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SNMP Communication and Functional Models

2. Overview. ? We have covered the organization and information models of SNMPv1.? Here we will address the SNMPv1 communication and functional models? SNMPv1 does not formally define a functional model? What was the functional model?? Deals with the user oriented requirements: (configuration,

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SNMP Communication and Functional Models

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    1. 1 SNMP Communication and Functional Models

    2. 2 Overview • We have covered the organization and information models of SNMPv1. • Here we will address the SNMPv1 communication and functional models • SNMPv1 does not formally define a functional model – What was the functional model? • Deals with the user oriented requirements: (configuration, fault, performance, security, and accounting) – The functions are actually built in the community based access policy of the SNMP administrative model

    3. 3 SNMP Architecture

    4. 4 SNMP Messages Get-Request Get-Next-Request Set-Request Get-Response Trap Generic trap Specific trap

    5. 5 SNMP Trap Messages • Generic trap – coldStart – warmStart – linkDown – linkUp – authenticationfailure – egpNeighborLoss – enterpriseSpecific • Specific trap – for special measurements such as statistics • Time stamp: Time since last initialization

    6. 6 Administrative Model Based on community profile and policy SNMP Entities: SNMP application entities - Reside in management stations and network elements - Manager and agent SNMP protocol entities - Communication processes (PDU handlers) - Peer processes that support application entities

    7. 7 SNMP Community Security in SNMPv1 is community-based Authentication scheme in manager and agent Community: Pairing of two application entities Community name: String of octets Two applications in the same community communicate with each other Application could have multiple community names Communication is not secured in SNMPv1 - no encryption

    8. 8 SNMP Community 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.

    9. 9 SNMP Community

    10. 10 Community Profile MIB view An agent is programmed to view only a subset of managed objects of a network element Access mode Each community name is assigned an access mode:: read-only and read-write Community profile = MIB view + access mode Operations on an object determined by community profile and the access mode of the object Total of four access privileges Some objects, such as table and table entry are non-accessible

    11. 11 Community Profile

    12. 12 Access Policy Administration model is SNMP access policy SNMP community paired with SNMP community profile is SNMP access policy

    13. 13 Access Policy

    14. 14

    15. 15 Proxy Access Policy

    16. 16 Protocol Entities

    17. 17 Default UDP Ports for SNMP

    18. 18 Protocol Entities

    19. 19 SNMP Message SNMP Message Version Identifier Community Name Protocol Data Unit The length of SNMP messages should not exceed 484 octets.

    20. 20 SNMP PDUs

    21. 21 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 { name ObjectName, value ObjectSyntax } }

    22. 22 SNMP PDU (cont.)

    23. 23

    24. 24 Trap-PDU

    25. 25 Trap Type

    26. 26 Generic Trap Example Enterprise: .1.3.6.1.4.1.311.1.1.3.1.1 Agent-Address: 10.10.13.137 Generic-Trap: 4 Specific-Trap: 0 Timestamp: 29756264 #VarBinds: 0

    27. 27 Enterprise-Specific Traps Traps defined by enterprises Identification of Enterprise-Specific Traps Enterprise ? Enterprise OID Generic-Trap ? 6 Specific-Trap ? an Integer

    28. 28 Enterprise Trap Example Enterprise: .1.3.6.1.4.1.522 Agent-Address: 10.10.13.24 Generic-Trap: 6 Specific-Trap: 4 Timestamp: 143739963 VariableBindings: (4) .1.3.6.1.4.1.522.3.14.23.1.2.11687128: 02:18:25 .1.3.6.1.4.1.522.3.14.23.1.3.11687128: 14 .1.3.6.1.4.1.522.3.14.23.1.4.11687128: (Info): Station 00092d142581 Associated .1.3.6.1.4.1.522.3.14.23.1.5.11687128: AssociationOK

    29. 29

    30. 30 Get-Next Request

    31. 31 Get-Next Request

    32. 32

    33. 33

    34. 34 Get-Next Requests with Indices

    35. 35 SNMP Get-Request Example >>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

    36. 36 SNMP Get-Response Example Received 69 bytes from 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

    37. 37 SNMP-Walk - Use of SNMP Get-Next Request 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): lino@ms.chttl.com.tw system.sysName.0 : DISPLAY STRING- (ascii): camry system.sysLocation.0 : DISPLAY STRING- (ascii): Information Technology Laboratory 3F system.sysServices.0 : INTEGER: 72 (01001000)B

    38. 38 SNMP Trap Example Transmitted 64 bytes to 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 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"

    39. 39 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

    40. 40 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.

    41. 41 Traffic Monitoring Get “ifInOctets” and “ifOutOctets” of MIB II Interface Group t1: C1 t2: C2

    42. 42

    43. 43

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