Chapter 13Network Management Applications

Network and Systems Management

Management Applications

• OSI Model • Configuration• Fault• Performance• Security• Accounting

• Reports• Service Level Management• Policy-based management

Configuration Management

• Network Provisioning• Inventory Management

• Equipment • Facilities

• Network Topology• Database Considerations

Network Provisioning

• Network Provisioning• Provisioning of network resources

• Design• Installation and maintenance

• Circuit-switched network• Packet-switched network, configuration for

• Protocol • Performance• QoS

• ATM networks

Network Topology

• Manual• Auto-discovery by NMS using

• Broadcast ping• ARP table in devices

• Mapping of network• Layout• Layering

• Views• Physical• Logical

Network Topology Discovery

163.25.147.0163.25.147.0

163.25.145.0163.25.145.0163.25.145.0163.25.145.0 163.25.146.0163.25.146.0

163.25.146.128163.25.146.128

192.168.12.0192.168.12.0192.168.13.0192.168.13.0

140.112.5.0140.112.5.0

140.112.8.0140.112.8.0140.112.8.0140.112.8.0 140.112.6.0140.112.6.0

Discovery In a Network

What to be discovered in a network ? Node Discovery

The network devices in each network segment Network Discovery

The topology of networks of interest Service Discovery

The network services provided

NetworkNetwork Topology DiscoveryTopology Discovery Network Discovery + Node DiscoveryNetwork Discovery + Node Discovery

Node Discovery

Node Discovery Given an IP Address, find the nodes in

the same network. Two Major Approaches:

Use Ping to query the possible IP addresses.

Use SNMP to retrieve the ARP Cache of a known node.

Use ICMP ECHO

Eg: IP address: 163.25.147.12 Subnet mask: 255.255.255.0 All possible addresses:

163.25.147.1 ~ 163.25.147.254 For each of the above addresses, use

ICMP ECHO to inquire the address If a node replies (ICMP ECHO Reply), then

it is found. Broadcast Ping

Use SNMP

Find a node which supports SNMP The given node, default gateway, or

router Or try a node arbitrarily

Query the iipNetToMediaTablepNetToMediaTable in MIB-II IP group (ARP Cache)

ipNetToMediaIfIndex ipNetToMediaNetAddress

1 00:80:43:5F:12:9A 163.25.147.10 dynamic(3)2 00:80:51:F3:11:DE 163.25.147.11 dynamic(3)

ipNetToMediaPhysAddress ipNetToMediaType

Network Discovery

Network Discovery Find the networks of interest with their

interconnections Key Issue:

Given a network, what are the networks directly connected with it ?

Major Approach Use SNMP to retrieve the routing table

of a router.

Default Router

Routing table

Mapping of network

Traditional LAN Configuration

Physical

Logical

Virtual LAN Configuration

Physical

Logical

Fault Management

• Fault is a failure of a network component• Results in loss of connectivity• Fault management involves:

• Fault detection• Polling• Traps: linkDown, egpNeighborLoss

• Fault location• Detect all components failed and trace

down the tree topology to the source• Fault isolation by network and SNMP tools• Use artificial intelligence /

correlation techniques• Restoration of service• Identification of root cause of the problem• Problem resolution

Performance Management

• Tools• Protocol analyzers• RMON• MRTG

• Performance Metrics• Data Monitoring• Problem Isolation• Performance Statistics

Performance Metrics• Macro-level

• Throughput• Response time• Availability• Reliability

• Micro-level• Bandwidth• Utilization• Error rate• Peak load• Average load

Traffic Flow MeasurementNetwork Characterization

Four levels defined by IETF (RFC 2063)Four levels defined by IETF (RFC 2063)

Network Flow Measurements

• Three measurement entities:• MetersMeters gather data and build tables• Meter readersMeter readers collect data from meters• ManagersManagers oversee the operation

• Meter MIB (RFC 2064)• NetraMet - an implementation(RFC 2123)

Data Monitoring and Problem Isolation

• Data monitoring• Normal behavior• Abnormal behavior (e.g., excessive collisions,

high packet loss, etc)• Set up traps (e.g., parameters in alarm group

in RMON on object identifier of interest)• Set up alarms for criticality• Manual and automatic clearing of alarms

• Problem isolation• Manual mode using network and SNMP tools• Problems in multiple components needs

tracking down the topology• Automated mode using correlation technology

Performance Statistics

• Traffic statistics• Error statistics• Used in

• QoS tracking• Performance tuning • Validation of SLA (Service Level Agreement)• Trend analysis• Facility planning• Functional accounting

Event Correlation Techniques

• Basic elements• Detection and filtering of events• Correlation of observed events using AI• Localize the source of the problem• Identify the cause of the problem

• Techniques• Rule-based reasoning• Model-based reasoning• Case-based reasoning• Codebook correlation model• State transition graph model• Finite state machine model

Rule-Based Reasoning

Rule-Based Reasoning

• Knowledge base contains expert knowledge onproblem symptoms and actions to be taken

if thencondition action

• Working memory contains topological and stateinformation of the network; recognizes system going into faulty state

• Inference engine in cooperation with knowledge base decides on the action to be taken

• Knowledge executes the action

Rule-Based Reasoning

• Rule-based paradigm is an iterative process• RBR is “brittle” if no precedence exists• An exponential growth in knowledge base poses

problem in scalability• Problem with instability

if packet loss < 10% alarm green if packet loss => 10% < 15% alarm yellow if packet loss => 15% alarm red

• Solution using fuzzy logic

Configuration for RBR Example

RBR Example

Model-Based Reasoning

Model-Based Reasoning

• Object-oriented model• Model is a representation of the component it

models• Model has attributes and relations to other

models• Relationship between objects reflected in a

similar relationship between models

MBR Event Correlator

Example:

Recognized by Hub 1 model

Hub 1 model queries router model

Hub 1 fails

Router modeldeclares failure

Hub 1 modeldeclares NO failure

Router modeldeclares nofailure

Hub 1 modeldeclares Failure

Case-Based Reasoning

Input Retrieve Adapt Process

CaseLibrary

Figure 13.12 General CBR Architecture

Case-Based Reasoning

• Unit of knowledge• RBR rule• CBR case

• CBR based on the case experienced before; extend to the current situation by adaptation

• Three adaptation schemes• Parameterized adaptation• Abstraction / re-specialization adaptation• Critic-based adaptation

CBR Parameterized Adaption

CBR: Abstraction / Re-specialization

CBR: Critic-Based Adaptation

• Human expertise introduces a new case

CBR-Based CRITTER

Codebook Correlation Model:Generic Architecture

Network Monitors

EventModel

ConfigurationModel

Correlator Problems

Codebook Correlation Model

• Yemini, et.al. proposed this model • Monitors capture alarm events• Configuration model contains the configuration

of the network• Event model represents events and their causal

relationships• Correlator correlates alarm events with event

model and determines the problem that caused the events

Codebook Approach

• Correlation algorithms based upon coding approach to event correlation

• Problem events viewed as messages generated by a system and encoded in sets of alarms

• Correlator decodes the problem messages to identify the problems

Two phases of Codebook Approaches

1. Codebook selection phase: Problems to be monitored identified and the symptoms theygenerate are associated with the problem.This generates codebook (problem-symptom

matrix)2. Correlator compares alarm events with

codebook and identifies the problem.

Causality Graph

Labeled Causality Graph

• Ps are problems and Ss are symptoms• P1 causes S1 and S2• Note directed edge from S1 to S2 removed; S2 is caused directly or indirectly (via S1) by P1• S2 could also be caused by either P2 or P3

Codebook

• Codebook is problem-symptom matrix

• It is derived from causality graph after removing directed edges of propagation of symptoms

• Number of symptoms >= number of problems

• 2 rows are adequate to identify uniquely 3 problems

Correlation Matrix

• Correlation matrix is a reduced codebook

Correlation Graph

State Transition Model

State Transition Model Example

BackboneNetwork

Router

Hub1 Hub2 Hub3

NMS / Correlator

Physical Network

State Transition Graph

Finite State Machine Model

Finite State Machine Model

• Finite state machine model is a passive system; state transition graph model is an active system

• An observer agent is present in each node and reports abnormalities, such as a Web agent

• A central system correlates events reported by the agents

• Failure is detected by a node entering an illegal state

Security Management

• Security threats• Policies and Procedures• Resources to prevent security breaches• Firewalls• Cryptography• Authentication and Authorization• Client/Server authentication system• Message transfer security• Network protection security

Security Threats

• Modification of informationModification of information: Contents modified by unauthorized user, does not include address change

• MasqueradeMasquerade: change of originating address byunauthorized user

• Message Stream ModificationMessage Stream Modification: Fragments of message altered by an unauthorized user to modify the meaning of the message

• DisclosureDisclosure• Eavesdropping• Disclosure does not require interception of message

• Denial of service and traffic analysis are not considered as threats.

Security Threats

Polices and Procedures

Secured Communication Network

• Firewall secures traffic in and out of Network A• Security breach could occur by intercepting the message going from B to A, even if B has permission to access Network A• Most systems implement authentication with user id and password• Authorization is by establishment of accounts

No Security Breaches ?

Firewalls

• Protects a network from external attacks• Controls traffic in and out of a secure network• Could be implemented in a router, gateway, or

a special host• Benefits

• Reduces risks of access to hosts• Controlled access• Eliminates annoyance to the users• Protects privacy• Hierarchical implementation of policy and

and technology

Packet Filtering Firewall

Packet Filtering• Uses protocol specific criteria at DLC, network,

and transport layers• Implemented in routers - called screening router

or packet filtering routers• Filtering parameters:

• Source and/or destination IP address• Source and/or destination TCP/UDP port

address, such as ftp port 21• Multistage screening - address and protocol• Works best when rules are simple

Application Level Gateway

DMZ(De-Militarized Zone)

Cryptography

• Secure communication requires• Integrity protection: ensuring that the message

is not tampered with• Authentication validation: ensures the originator

identification• Security threats

• Modification of information• Masquerade• Message stream modification• Disclosure

• Hardware and software solutions• Most secure communication is software based

資訊安全之重點 機密性 (Confidentiality) 真實性 (Authentication) 完整性 (Integrity) 不可否認性 (Non-repudiation) 存取控制 (Access control) 可用性 (Availability)

Dear John: I am happy to know...

Dear John: I am happy to know...

atek49ffdlffffeffdsfsfsff …

atek49ffdlffffeffdsfsfsff …

plaintext plaintext

ciphertext ciphertextencryptionencryption decryptiondecryption

Encryption

Network

Cryptography / Encryption

Encryption Encode, Scramble, or Encipher the plaintext

information to be sent. Encryption Algorithm

The method performed in encryption. Encryption Key

A stream of bits that control the encryption algorithm.

Plaintext The text which is to be encrypted.

Ciphertext the text after encryption is performed.

Encryption

Encryption Key

Dear John: I am happy to know...

Plaintext

Encryption Algorithm

atek49ffdlffffeffdsfsfsff …

Ciphertext

Decryption

Decryption Key

Dear John: I am happy to know...

Plaintext

Decryption Algorithm

atek49ffdlffffeffdsfsfsff …

Ciphertext

Encryption / Decryption

Encryption Techniques

Private Key Encryption Encryption Key == Decryption Key Also called Symmetric-Key EncryptionSymmetric-Key Encryption,

Secret-Key EncryptionSecret-Key Encryption, or Conventional Conventional Cryptography.Cryptography.

Public Key Encryption Encryption Key Decryption Key Also called Asymmetric EncryptionAsymmetric Encryption

Private Key Encryption:- DES (Data Encryption Standard)

Adopted by U.S. Federal Government. Both the sender and receiver must know

the same secret key code to encrypt and decrypt messages with DES

Operates on 64-bit blocks with a 56-bit key

DES is a fast encryption scheme and works well for bulk encryption.

Issues: How to deliver the key to the sender safely?

Symmetric Key in DES

Other Symmetric Key Encryption Other Symmetric Key Encryption Techniques Techniques

3DES Triple DES

RC2, RC4 IDEA

International Data Encryption Algorithm

Key Size Matters!

Centuries

Decades

Years

Hours 40-bits

56-bits

168-bits*Triple-DES(recommendedfor commercial& corporate information)

Info

rmat

ion

Lif

etim

e

100’s 10K 1M 10M 100MBudget ($)

Public Key Encryption: RSA

The public key is disseminated as widely as possible. The secrete key is only known by the receiver.

Named after its inventors Ron Rivest, Adi Shamir, and Leonard Adleman

RSA is well established as a de facto standard

RSA is fine for encrypting small messages

Asymmetric Key in RSA

Symmetric Cipher(Conventional)

Asymmetric (RSA/D-H)

40 Bits 274 Bits 56 Bits 384 Bits 64 Bits 512 Bits 80 Bits 1024 Bits 96 Bits 1536 Bits112 Bits 2048 Bits120 Bits 2560 Bits128 Bits 3072 Bits192 Bits 10240 Bits

Average Time for Exhaustive Key Search

32 Bits 2 = 4.3 X 10 32 9

56 Bits 2 = 7.2 X 10 56 16Number of

Possible Key128 Bits 2 = 3.4 X 10

128 38

Time required at1 Encryption/uSEC

32 Bits ==> 2 usec =36 min31

56 Bits ==> 2 usec =1142 Years55

128 Bits ==> 2 usec =5X10 Years127 24

32 Bits ==> 2 millsec

56 Bits ==> 10 Hours

128 Bits ==> 5X10 Years18

Time required at

10 Encryption/uSEC6Performance

30~200 1

Key Length

Hybrid Encryption Technology:

PGP (Pretty Good Privacy)

Hybrid Encryption Technique First compresses the plaintext. Then creates a session key, which is a one-time-

only secret key. Using the session key, apply a fast conventional

encryption algorithm to encrypt the plaintext. The session key is then encrypted to the

recipient’s public key. This public key-encrypted session key is

transmitted along with the ciphertext to the recipient.

PGP Encryption

PGP Decryption The recipient uses its private key to

recover the temporary session key Use the session key to decrypt the

conventionally-encrypted ciphertext.

PGP Decryption

Message Digest

• Message digest is a cryptographic hash algorithm added to a message

• One-way function• Analogy with CRC• If the message is tampered with the message

digest at the receiving end fails to validate• MD5 (used in SNMPv3) commonly used MD• MD5 takes a message of arbitrary length (32-Byte)

blocks and generates 128-bit message digest• SHS (Secured Hash Standard) message digest

proposed by NIST handles 264 bits and generates 160-bit output

Digital Signatures

Digital signatures enable the recipient of information to verify the authenticity of the information’s origin, and also verify that the information is intact.

Public key digital signatures provide authenticationauthentication data integritydata integrity non-repudiationnon-repudiation

Technique: public key cryptography Signature created using private key and

validated using public key

Simple Digital Signatures

Secure Digital Signatures

Authentication and Authorization

• Authentication verifies user identification• Client/server environment

• Host/User Authentication• Ticket-granting system• Authentication server system• Cryptographic authentication

• Messaging environment• e-mail• e-commerce

• Authorization grants access to information• Read, read-write, no-access• Indefinite period, finite period, one-time use

Host Authentication Allow access to a service based on a source

host identifier, e.g. network address.

Issues A host can change its network address. Different users in the same host have the same authority.

ServiceService Allow Allow

Remote Login Host-B, Host-C, 140.131.59.20File Transfer Host-A, Host-B, PC-bmw, Directory Host-C, 140.131.62.211, PC-benz… …

User Authentication Enable service to identify each user

before allowing that user access. Password Mechanism

Generally, passwords are transferred on the network without any encryption.

Use encrypted passwords. Users tend to make passwords easy to remember. If the passwords are not common words, users will write

them down.

Host Authentication ++ User Authentication

Ticket-granting system

Ticket-granting system

• Used in client/server authentication system• Kerberos developed by MIT• Steps:

• User logs on to client workstation• Login request sent to authentication server• Auth. Server checks ACL, grants encrypted ticket to

client• Client obtains from TGS service-granting ticket

and session key• Appl. Server validates ticket and session key,

and then provides service

Service

ClientWorkstation

ApplicationServer /Service

AuthenticationServer

AuthenticationUserInput

Authentication

Proxy Server

Figure 13.39 Authentication Server

Authentication Server

Authentication Server

• Architecture of Novell LAN • Authentication server does not issue ticket• Login and password not sent from client

workstation• User sends id to central authentication server• Authentication server acts as proxy agent to the

client and authenticates the user with the application server

• Process transparent to the user

Message Transfer Security

• Messaging one-way communication• Secure message needs to be authenticated

and secured• Three secure mail systems

• Privacy Enhanced Mail (PEM)• Pretty Good Privacy (PGP)• X-400: OSI specifications that define

framework; not implementation specific

Privacy Enhanced Mail• Developed by IETF (RFC 1421 - 1424)• End-to-end cryptography• Provides

• Confidentiality• Authentication• Message integrity assurance• Nonrepudiation of origin

• Data encryption key (DEK) could be secret or public key-based originator and receiver agreed upon method

• PEM processes based on cryptography and message encoding

• MIC-CLEAR (Message Integrity Code-CLEAR)• MIC-ONLY• ENCRYPTED

PEM Processes

DEK = Data Encryption DEK = Data Encryption KeyKeyIK = Interexchange KeyIK = Interexchange KeyMIC = Message Integrity MIC = Message Integrity CodeCode

Use of PGP in E-mail

SNMPv3 Security

PrivacyModule

USMauthKey

USM

AuthenticationModule

wholeMsg

Figure 13.42 SNMP Secure Communication

password

authoritativeSnmpEngineId

scopedPDU

Encryption Key

EncryptedscopedPDU

authenticatedwholeMsg

HMAC Gen.

SNMPv3 Security

• Authentication key equivalent to DEK in PEM or private key in PGP

• Authentication key generated using user password and SNMP engine id

• Authentication key may be used to encrypt message• USM prepares the whole message including

scoped PDU• HMAC, equivalent of signature in PEM and PGP,

generated using authentication key and the whole message

• Authentication module provided with authentication key and HMAC to process incoming message

Virus Attacks

• Executable programs that make copies and insert them into other programs

• Attacks hosts and routers• Attack infects boot track, compromises cpu,

floods network traffic, etc.• Prevention is by identifying the pattern of the

virus and implementing protection in virus checkers

Accounting Management

• Least developed • Usage of resources• Hidden cost of IT usage (libraries)• Functional accounting• Business application

Report Management

Policy-Based Management

Policy-Based Management

• Domain space consists of objects (alarms with attributes)

• Rule space consists of rules (if-then)• Policy Driver controls action to be taken• Distinction between policy and rule; policy

assigns responsibility and accountability• Action Space implements actions

Service Level Management

• SLA management of service equivalent to QoS of network

• SLA defines• Identification of services and characteristics• Negotiation of SLA• Deployment of agents to monitor and control• Generation of reports

• SLA characteristics• Service parameters• Service levels• Component parameters• Component-to-service mappings