TYPE

      SYNTAX DisplayString (SIZE(0..255))

      ::= {system 1}

    • OID: mib-2.system.1.0

  • Columnar Objects

    • OID:

mib-2.interface.ifTable.ifEntry.ifDescr.2

mib-2.interface.ifTable.ifEntry.ifDescr.6

mib-2.interface.ifTable.ifEntry.ifType.2

mib-2.interface.ifTable.ifEntry.ifType.6


Columnar objects

Columnar Objects

IfEntry ::= SEQUENCE {

ifIndexINTEGER,

ifDescrDisplayString,

ifTypeINTEGER,

}

ifTable OBJECT-TYPE

SYNTAX SEQUENCE OF IfEntry

::= { interface 2 }

ifEntry OBJECT-TYPE

SYNTAX IfEntry

INDEX {ifIndex }

::= { ifTable 1}

ifDescr OBJECT-TYPE

SYNTAX DisplayString (SIZE(0..255))

ACCESS read-only

STATUS madatory

...

::= {ifEntry 2}


Columnar objects1

Columnar Objects

.ifTable.ifEntry.1 (1.3.6.1.2.1.2.2.1.1) .ifTable.ifEntry.2 (1.3.6.1.2.1.2.2.1.2)

.ifTable.ifEntry.3 (1.3.6.1.2.1.2.2.1.3)

ifIndex ifDescr ifType . . .

1 le0 6 . . .

6 llc0 1 . . .

7 lo0 24 . . .

9 le1 6 . . .

1.3.6.1.2.1.2.2.1.2.6

1.3.6.1.2.1.2.2.1.3.7


Index in mib ii

Index in MIB II

  • ifEntry{ifIndex}

  • atEntry{atNetIfIndex, atNetAddress}

  • ipAddrEntry{ipAdEntAddr }

  • ipRouteEntry{ipRouteDest}

  • ipNetToMediaEntry{ipNetToMediaIfIndex,

    ipNetToMediaNetAddress}

  • tcpConnEntry

    {tcpConnLocalAddress, tcpConnLocalPort,

    tcpConnRemoteAddress, tcpConnRemotePort}

  • udpEntry{udpLocalAddress, udpLocalPort}

  • egpNeighEntry{egpNeighAddr}


Index example

Index Example

  • To get the state of the TCP connection:

    10.144.18.118:1200 ===> 10.144.14.40:1600

     Use snmp_get_req. to get the “tcpConnState” of the tcpConnTable in MIB II.

    tcpConnState ==> .1.3.6.1.2.1.6.13.1.1

.1.3.6.1.2.1.6.13.1.1.10.144.18.118.1200.10.144.14.40.1600


Mib ii

MIB II

  • System Group

    • Provide general information about the managed system.

  • InterfacesGroup

    • Contains generic information about the physical interfaces.

  • Address-TranslationGroup

    • Contains information about the mapping between network addresses and physical addresses for each physical interface.

  • IPGroup

    • Contains information about the implementation and operation of IP at the managed system.

  • ICMPGroup

    • Contains information about the implementation and operation of ICMP at the managed system.


Mib ii cont

MIB-II (cont.)

  • TCPGroup

    • Contains information about the implementation and operation of TCP at the managed system.

  • UDPGroup

    • Contains information about the implementation and operation of UDP at the managed system.

  • EGPGroup

    • Contains information about the implementation and operation of EGP at the managed system.

  • TransmissionGroup

    • Provides details about the underlying transmission media for each interface.

  • SNMPGroup

    • Provides the statistics of SNMP operations at the managed system.


Ietf mibs

IETF MIBs

  • 1213MIB-II

  • 1316Character Stream

  • 1317RS-232-like Hardware

  • 1471PPP

  • 1513RMON for Token Ring

  • 1757RMON

  • 2021RMON-II

  • .....


3 snmp

Message ::=

SEQUENCE {

versionINTEGER {version-1(0)},

communityOCTET STRING,

data ANY

}

Version

Community

SNMP PDU

3. SNMP

  • SNMP Message

    • Version Identifier

    • Community Name

    • Protocol Data Unit

  • The length of SNMP messages should not exceed 484 octets.


Snmp authentication

SNMP Authentication

  • Community

    • Relationship between an Agent and Managers.

  • Community Name

    • Used to validate the SNMP messages.

    • SNMP Password.

    • Default ‘Get’ community name: “public”.

  • Authentication Failure

    • Agent sends “Authentication Failure Trap” to Manager.


Snmp pdu

SNMP PDU

PDU ::= SEQUENCE {

request-id INTEGER,

error-status INTEGER {

noError(0),

tooBig(1),

noSuchName(2),

badValue(3),

readOnly(4)

genErr(5)},

error-index INTEGER,

variable-bindings

SEQUENCE OF {

nameObjectName,

valueObjectSyntax

}

}

Five SNMP PDUs:

GetRquest :

GetNextRequest :

GetResponse :

SetRequest :

Trap :

[0] PDU

[1] PDU

[2] PDU

[3] PDU

[4] Trap-PDU

PDU: Protocol Data Unit


Snmp pdu cont

GetRequest, GetNextRequest, SetRequest

PDU type

request-id

0

0

variable-bindings

GetResponse

PDU type

request-id

variable-bindings

error-status

error-index

variable-bindings

. . .

name

name

name

value

value

value

SNMP PDU (cont.)


Trap pdu

Trap-PDU

  • Enterprise:

    • Type of Object generating trap.

  • AgentAddress:

    • Address of object generating trap.

  • GenericTrap:

    • Generic trap type.

  • SpecificTrap:

    • Enterprise specific trap.

  • TimeStamp:

    • Time elapsed between the last

    • initialization of the network entity and

    • the generation of the trap.

  • VariableBindings

    • “Interesting” information

Trap-PDU ::= [4]

IMPLICIT SEQUENCE {

enterprise OBJECT IDENTIFIER,

agent-addr NetworkAddress,

generic-trapINTEGER {

coldStart(0),

warmStart(1),

linkDown(2),

linkUp(3),

authenticationFailure(4),

egpNeighborLoss(5),

enterpriseSpecific(6)},

specific-trapINTEGER,

time-stampTimeTicks,

variable-bindingsVarBindList

}

generic-trap

time-stamp

specific-trap

PDU type

agent-addr

enterprise

variable-bindings


How does a manager do

Sends Request

PDU to Agent

Received Response

PDU from Agent

How does a Manager do?

Translates Internal

Data to

ASN.1 Format

NM

Application

Agent

Translates ASN.1

Package to Internal

Data Format

NM

Application

Agent

Manager


How does an agent do

Received SNMP

Request PDU

from Manager

Translates ASN.1

Structure to

Internal Data

Maps MIB

Variables to

Internal Variables

Sends SNMP

Response PDU

to Manager

Translates Response

PDU to ASN.1

Format

Implement SNMP

Request to Set or

Get MIB Value

How does an Agent do?

From

Manager

To

Manager

Agent


Main loop of agent

Main Loop of Agent

  • Agent waits for an incoming datagram in Port 161

  • Reads the datagram from UDP and notes the transport address of the sending entity.

  • Increments the QUANTUM to keep track of the logical request-id being processed by agent

  • De-serializes the datagram into an ASN.1 structure. If error occurs, log error and discard packet.

  • The ASN.1 structure is translated into SNMP message. If error occurs, log error and discard packet.

  • Check on VERSION-NUMBER field. If error occurs, log error and discard packet.


Main loop of agent cont

Main Loop of Agent (cont.)

  • Community name is looked up.

    If community is unknown to agent, agent send AUTHENTICATION trap to Manager station in Port 162; log error and discard packet.

  • Agent loops through list of variables in the request.

    If no prototype is found, return a GET-RESPONE with error noSuchName and discard package.

    Once prototype is fund, operation is checked against community profile. If mismatch occurs, return get-respone with error noSuchName or readOnly and discard package.

    Otherwise, agent invokes access routine to perform the desired operation.


What s new in snmpv2

What's New in SNMPv2

  • No more Trap PDU, 3 New PDUs:

    • getBulkReq, InformReq, SNMPv2-Trap

  • Added Security

  • 18 Error Status Values

  • SNMPv2 SMI / SNMPv2 MIB

  • M-to-M Communications

  • Table Operations

  • ...


4 snmp application examples

4. SNMP Application Examples

  • SNMP Commands

    • snmpget [options] node variable [...]

      • query a node using SNMP Get request

    • snmpnext [options] node variable [...]

      • query a node using SNMP GetNext request

    • snmpwalk [options] node variable

      • query a node repeatedly using SNMP GetNext/GetBulk requests

    • snmptrap [-d] [-p port] [-c community] node enterprise agent-addr generic-trap specific-trap time-stamp variable type value [variable type value...]

      • issue an SNMP Version 1 Trap

    • options:[-d] [-t timeout] [-r retries] [-p port] [-c community] [-v version]


Example for snmpget

Example for snmpget

>>snmpget-d 10.144.18.118 .1.3.6.1.2.1.1.1.0

Transmitted 41 bytes to camry (10.144.18.118) port 161:

Initial Timeout: 0.80 seconds

0: 30 27 02 01 00 04 06 70 75 62 6c 69 63 a0 1a 02 0'.....public...

16: 02 18 bc 02 01 00 02 01 00 30 0e 30 0c 06 08 2b .........0.0...+

32: 06 01 02 01 01 01 00 05 00 -- -- -- -- -- -- -- ................

0: SNMP MESSAGE (0x30): 39 bytes

2: INTEGER VERSION (0x2) 1 bytes: 0 (SNMPv1)

5: OCTET-STR COMMUNITY (0x4) 6 bytes: "public"

13: GET-REQUEST-PDU (0xa0): 26 bytes

15: INTEGER REQUEST-ID (0x2) 2 bytes: 6332

19: INTEGER ERROR-STATUS (0x2) 1 bytes: noError(0)

22: INTEGER ERROR-INDEX (0x2) 1 bytes: 0

25: SEQUENCE VARBIND-LIST (0x30): 14 bytes

27: SEQUENCE VARBIND (0x30): 12 bytes

29: OBJ-ID (0x6) 8 bytes: .1.3.6.1.2.1.1.1.0

39: NULL (0x5) 0 bytes


Example for snmpget cont

Example for snmpget (cont.)

Received 69 bytes from camry (10.144.18.118) port 161:

0: 30 43 02 01 00 04 06 70 75 62 6c 69 63 a2 36 02 0C.....public.6.

16: 02 18 bc 02 01 00 02 01 00 30 2a 30 28 06 08 2b .........0*0(..+

32: 06 01 02 01 01 01 00 04 1c 53 75 6e 20 53 4e 4d .........Sun SNM

48: 50 20 41 67 65 6e 74 2c 20 53 55 4e 57 2c 55 6c P Agent, SUNW,Ul

64: 74 72 61 2d 31 -- -- -- -- -- -- -- -- -- -- -- tra-1...........

0: SNMP MESSAGE (0x30): 67 bytes

2: INTEGER VERSION (0x2) 1 bytes: 0 (SNMPv1)

5: OCTET-STR COMMUNITY (0x4) 6 bytes: "public"

13: RESPONSE-PDU (0xa2): 54 bytes

15: INTEGER REQUEST-ID (0x2) 2 bytes: 6332

19: INTEGER ERROR-STATUS (0x2) 1 bytes: noError(0)

22: INTEGER ERROR-INDEX (0x2) 1 bytes: 0

25: SEQUENCE VARBIND-LIST (0x30): 42 bytes

27: SEQUENCE VARBIND (0x30): 40 bytes

29: OBJ-ID (0x6) 8 bytes: .1.3.6.1.2.1.1.1.0

39: OCTET-STR (0x4) 28 bytes: "Sun SNMP Agent, SUNW,Ultra-1"

system.sysDescr.0 : DISPLAY STRING- (ascii): Sun SNMP Agent, SUNW,Ultra-1


Example of snmpwalk

Example of snmpwalk

  • snmpwalk 10.144.18.118 .1.3.6.1.2.1.1

    system.sysDescr.0 : DISPLAY STRING- (ascii): Sun SNMP Agent, SUNW,Ultra-1

    system.sysObjectID.0 : OBJECT IDENTIFIER: .iso.org.dod.internet.private.enterprises.42.2.1.1

    system.sysUpTime.0 : Timeticks: (198219958) 22 days, 22:36:39.58

    system.sysContact.0 : DISPLAY STRING- (ascii): [email protected]

    system.sysName.0 : DISPLAY STRING- (ascii): camry

    system.sysLocation.0 : DISPLAY STRING- (ascii): Information Technology Laboratory 3F

    system.sysServices.0 : INTEGER: 72(01001000)B


Example of snmptrap

Example of snmptrap

  • snmptrap-d manager .1.3.6.1.4.1.612.1.1 10.144.18.116 6 99999 0 .1.3.6.1.1 octetstringascii "Trap test"

    Transmitted 64 bytes to manager (10.144.18.100) port 162:

    0: 30 3e 02 01 00 04 06 70 75 62 6c 69 63 a4 31 06 0>.....public.1.

    16: 09 2b 06 01 04 01 84 64 01 01 40 04 0a 90 12 74 .+.....d..@....t

    32: 02 01 06 02 03 01 86 9f 43 01 00 30 13 30 11 06 ........C..0.0..

    48: 04 2b 06 01 01 04 09 54 72 61 70 20 74 65 73 74 .+.....Trap test

    0: SNMP MESSAGE (0x30): 62 bytes

    2: INTEGER VERSION (0x2) 1 bytes: 0 (SNMPv1)

    5: OCTET-STR COMMUNITY (0x4) 6 bytes: "public"

    13: V1-TRAP-PDU (0xa4): 49 bytes

    15: OBJ-ID ENTERPRISE (0x6) 9 bytes: .1.3.6.1.4.1.612.1.1

    26: IPADDRESS AGENT-ADDR (0x40) 4 bytes: 10.144.18.116 (manager2)

    32: INTEGER GENERIC-TRAP (0x2) 1 bytes: 6

    35: INTEGER SPECIFIC-TRAP (0x2) 3 bytes: 99999

    40: TIMETICKS TIME-STAMP (0x43) 1 bytes: 0 (0x0)

    43: SEQUENCE VARBIND-LIST (0x30): 19 bytes

    45: SEQUENCE VARBIND (0x30): 17 bytes

    47: OBJ-ID (0x6) 4 bytes: .1.3.6.1.1

    53: OCTET-STR (0x4) 9 bytes: "Trap test"


Get system information

Get System Information

  • Get “System Group” of MIB II

  • Use get_request or get_next_request

    sysDescr .1.3.6.1.2.1.1.1.0

    sysObjectID.1.3.6.1.2.1.1.2.0

    sysUptime.1.3.6.1.2.1.1.3.0

    sysContact.1.3.6.1.2.1.1.4.0

    sysName .1.3.6.1.2.1.1.5.0

    sysLocation.1.3.6.1.2.1.1.6.0


Get interface information

Get Interface Information

  • Get “Interface Group” of MIB II

  • Repeatedly Use “get_next_request”

  • Note: We don’t know the ifIndex values in ifTable.

    • First get the next object of .ifTable.ifEntry.0

    • Then repeatedly “get_next”

    • Until the whole subtree is visited.


Traffic monitoring

Traffic Monitoring

  • Get “ifInOctets” and “ifOutOctets” of MIB II Interface Group

  • t1: C1t2: C2

(C2 - C1 )  8

 100%

Utilization (%) =

(t2 - t1)  Bandwidth


6 reference

6. Reference

  • The Simple Book, marshall T.Rose, Prentice-Hall Inc.

  • SNMP, SNMPv2 and RMON: The Practical Guide to Network Management, Willeam Stallings

  • SMI; http://ds.internic.net/rfc/rfc1155.txt

  • Concise MIB Format; http://ds.internic.net/rfc/rfc1212.txt

  • SNMP; http://ds.internic.net/rfc/rfc1157.txt

  • MIB II; http://ds.internic.net/rfc/rfc1213.txt

  • Trap Format; http://ds.internic.net/rfc/rfc1215.txt

  • ASN.1 and BER; ITU-T X.208, X.209


Development of snmp standards

Development of SNMP Standards

  • SNMPv2  SNMPv3

  • RMON I

  • RMON II


Snmpv3

SNMPv3

  • An Architecture for Describing Internet Management Frameworks

  • Local Processing Model for version 3 of the Simple Network Management Protocol (SNMPv3)

  • Message Processing and Control Model for version 3 of the Simple Network Management Protocol (SNMP)

  • User-based Security Model for version 3 of the Simple Network Management Protocol (SNMPv3)

  • View-based Access Control Model (VACM) for version 3 of the Simple Network Management Protocol (SNMP)

  • User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)


Rmon i ii

RMON I & II


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