Chapter 9 Network Management

Transcription

1 Chapter 9 Network Management A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: If you use these slides (e.g., in a class) in substantially unaltered form, that you mention their source (after all, we d like people to use our book!) If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR All material copyright J.F Kurose and K.W. Ross, All Rights Reserved Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley, July Network Management 9-1

2 Chapter 9: Network Management Chapter goals: introduction to network management motivation major components Internet network management framework MIB: management information base SMI: data definition language SNMP: protocol for network management security and administration presentation services: ASN.1 Network Management 9-2

3 Chapter 9: Network Management Chapter goals: introduction to network management motivation major components Internet network management framework MIB: management information base SMI: data definition language SNMP: protocol for network management security and administration presentation services: ASN.1 Network Management 9-3

4 Motivation Detecting failure of an interface card at a host or a router Host monitoring Monitoring traffic to aid in resource deployment Network Management 9-4

5 Motivation Detecting rapid changes in routing tables Route flapping due to instability in routing or misconfigured router Monitoring for SLAs Increased interest in traffic monitoring to check for compliance with SLAs Check for service availability (outage), latency, throughput, and outage notification Intrusion detection Notified of traffic from/to suspicious sources Detect certain type of traffic typical of security attack Network Management 9-5

6 Chapter 9: Network Management Chapter goals: introduction to network management motivation major components Internet network management framework MIB: management information base SMI: data definition language SNMP: protocol for network management security and administration presentation services: ASN.1 Network Management 9-6

7 Areas of Network Management 1. Performance Management To quantify, measure, report, analyze, and control performance (utilization and throughput) 2. Fault Management To log, detect, and respond to fault conditions in the network 3. Configuration Management To allow a network manager track which devices are on the managed network and the hardware and software configuration of these devices 4. Accounting Management Allows the network manager to specify, log, and control user and device access to network resources 5. Security Management To control access to network resources according to some well-defined policy Network Management 9-7

8 Scope of Study Will cover The infrastructure of network management The overall architecture Network management protocols Information base Will not cover: Decision-making processes of network administrators Fault identification and management Proactive anomaly detection Alarm correlation Service management Provisioning of resources, such as: bandwidth, server capability and other computational/communication resources Network Management 9-8

9 Chapter 9 outline What is network management? Internet-standard management framework Structure of Management Information: SMI Management Information Base: MIB SNMP Protocol Operations and Transport Mappings Security and Administration ASN.1 Network Management 9-9

10 What is network management? autonomous systems (aka network ): 100s or 1000s of interacting hardware/software components other complex systems requiring monitoring, control: jet airplane nuclear power plant others? "Network management includes the deployment, integration and coordination of the hardware, software, and human elements to monitor, test, poll, configure, analyze, evaluate, and control the network and element resources to meet the real-time, operational performance, and Quality of Service requirements at a reasonable cost." Network Management 9-10

11 Infrastructure for Network Management The hardware and software components to give the network administrator to "Network monitor, management test, poll, configure, includes the.. deployment,. and integration control and coordination of the hardware, software, and human elements to monitor, test, poll, configure, analyze, evaluate, and control the network and element resources to meet the realtime, operational performance, and Quality of Service requirements at a reasonable cost." Network Management 9-11

12 Infrastructure for network management definitions: managing entity managing entity data network management protocol agent agent data managed device data managed device managed devices contain managed objects whose data is gathered into a Management Information Base (MIB) agent data managed device agent data managed device Network Management 9-12

13 Infrastructure for network management definitions: managing entity managing entity data network management protocol agent agent data managed device data managed device managed devices contain managed objects whose data is gathered into a Management Information Base (MIB) agent data managed device agent data managed device Network Management 9-13

14 1. Managing Entity An application running in a centralized network management station in the NOC. It is the locus of activity for network management information At managing Entity: actions are initiated to control network behavior, and the human network administrator interacts with network devices Network Management 9-14

15 2. Managed Devices Network equipment (including software) that resides on a managed network Might be a host, router, bridge, hub, printer, or modem Within a managed device, there are: several managed objects Network management agent Network Management 9-15

16 Managed Objects Managed objects are: Actual pieces of hardware within the managed device (e.g. NIC) The sets of configuration parameters for the pieces of hardware and software (e.g. an intradomain routing protocol such as RIP) Information associated with Managed objects are collected into a Management Information Base (MIB) Network Management 9-16

17 Network Management Agent A process running in the manged device Communicates with the managing entity Taking local actions at the managed device Under the command and control of the managing entity Network Management 9-17

18 3. Network Management Protocol Runs between the managing entity and the managed devices Allows the managing entity to query the status of managed devices Allows agents to report exceptional events to managing entity (e.g. component failure or violation of performance thresholds) Indirectly take actions at these devices via its agents Network Management 9-18

19 3. Network Management Protocol Does not manage the network Provide a tool with which the network administrator can manage Network Management 9-19

20 Network Management standards OSI CMISE/CMIP o Common Management Information Services Element/Common Management Information Protocol designed 1980 s: the unifying net management standard too slowly standardized SNMP: Simple Network Management Protocol Internet roots (SGMP) started simple Independent of vendorspecific products deployed, adopted rapidly growth: size, complexity currently: SNMP V3 de facto network management standard Network Management 9-20

21 Chapter 9 outline What is network management? Internet-standard management framework Structure of Management Information: SMI Management Information Base: MIB SNMP Protocol Operations and Transport Mappings Security and Administration ASN.1 Network Management 9-21

22 Framework for Network Management Should address the following questions: What is being monitored? And what form of control can be exercised by the network administrator? What is the specific form of the information that will be reported and/or exchanged? What is the communication protocol for exchanging this information? Network Management 9-22

23 SNMP overview: 4 key parts Definitions of Network Management Objects Management information base (MIB) Data Definition Language Structure of Management Information (SMI): SNMP protocol convey manager<->managed object info, commands Security, administration capabilities major addition in SNMPv3 Network Management 9-23

24 SNMP overview: 4 key parts Management information base (MIB): distributed information store of network management data Structure of Management Information (SMI): data definition language for MIB objects defines data types, object model, and rules for writing and revising management information SNMP protocol convey manager<->managed object info, commands security, administration capabilities major addition in SNMPv3 Network Management 9-24

25 SNMP overview: 4 key parts Management information base (MIB): distributed information store of network management data Structure of Management Information (SMI): data definition language for MIB objects SNMP protocol convey manager<->managed object info, commands security, administration capabilities major addition in SNMPv3 Network Management 9-25

26 Network Management Objects Also known as Management Information Base (MIB) objects Management information is represented as a collection of managed objects that together form a virtual information store, known as the MIB Network Management 9-26

27 Network Management Objects An MIB object may be: A counter: such as the number of IP datagrams discarded at a router due to errors in an IP datagram header, or Carrier sense errors in an Ethernet interface card Descriptive information: such as the version of the software running on a DNS server Status information: such as whether a particular device is functioning correctly; or Protocol-specific information: such as a routing path to a destination. Network Management 9-27

28 MIB Objects MIB Objects define the management information maintained by a managed device Related MIB objects are gathered into MIB modules Network Management 9-28

29 SNMP overview: 4 key parts Management information base (MIB): distributed information store of network management data Structure of Management Information (SMI): data definition language for MIB objects SNMP protocol convey manager<->managed object info, commands security, administration capabilities major addition in SNMPv3 Network Management 9-29

30 SMI What: language to define the management information residing in a managed-network entity Purpose: syntax, semantics of management data welldefined, unambiguous SMI hierarchy Base data types in the SMI How managed objects are described in SMI How related managed objects are grouped into modules Network Management 9-30

31 SMI Base Data Types SMI is based on ASN.1 object-definition language Many SMI-specific data types were added to justify consider it a data definition language RFC 2578 defines 11 basic data types: INTEGER, Integer32, Unsigned32, OCTET STRING, OBJECT IDENTIFIER, IPaddress, Counter32, Counter64, Guage32, Time Ticks, Opaque Also possible to impose a tabular structure on an ordered collection of MIB objects using the SEQUENCE OF construct Network Management 9-31

32 SMI: data definition language Purpose: syntax, semantics of management data welldefined, unambiguous base data types: straightforward, boring OBJECT-TYPE data type, status, semantics of managed object MODULE-IDENTITY groups related objects into MIB module Basic Data Types INTEGER Integer32 Unsigned32 OCTET STRING OBJECT IDENTIFIER IPaddress Counter32 Counter64 Guage32 Time Ticks Opaque Network Management 9-32

33 SMI Higher-Level Construct OBJECT-TYPE Construct: Used to specify the data type, status, and semantics of a managed object Collectively, these managed objects contain the management data that lie at the heart of network management Has four clauses: SYNTAX: Basic data types associated with object MAX-ACCESS: be read, be written, or be created STATUS: current, obsolete, or deprecated DESCRIPTION: textual definition of the object Network Management 9-33

34 OBJECT-TYPE: ipindelivers ipindelivers OBJECT TYPE SYNTAX Counter32 keeps track of the number of IP datagrams that were received at the MAX-ACCESS read-only managed deviceand were successfully STATUS current delivered to an upper layer protocol DESCRIPTION The total number of input datagrams successfully delivered to IP userprotocols (including ICMP) ::= { ip 9} ipindelivers defines a 32-bit counter that Network Management 9-34

35 SMI Higher-Level Construct MODULE-IDENTITY Construct: Allows related objects to be grouped together within a module Contains clauses to document contact information of the author of the module, date of last update, a revision history, and a textual description of the module Network Management 9-35

36 ipmib MODULE-IDENTITY: Module definition for management of the IP protocol ipmib MODULE-IDENTITY LAST-UPDATED Z ORGANZATION IETF SNPv2 Working Group CONTACT-INFO Keith McCloghrie DESCRIPTION The MIB module for managing IP and ICMP implementations, but excluding their management of IP routes. REVISION Z DESCRIPTION The initial revision of this MIB module was part of MIB-II. ::= {mib-2 48} Network Management 9-36

37 SMI Higher-Level Construct NOTIFICATION-TYPE Construct: Used to specify information regarding SNMPv2-Trap and InformationRequest messages generated by an agent or a managing entity Contains a textual DESCRIPTION of when such messages are to be sent, and a list of values to be included in the message generated. Network Management 9-37

38 SNMP MIB MIB module specified via SMI MODULE-IDENTITY (100 standardized MIBs, more vendor-specific) MODULE OBJECT TYPE: OBJECT TYPE: OBJECT TYPE: objects specified via SMI OBJECT-TYPE construct Network Management 9-38

39 SMI: Object, module examples OBJECT-TYPE: ipindelivers ipindelivers OBJECT TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION The total number of input datagrams successfully delivered to IP userprotocols (including ICMP) ::= { ip 9} MODULE-IDENTITY: ipmib ipmib MODULE-IDENTITY LAST-UPDATED Z ORGANZATION IETF SNPv2 Working Group CONTACT-INFO Keith McCloghrie DESCRIPTION The MIB module for managing IP and ICMP implementations, but excluding their management of IP routes. REVISION Z ::= {mib-2 48} Network Management 9-39

40 Management Information Base (MIB) A virtual information store, holding managed objects whose values collectively reflect the current state of the network Managing entity may query and/or set these values by sending SNMP messages to the agent that is executing in a managed device Managed objects are: specified using the OBJECT-TYPE SMI construct, gathered into MIB modules using the MODULE- IDENTITY construct Network Management 9-40

41 MIB Modules Standardization Efforts by IETF Standard modules associated with routers, hosts, and other network equipment Standardization includes: Basic identification data Management information about the device s network interfaces and protocols Network Management 9-41

42 MIB Modules Standardization >100 standards-based MIB modules 100s of vendor-specific MIB modules IETF adopted a standardized object identification (naming) framework Adopted by the ISO as a part of ASN.1 Objects (data format, protocol, or piece of information) were standardized regardless of the Network standards organization (IETF, ISO, IEEE, or ANSI) Equipment manufacturer, or Network owner Network Management 9-42

43 ASN.1 Object Identifier Tree Objects are named in a hierarchal manner Each branch point in the tree has a name and a number Any point is identifiable by the pathsequence (names or numbers) from the root to that point Network Management 9-43

44 OSI Object Identifier Tree USA RSA Microsoft Microsoft Word Definitions of standardized MIB modules (RFC3600) >4000 companies registered with the Internet Assigned Numbers Authority (IANA) Check out Network Management 9-44

45 Standardized MIB Modules RFC 3600 lists standardized MIB modules Managed objects falling under system contain general information about the device being managed All managed devices must support the system MIB objects Next slide defines the managed objects in the MIB module for the UDP protocol at the managed entity Network Management 9-45

46 MIB example: UDP module Object ID Name Type Comments UDPInDatagrams Counter32 total # datagrams delivered at this node UDPNoPorts Counter32 # underliverable datagrams no app at portl UDInErrors Counter32 # undeliverable datagrams all other reasons UDPOutDatagrams Counter32 # datagrams sent udptable SEQUENCE one entry for each port in use by app, gives port # and IP address Network Management 9-46

47 SNMP Naming question: how to name every possible standard object (protocol, data, more..) in every possible network standard?? answer: ISO Object Identifier tree: hierarchical naming of all objects each branchpoint has name, number ISO ISO-ident. Org. US DoD Internet udpindatagrams UDP MIB2 management Network Management 9-47

48 SNMP Protocol Operations SNMPv2 is used to convey MIB information among managing entities and agents Most common usage of SNMP is in a request-response An mode unsolicited message to notify a managing entity of an exceptional An SNMPv2 managing entity sends a request to an SNMPv2 agent, situation who that performs has resulted some in actions changes to MIB object values and sends a reply to the request. Typically, a request will be used to: query (retrieve) or modify (set) MIB object values associated with a managed device Send a trap message to a managing entity Network Management 9-48

49 SNMP protocol Two ways to convey MIB info, commands: request managing entity response agent data managing entity trap msg agent data Managed device request/response mode Managed device trap mode Network Management 9-49

50 SNMPv2 Messages SNMPv2 defines 7 types of PDUs 1. GetRequest 2. GetNextRequest 3. GetBulkRequest 4. InformRequest 5. SetRequest 6. Response 7. SNMPv2-Trap Network Management 9-50

51 SNMP protocol: message types Message type GetRequest GetNextRequest GetBulkRequest InformRequest SetRequest Response Trap Function Mgr-to-agent: get me data (instance,next in list, block) Mgr-to-Mgr: here s MIB value Mgr-to-agent: set MIB value Agent-to-mgr: value, response to Request Agent-to-mgr: inform manager of exceptional event Network Management 9-51

52 SNMP protocol: message types Requests an arbitrary Used to set sequence of Message typeallows through MIB Function values a large list or table block of MIB of data objects GetRequest to be Mgr-to-agent: returned get me data GetNextRequest (instance,next in list, block) GetBulkRequest InformRequest Sent from a managing entity Mgr-to-Mgr: an agent here s MIB value Requests the value of one or more MIB objects MIBs SetRequest object-identifiers Mgr-to-agent: are specified in set the PDU MIB (variable value binding) Agent Response responds with a Agent-to-mgr: Response PDU, value, containing response the to object identifiers and their Request associated values The three message types differ in the granularity of the request Trap Agent-to-mgr: inform manager of exceptional event Network Management 9-52

53 SNMP protocol: message types Message type Function GetRequest Used by the managing Mgr-to-agent: entity set the get valueme of data one or GetNextRequest more MIB objects in (instance,next a managed device. in list, block) GetBulkRequest Agent replies with a Response PDU, with the noerror InformRequest error status to confirm that the value has indeed been set. Mgr-to-Mgr: here s MIB value SetRequest Response Trap Mgr-to-agent: set MIB value Agent-to-mgr: value, response to Request Agent-to-mgr: inform manager of exceptional event Network Management 9-53

54 SNMP protocol: message types Message type GetRequest GetNextRequest GetBulkRequest InformRequest Function Mgr-to-agent: get me data (instance,next in list, block) Mgr-to-Mgr: here s MIB value Used SetRequest by the managing Mgr-to-agent: entity notify another set MIB managing value entity of MIB information that is remote to the receiving entity Response Agent-to-mgr: value, response Receiving entity replies to Request with a Response PDU, with the noerror error status to acknowledge receipt of the InformRequest Trap PDU. Agent-to-mgr: inform manager of exceptional event Network Management 9-54

55 SNMP protocol: message types Message type Function GetRequest Mgr-to-agent: get me data GetNextRequest Generated asynchronously (instance,next in list, block) GetBulkRequest Not in response to a received request; but In response to an event for which the managing entity needs notification InformRequest Well-known trap types are: Mgr-to-Mgr: here s MIB value Cold or warm start by a device, A SetRequest link going up (or down), The loss of a neighbor, or An authentication failure event Mgr-to-agent: set MIB value Response Agent-to-mgr: value, response A trap message has no required to Request a response from a managing entity Trap Agent-to-mgr: inform manager of exceptional event Network Management 9-55

56 SNMP protocol: message types Message type GetRequest GetNextRequest GetBulkRequest InformRequest SetRequest Response Trap Function Mgr-to-agent: get me data (instance,next in list, block) Mgr-to-Mgr: here s MIB value Mgr-to-agent: set MIB value Agent-to-mgr: value, response to Request Agent-to-mgr: inform manager of exceptional event Network Management 9-56

57 SNMP Message SNMP PDU is typically carried in the payload of a UDP datagram UDP is the preferred transport mapping. RFC1906 UDP is unreliable Request ID field is used by the managing entity to number its requests to an agent An agent s response takes its response ID from that of the received request Thus managing entity can detect lost requests or replies SNMP does not mandate any procedure for retransmission Network Management 9-57

58 SNMP protocol: message formats Network Management 9-58

59 SNMP Security and Administration SNMPv3 = SNMPv2 + Security + Admin Lack of security caused SNMP being used primarily for monitoring (not control)! Network Management 9-59

60 SNMPv3 Architecture SNMP Applications consists of: Command generator Notification receiver Proxy forwarder Typically found in a managing entity Command responder Notification originator Typically found in an agent Possibly other applications Network Management 9-60

61 SNMPv3 Architecture SNMP Applications consists of: Command generator Notification receiver Proxy Generates: forwarder GetRequest GetNextRequest Command responder GetBulkRequest, and Notification SetRequest originator Handles Possibly other Received applications responses to these PDUs Network Management 9-61

62 SNMPv3 Architecture SNMP Applications consists of: Command generator Executes Notification in an agent receiver Receives, Proxy forwarder processes and replies (using Response) to received requests Command responder Notification originator Possibly other applications Network Management 9-62

63 SNMPv3 Architecture SNMP Applications consists of: Received Command and generator processed by: Notification receiver Proxy forwarder Generates Trap PDUs Command responder Notification originator Possibly other applications Network Management 9-63

64 SNMPv3 Architecture SNMP Applications consists of: Command generator Notification receiver Proxy forwarder Forwards Request, Notification, Command Response responder PDUs Notification originator Possibly other applications Network Management 9-64

65 SNMPv3 Architecture SNMP Applications consists of: Command generator Notification receiver Proxy forwarder Command responder Notification originator Possibly other applications Network Management 9-65

66 SNMPv3 Engine and Applications SNMP Application Commander Generator PDU PDU Commander Responder Notification Receiver Notification Originator Proxy Forwarder Other Applications SNMP Engine Dispatching Message Processing System Timeliness, Authentication & Privacy Access Control Transport Layer Network Management 9-66

67 SNMPv3 Engine and Applications SNMP Application SNMP version is determined Commander Notification Generator A PDU is wrapped Receiver in a message header Commander containing: SNMP Responder version number, A message ID, and PDU PDU Message size Notification Originator Proxy Forwarder Other Applications Appropriate Authentication headers SNMP Engine Dispatching Message Timeliness, Processing Authentication Preferred transport protocol = UDP System & Privacy Preferred port number = 161 (port #162 for trap messages) Access Control Transport Layer Network Management 9-67

68 SNMPv3 Engine and Applications SNMP Application Commander Generator Commander Responder Notification Receiver Notification Originator Proxy Forwarder Other Applications SNMP Engine Dispatching Message Processing System Timeliness, Authentication & Privacy Access Control Transport Layer Network Management 9-68

69 SNMPv3 Security SNMP messages are used for: Monitoring (e.g. GetRequest) Control (e.g. SetRequest) An intruder who could intercept/generate SNMP messages could wreak havoc in the network Network Management 9-69

70 User-Based Security SNMPv3 security is called User-Based Security User: identified by a user-name Security information: password, key-value, or access privileges Services: Encryption, authentication, protection against playback attacks, and access control. Network Management 9-70

71 SNMP security and administration encryption: DES-encrypt SNMP message authentication: compute, send MIC(m,k): compute hash (MIC) over message (m), secret shared key (k) protection against playback: use nonce view-based access control SNMP entity maintains database of access rights, policies for various users database itself accessible as managed object! Network Management 9-71

72 Encryption SNMP PDU is encrypted by DES in CBC mode Secret key is shared with the receiving entity, for decryption Network Management 9-72

73 Authentication SNMPv3 uses Hash function (MD5) for authentication It uses along a secret key to provide Hash Message Authentication Code (HMAC) HMAC provides authentication and protection against tampering Network Management 9-73

74 Protection Against Play-Back Receiver requires that the sender include a value in each message that is based on a counter in the receiver The counter functions as a nonce. Counter value = f (time reboot + no. of reboots configuration ) Value is accepted if it is within a small margin of error of the receiver s actual value Network Management 9-74

75 Access Control SNMPv3 provides view-based access control It controls which network management information can be queried or set and by which users Access rights and policies are kept in a Local Configuration Datastore (LCD) Portions of the LCD are accessible as managed objects; Defined in the View-based Access Control Model Configuration MIB Can be managed and manipulated remotely by SNMP Network Management 9-75

76 Chapter 9 outline What is network management? Internet-standard management framework Structure of Management Information: SMI Management Information Base: MIB SNMP Protocol Operations and Transport Mappings Security and Administration The presentation problem: ASN.1 Network Management 9-76

77 ASN.1 Abstract Syntax Notation. One Network Management 9-77

78 The presentation problem Q: does perfect memory-to-memory copy solve the communication problem? A: not always! struct { char code; int x; } test; test.x = 256; test.code= a test.code test.x a host 1 format test.code test.x a host 2 format problem: different data format, storage conventions Network Management 9-78

79 A real-life presentation problem: grandma 2004 teenager aging 60 s hippie Network Management 9-79

80 Presentation problem: potential solutions 1. Sender learns receiver s format. Sender translates into receiver s format. Sender sends. real-world analogy? pros and cons? 2. Sender sends. Receiver learns sender s format. Receiver translate into receiver-local format real-world-analogy pros and cons? 3. Sender translates host-independent format. Sends. Receiver translates to receiver-local format. real-world analogy? pros and cons? Network Management 9-80

81 Solving the presentation problem 1. Translate local-host format to host-independent format 2. Transmit data in host-independent format 3. Translate host-independent format to remote-host format grandma aging 60 s hippie 2005 teenager Network Management 9-81

82 ASN.1: Abstract Syntax Notation 1 ISO standard X.680 used extensively in Internet like eating vegetables, knowing this good for you! defined data types, object constructors like SMI BER: Basic Encoding Rules specify how ASN.1-defined data objects to be transmitted each transmitted object has Type, Length, Value (TLV) encoding Network Management 9-82

83 TLV Encoding Idea: transmitted data is self-identifying T: data type, one of ASN.1-defined types L: length of data in bytes V: value of data, encoded according to ASN.1 standard Tag Value Type Boolean Integer Bitstring Octet string Null Object Identifier Real Network Management 9-83

84 TLV encoding: example Value, 259 Length, 2 bytes Type=2, integer Value, 5 octets (chars) Length, 5 bytes Type=4, octet string Network Management 9-84

85 Network Management: summary network management extremely important: 80% of network cost ASN.1 for data description SNMP protocol as a tool for conveying information Network management: more art than science what to measure/monitor how to respond to failures? alarm correlation/filtering? Network Management 9-85