1. Introduction to SNMP Yen-Cheng Chen http://www.im.ncnu.edu.tw/~ycchen/ ycchen@ncnu.edu.tw

2. Contents 1. Basic Concepts 2. Management Information Base 3. Simple Network Management Protocol 4. SNMP Application Examples 5. Reference Appendix: ASN.1 Concept

3. 3 1. Basic Concepts Internet RMON Device UNIX.... FDDI UNIX Firewall / Router Management Station Management Station....... Polling Notification....... UNIX NMNM

4. 4 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 ) 。

5. 5 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)

6. 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

7. 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.

8. SNMP Architectural Model (cont.) Network 網路介面 SNMP UDP IP 網路介面 SNMP UDP IP 網路介面 SNMP UDP IP ManagerAgent... Management Station HostRouter Network Elements (NEs) Network Management Protocol SNMP

9. 9 Management Components  Manager  Agent  Network Management Protocol  Management Information Base (MIB)

10. 10 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.

11. 11 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).

12. Management Information Base (MIB)  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. 網路介面 SNMP UDP IP Agent Managed Resources MIB NE: Network Element

13. SNMP Services  Four Services  Get, Set, GetNext, Trap  Five SNMP PDUs  GetRequest, SetRequest, GetNextRequest, GetResponse, Trap ManagerAgent(s) Get, Set, GetNext Request Get Response Trap PDU: Protocol Data Unit

14. 14 SNMP Services Get Request Get Response ManagerAgent GetNext Request Get Response ManagerAgent Set Request Get Response ManagerAgent Trap Request ManagerAgent Get GetNext Set Trap Get GetNext Set Trap

15. 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.

16. Get-Next Request :Non-Leaf Object :Leaf Object 123 456 MIB Tree : In SNMP, Only leaf objects have values. ＊

17. Default UDP Ports for SNMP 網路介面 SNMP UDP IP Manager Management Station Network Elements (NEs) 網路介面 SNMP UDP IP Agent 162 Any 161 Any

18. 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

19. 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,...

20. 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 ccitt iso joint-iso-ccitt directory 0 1 2 std reg authority member body org 0 1 2 3 dod internet 6 1 1 2 3 4 mgmt experimental private MIB II system 1 interface 2 at 3 IP 4 ICMP 5 TCP 6 UDP 7 EGP 8 Trans. 10 SNMP 11 1 1 enterprises 1.3.6.1.2.1.2 1.3.6.1.4.1 1.3.6.1.2.1 MIB II interface enterprises

21. 21 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

22. 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 }

23. SMI (cont.) 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 ASN.1 Macro

24. 24 OBJECT-TYPE Example sysDesc OBJECT-TYPE SYNTAX DisplayString (SIZE (0..255)) ACCESS read-only STATUS mandary ::= { system 1}

25. 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 } 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 SMI (cont.)

26. 26 Object Syntax Summary  Simple Syntax  Integer  Octet String  Object Identifier  Null  Application Syntax  Network Address  Counter  Gauge  Time Ticks  Opaque

27. Concise MIB Definition (RFC 1212) OBJECT-TYPE MACRO ::= BEGIN TYPE NOTATION ::= "SYNTAX" type(ObjectSyntax) "ACCESS" Access "STATUS" Status DescrPart ReferPart IndexPart DefValPart VALUE NOTATION ::= value (VALUE ObjectName) 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

28. 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 } 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 } 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 }

29. 29 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

30. 30 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

31. 31 Columnar Objects ifTable OBJECT-TYPE SYNTAX SEQUENCE OF IfEntry … ::= { interface 2 } IfEntry ::= SEQUENCE { ifIndexINTEGER, ifDescrDisplayString, ifTypeINTEGER, … } ifEntry OBJECT-TYPE SYNTAX IfEntry … INDEX {ifIndex } ::= { ifTable 1} ifDescr OBJECT-TYPE SYNTAX DisplayString (SIZE(0..255)) ACCESS read-only STATUS madatory... ::= {ifEntry 2}

32. 32 Columnar Objects ifIndex ifDescr ifType... 1 le0 6... 6 llc0 1... 7 lo0 24... 9 le1 6....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) 1.3.6.1.2.1.2.2.1.3.71.3.6.1.2.1.2.2.1.2.6

33. 33 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}

34. 34 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

35. MIB II  System Group  Provide general information about the managed system.  Interfaces Group  Contains generic information about the physical interfaces.  Address-Translation Group  Contains information about the mapping between network addresses and physical addresses for each physical interface.  IP Group  Contains information about the implementation and operation of IP at the managed system.  ICMP Group  Contains information about the implementation and operation of ICMP at the managed system.

36. MIB-II (cont.)  TCP Group  Contains information about the implementation and operation of TCP at the managed system.  UDP Group  Contains information about the implementation and operation of UDP at the managed system.  EGP Group  Contains information about the implementation and operation of EGP at the managed system.  Transmission Group  Provides details about the underlying transmission media for each interface.  SNMP Group  Provides the statistics of SNMP operations at the managed system.

37. IETF MIBs  1213MIB-II  1316Character Stream  1317RS-232-like Hardware  1471PPP  1513RMON for Token Ring  1757RMON  2021RMON-II .....

38. 3. SNMP  SNMP Message  Version Identifier  Community Name  Protocol Data Unit  The length of SNMP messages should not exceed 484 octets. Message ::= SEQUENCE { versionINTEGER {version-1(0)}, communityOCTET STRING, data ANY } Version Community SNMP PDU

39. 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.

40. 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 } GetRquest : GetNextRequest : GetResponse : SetRequest : Trap : [0] PDU [1] PDU [2] PDU [3] PDU [4] Trap-PDU Five SNMP PDUs: PDU: Protocol Data Unit

41. SNMP PDU (cont.) PDU typerequest-id00variable-bindings GetRequest, GetNextRequest, SetRequest PDU typerequest-id error-statuserror-index variable-bindings GetResponse variable-bindings name value name value name value...

42. Trap-PDU Trap-PDU ::= [4] IMPLICIT SEQUENCE { enterprise OBJECT IDENTIFIER, agent-addr NetworkAddress, generic-trap INTEGER { coldStart(0), warmStart(1), linkDown(2), linkUp(3), authenticationFailure(4), egpNeighborLoss(5), enterpriseSpecific(6)}, specific-trapINTEGER, time-stampTimeTicks, variable-bindingsVarBindList } Enterprise: Type of Object generating trap. Agent Address: Address of object generating trap. Generic Trap: Generic trap type. Specific Trap: Enterprise specific trap. Time Stamp: Time elapsed between the last initialization of the network entity and the generation of the trap. Variable Bindings “Interesting” information PDU type enterprise agent-addr generic - trap variable-bindings specific - trap time-stamp

43. How does a Manager do? Translates Internal Data to ASN.1 Format Sends Request PDU to Agent Translates ASN.1 Package to Internal Data Format Received Response PDU from Agent NM Application NM Application Agent Manager

44. 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 From Manager To Manager Agent

45. 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.

46. 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.

47. What's New in SNMPv2 v No more Trap PDU, 3 New PDUs:  getBulkReq, InformReq, SNMPv2-Trap v Added Security v 18 Error Status Values v SNMPv2 SMI / SNMPv2 MIB v M-to-M Communications v Table Operations v...

48. 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]

49. 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

50. 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

51. 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): 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

52. 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"

53. 53 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

54. 54 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.

55. 55

56. 56 Traffic Monitoring  Get “ifInOctets” and “ifOutOctets” of MIB II Interface Group  t 1 : C 1 t 2 : C 2 (C 2 - C 1 )  8 (t 2 - t 1 )  Bandwidth  100% Utilization (%) =

57. 57

58. 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

59. 59 Development of SNMP Standards  SNMPv2  SNMPv3  RMON I  RMON II

60. 60 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)

61. 61 RMON I & II

62. Appendix: ASN.1 Concepts  ASN.1:  Abstract Syntax Notation One  ISO/ITU-T Standards: ISO 8824/ITU-T X.208  Abstract Syntax:  Use a syntax to define data/data structure independent of machine-oriented structures and restrictions.  Use in SNMP  Define SNMP PDU format  Define management information (MIB)

63. ASN.1 Reserved Words  All reserved words MUST be upper case  BOOLEANINTEGERBITSTRING  OCTETNULLOFSEQUENCE  SETIMPLICITCHOICEANY  EVTERNALOBJECTENDIDENTIFIER  OPTIONALDEFAULTTRUECOMPONTS  FALSEBEGIN

64. 64 What are defined using ASN.1  Types:  data structures  e.g. Counter, Gauge, IpAddess,...  Values:  instances (variables) of a type  e.g. sysContact, ifTable, ifSpeed,...  Macros:  used to change the actual grammar of ASN.1  e.g. OBJECT-TYPE, ACCESS,...

65. Modules  Module: A collection of ASN.1 descriptions  Module Structure DEFINITION ::= BEGIN END  Example EmptyModule DEFINITION ::= BEGIN END

66. Tags and Types  Tags  Every type defined with ASN.1 is assigned a tag  Tag = Class + Number Class: (Bit 8,7 in BER tag) –Universal0 0 –Application0 1 –Context-specific 1 0 –Private 1 1 Number: non-negative Integer BER: Basic Encoding Rules

67. Tags and Types (cont.)  Universal TagASN.1 Type 1BOOLEAN 2INTEGER 3BIT STRING 4OCTET STRING 5NULL 6OBJECT IDENTIFIER 7ObjectDescriptor 8EXTERNAL 9REAL 10ENUMERATED 12-15Reserved 16SEQUENCE, SEQUENCE OF 17SET, SET OF u Universal TagASN.1 Type 18NumericString 19PrintableString 20TeletexString 21VediotextString 22IA5String 23UTCTime 24GeneralizeTime 25GraphicString 26VisssibleString 27GeneralString 28CharacterString 29-...Reserved

68. Values in ASN.1  General format of a value assignment  ::=  Examples:  BOOLEAN Married ::= BOOLEAN currentStatus Married ::= FALSE  INTEGER Color ::= INTEGER{red (0), blue (1), yellow (2)} defaultColor Color ::= 1 defaultColor Color ::= blue

69. Basic Encode Rules  BER  A transfer syntax notation  ISO/ITU-T Standards: ISO 8825/ITU-T X.209  Values from any abstract syntax defined using ASN.1 can be encoded with BER  BER uses Tag, Length, Value (TLV) encoding Tag: “identifier”, Length: length of content, Value: “contents”  Each value may itself be made up of one or more TLV- encoded values TTLTLVV V L