Chapter 13 Network Management Applications Network and Systems Management Business Management Service Management Network Management System Management Element Management Resource Management Network Elements System Resources Networked Information Systems 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 163.25.145.0 163.25.146.0 140.112.8.0 140.112.6.0 163.25.146.128 163.25.147.0 140.112.5.0 192.168.13.0 192.168.12.0 Discovery In a Network What to be discovered in a network ? Node Discovery Network Discovery The topology of networks of interest Service Discovery The network devices in each network segment The network services provided Network Topology Discovery Network 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 ipNetToMediaTable in MIB-II IP group (ARP Cache) ipNetToMediaPhysAddress ipNetToMediaType ipNetToMediaIfIndex ipNetToMediaNetAddress 1 2 00:80:43:5F:12:9A 00:80:51:F3:11:DE 163.25.147.10 dynamic(3) 163.25.147.11 dynamic(3) Network Discovery Network Discovery Key Issue: Find the networks of interest with their interconnections 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 Hub 1 Traditional LAN Configuration Port A Segment A A1 Hub 1 A2 Port A Segment A A1 Router Physical A2 Port B Segment B Router B1 Hub 2 B2 Port B Figure 13.2 LAN Segment PhysicalBConfiguration B1 Hub 2 Figure 13.2 LAN Physical Configuration A1 A2 Segment A / Hub 1 Logical A1 A2 Segment A / Hub 1 Router Segment B / Hub 2 Router B1 Segment B / Hub 2 B2 B2 Virtual LAN Configuration Hub 1 Segment A A1 Physical B1 Segment B Port A / Segment A Port A / Segment B Segment A Router Switch A2 Segment B Hub 2 B2 Figure 13.4 VLAN Physical Configuration A1 (Hub 1) A2 (Hub 2) Segment A / Hub 1 & 2 Logical Router switch Segment B / Hub 1 & 2 B1 (Hub 1) B2 (Hub 2) 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 Measurement Network Characterization Four levels defined by IETF (RFC 2063) International Backbones / National Regional / Midlevel Stub / Enterprise End-Systems / Hosts Network Flow Measurements • Three measurement entities: • Meters gather data and build tables • Meter readers collect data from meters • Managers 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 Data Level Working Memory Create new data elements Recognize Match potential rules Modify attributes of data elements Remove data elements Inference Engine Select best rule Knowledge Level Act Control Level Invoke action Knowledge Level Rule-Based Reasoning • Knowledge base contains expert knowledge on problem symptoms and actions to be taken if then condition action • Working memory contains topological and state information 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 Server D1 Backbone Router A Alarm A Router B Alarm B Hub C Alarm C Server D2 Server D3 Server D4 Alarms Dx RBR Example The correlation rule can be specified as follows: Rule 0: Alarm A : Send rootcause alarm A Rule 1 Alarm B If Alarm A present Related to A and ignore Rule 2 Alarm C If Alarm B present Related to B and ignore Rule 3 Alarm Dx if Alarm C present Related to C and ignore Correlation window: 20 seconds. Correlation window = 20 seconds Arrival of Alarm A | Alarm A sent Arrival of Alarm B | (Correlated by rule 1) Arrival of Alarm C | (Correlated by rule 2) Arrival of Alarms Dx (correlated by rule 3) End of correlation window | | Model-Based Reasoning NMS / Correlator Backbone Network Router Model Router Hub1 Hub2 Physical Network Hub3 Hub1 Model Hub2 Model Equivalent Model Hub3 Model 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: Hub 1 fails Recognized by Hub 1 model Hub 1 model queries router model Router model declares failure Hub 1 model declares NO failure Router model declares no failure Hub 1 model declares Failure Case-Based Reasoning Case Library Input Retrieve Adapt Figure 13.12 General CBR Architecture Process 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 Trouble: file_transfer_throughput=F Additional data: none Resolution: A=f(F), adjust_network_load=A Resolution status: good Figure 13.13 Matching Trouble Ticket Trouble: file_transfer_throughput=F' Additional data: none Resolution: A'=f(F'), adjust_network_load=A' Resolution status: good Figure 13.14 Parameterized Adaptation CBR: Abstraction / Re-specialization Trouble: file_transfer_throughput=F Additional data: none Resolution: A=f(F), adjust_network_load=A Resolution status: good Trouble: file_transfer_throughput=F Additional data: none Resolution: B=g(F), adjust_network_bandwidth=B Resolution status: good Trouble: file_transfer_throughput=F Additional data: adjust_network_load=no Resolution: B=g(F), adjust_network_bandwidth=B Resolution status: good CBR: Critic-Based Adaptation Trouble: file_transfer_throughput=F Additional data: network_load=N Resolution: A=f(F,N), adjust_network_load=A Resolution status: good Figure 13.16 Critic-Based Adaptation • Human expertise introduces a new case Network CBR-Based CRITTER Spectrum Configuration Management Fault Detection CRITTER Fault Management Fault Resolution Case Library Input Retrieve Determinators Adapt Application Techniques User Propose User-based Adaptation Process Codebook Correlation Model: Generic Architecture Configuration Model Event Model Correlator Network Monitors 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 they generate are associated with the problem. This generates codebook (problem-symptom matrix) 2. Correlator compares alarm events with codebook and identifies the problem. Causality Graph E4 E5 E6 E1 E2 E3 Figure 13.19 Causality Graph E7 Labeled Causality Graph S1 S2 S3 P1 P2 P3 S4 Figure 13.20 Labeled Causality for Figure 13.19 • Ps are problems and Ss areGraph 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 S1 S2 S3 S4 P1 1 1 0 0 P2 1 1 1 0 P3 0 1 1 1 • 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 S1 S3 P1 1 0 P2 1 1 P3 0 1 • Correlation matrix is a reduced codebook Correlation Graph S3 S1 P1 P2 P3 Figure 13.23 Correlation Graph for Figure 13.20 State Transition Model ping node response ping receive response Figure 13.27 State Transition Diagram for Ping / Response State Transition Model Example NMS / Correlator Backbone Network Router Hub1 Hub2 Physical Network Hub3 ping hub State Transition Graph response ping receive response No response pinged twice (Ground state) No response pinged 3 times No response Request No response from Router, No action receive response from router ping router Response Response received from Router Action: Send Alarm Finite State Machine Model Client Server Send Request Response Request Receive Response Request Message Communication Channel Response Message Receive Request Send Receive Send Response 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 information: Contents modified by unauthorized user, does not include address change • Masquerade: change of originating address by unauthorized user • Message Stream Modification: Fragments of message altered by an unauthorized user to modify the meaning of the message • Disclosure • Eavesdropping • Disclosure does not require interception of message • Denial of service and traffic analysis are not considered as threats. Security Threats Modification of information Masquerade Message stream modification Management Entity A Management Entity B Disclosure Figure 7.10 Security Threats to Management Information Polices and Procedures Basic guidelines to set up policies and procedures: 1. Identify what you are trying to protect. 2. Determine what you are trying to protect it from. 3. Determine how likely the threats are. 4. Implement measures, which will protect your assets in a cost-effective manner. 5. Review the process continuously and make improvements to each item if a weakness is found. Secured Communication Network Client A Firewall Gateway Secured Network A Client B Router Network B Server A No Security Breaches ? Figure 13.30 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 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 Trash Ethernet SMTP Gateway FTP Gateway Packet Filtering Router Screened SMTP & FTP Secured Network Figure 13.31 Packet Filtering Router Internet 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 Secured Network Firewall 1 Secured LAN Firewall 2 Proxy Services Application Gateway Figure 13.32 Application Level Gateway DMZ (De-Militarized Zone) Internet 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) Encryption Network atek49ffdlffffe ffdsfsfsff … encryption ciphertext Dear John: I am happy to know ... plaintext atek49ffdlffffe ffdsfsfsff … decryption ciphertext Dear John: I am happy to know ... plaintext Cryptography / Encryption Encryption Encryption Algorithm A stream of bits that control the encryption algorithm. Plaintext The method performed in encryption. Encryption Key Encode, Scramble, or Encipher the plaintext information to be sent. The text which is to be encrypted. Ciphertext the text after encryption is performed. Encryption Encryption Key Encryption Algorithm Ciphertext atek49ffdlffffe ffdsfsfsff … Plaintext Dear John: I am happy to know ... Decryption Decryption Key Decryption Algorithm Plaintext Dear John: I am happy to know ... Ciphertext atek49ffdlffffe ffdsfsfsff … Encryption / Decryption Encryption Techniques Private Key Encryption Encryption Key = Decryption Key Also called Symmetric-Key Encryption, Secret-Key Encryption, or Conventional Cryptography. Public Key Encryption Encryption Key Decryption Key Also called Asymmetric 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 Techniques 3DES Triple DES RC2, RC4 IDEA International Data Encryption Algorithm Key Size Matters! Information Lifetime Centuries Decades 168-bits Years 56-bits Hours 40-bits 100’s 10K 1M Budget ($) 10M 100M *Triple-DES (recommended for commercial & corporate information) 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 Key Length Average Time for Exhaustive Key Search Symmetric Cipher (Conventional) 40 56 64 80 96 112 120 128 192 Bits Bits Bits Bits Bits Bits Bits Bits Bits Asymmetric (RSA/D-H) 274 384 512 1024 1536 2048 2560 3072 10240 Performance 30~200 Bits Bits Bits Bits Bits Bits Bits Bits Bits Number of Possible Key 32 Bits 2 56 Bits 2 128 Bits 2 56 128 = 4.3 X 10 9 16 = 7.2 X 10 38 = 3.4 X 10 31 32 Bits ==> 2 usec =36 min 55 Time required at 1 Encryption/uSEC 56 Bits ==> 2 usec =1142 Years 127 128 Bits ==> 2 24 usec =5X10 Years 32 Bits ==> 2 millsec Time required at 6 10 Encryption/uSEC 1 32 56 Bits ==> 10 Hours 18 128 Bits ==> 5X10 Years 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 authentication data integrity non-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. Service Remote Login File Transfer Directory … Issues Allow Host-B, Host-C, 140.131.59.20 Host-A, Host-B, PC-bmw, Host-C, 140.131.62.211, PC-benz … A host can change its network address. Different users in the same host have the same authority. 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 Kerberos User Input Client Workstation Application Server / Service Authentication Server TicketGranting Server 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 Authentication Server User Input Client Workstation Authentication Authentication Server Proxy Server Service Application Server / Service Authentication Figure 13.39 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 DEK = Data Encryption Key IK = Interexchange Key MIC = Message Integrity Code PEM Processes SMTP Format Conversion SMTP Text MIC Generator MIC-CLEAR PEM MIC/DEK e-mail System IK DEK User Plaintext MIC Encrypted DEK Text MIC Encrypted DEK Encoded Text (a) MIC-CLEAR PEM Process MIC/DEK SMTP Format Conversion SMTP Text Encoder (Printable code) MIC Generator MIC ONLY PEM IK DEK User Plaintext e-mail System MIC Encrypted DEK (b) MIC-ONLY PEM Process Encrypted & Encoded Message MIC/DEK Legend: DEK Data Encryption Key IK Interexchange Key MIC Message Integrity Code SMTP Simple Mail Transfer Protocol MIC Generator Padding & Encryption Encoder (Printable code) (c) ENCRYPTED PEM Process ENCRYPTED PEM IK SMTP Text DEK SMTP Format Conversion DEK User Plaintext e-mail System Use of PGP in E-mail Public Key Signature Plaintext Encryption Encrypted & Compressed Message Compression Concatenation Signature Generation Private Key Plaintext e-mail conversion Figure 13.41 PGP Process e-mail system SNMPv3 Security Encrypted scopedPDU scopedPDU Encryption Key password authoritativeSnmpEngineId Privacy Module USM wholeMsg authKey USM Figure 13.42 SNMP Secure Communication HMAC Gen. Authentication Module authenticated wholeMsg 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 Table 13.1 Planning and Management Reports Category Quality of service / Service level agreement Traffic trends Technology trends Cost of Operations Reports Network availability Systems availability Problem reports Service response Customer satisfaction Traffic patterns Analysis of internal traffic volume Analysis of external traffic volume Current status Technology migration projection Functional Usage Personnel Table 13.2 System Reports Category Traffic Failures Performance Reports Traffic load - internal Traffic load - external Network failures System failures Network Servers Applications Table 13.3 User Reports Category Service level agreement User specific reports Reports Network availability System availability Traffic load Performance User-defined reports Policy-Based Management Network Attributes Policy Space Domain Space Policy Driver Rule Space Action Space 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