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Introduction xxxi
Chapter 1 Single-Area OSPFv2 Concepts 1
Objectives 1
Key Terms 1
Introduction (1.0) 3
OSPF Features and Characteristics (1.1) 3
Introduction to OSPF (1.1.1) 3
Components of OSPF (1.1.2) 4
Routing Protocol Messages 4
Data Structures 4
Algorithm 5
Link-State Operation (1.1.3) 6
1. Establish Neighbor Adjacencies 6
2. Exchange Link-State Advertisements 6
3. Build the Link-State Database 7
4. Execute the SPF Algorithm 8
5. Choose the Best Route 8
Single-Area and Multiarea OSPF (1.1.4) 9
Multiarea OSPF (1.1.5) 10
OSPFv3 (1.1.6) 12
OSPF Packets (1.2) 13
Types of OSPF Packets (1.2.2) 13
Link-State Updates (1.2.3) 14
Hello Packet (1.2.4) 15
OSPF Operation (1.3) 17
OSPF Operational States (1.3.2) 17
Establish Neighbor Adjacencies (1.3.3) 18
1. Down State to Init State 18
2. The Init State 19
3. Two-Way State 19
4. Elect the DR and BDR 20
Synchronizing OSPF Databases (1.3.4) 20
1. Decide First Router 21
2. Exchange DBDs 21
3. Send an LSR 22
The Need for a DR (1.3.5) 23
LSA Flooding with a DR (1.3.6) 24
Flooding LSAs 24
LSAs and DR 25
Summary (1.4) 27
OSPF Features and Characteristics 27
OSPF Packets 28
OSPF Operation 28
Practice 29
Check Your Understanding 29
Chapter 2 Single-Area OSPFv2 Configuration 33
Objectives 33
Key Terms 33
Introduction (2.0) 34
OSPF Router ID (2.1) 34
OSPF Reference Topology (2.1.1) 34
Router Configuration Mode for OSPF (2.1.2) 35
Router IDs (2.1.3) 36
Router ID Order of Precedence (2.1.4) 36
Configure a Loopback Interface as the Router ID (2.1.5) 37
Explicitly Configure a Router ID (2.1.6) 38
Modify a Router ID (2.1.7) 39
Point-to-Point OSPF Networks (2.2) 40
The network Command Syntax (2.2.1) 40
The Wildcard Mask (2.2.2) 41
Configure OSPF Using the network Command (2.2.4) 41
Configure OSPF Using the ip ospf Command (2.2.6) 43
Passive Interface (2.2.8) 44
Configure Passive Interfaces (2.2.9) 45
OSPF Point-to-Point Networks (2.2.11) 46
Loopbacks and Point-to-Point Networks (2.2.12) 48
Multiaccess OSPF Networks (2.3) 49
OSPF Network Types (2.3.1) 49
OSPF Designated Router (2.3.2) 49
OSPF Multiaccess Reference Topology (2.3.3) 51
Verify OSPF Router Roles (2.3.4) 52
R1 DROTHER 52
R2 BDR 53
R3 DR 53
Verify DR/BDR Adjacencies (2.3.5) 54
R1 Adjacencies 55
R2 Adjacencies 55
R3 Adjacencies 56
Default DR/BDR Election Process (2.3.6) 56
DR Failure and Recovery (2.3.7) 58
R3 Fails 58
R3 Rejoins Network 59
R4 Joins Network 59
R2 Fails 59
The ip ospf priority Command (2.3.8) 61
Configure OSPF Priority (2.3.9) 61
Modify Single-Area OSPFv2 (2.4) 63
Cisco OSPF Cost Metric (2.4.1) 63
Adjust the Reference Bandwidth (2.4.2) 64
OSPF Accumulates Costs (2.4.3) 66
Manually Set OSPF Cost Value (2.4.4) 67
Test Failover to Backup Route (2.4.5) 69
Hello Packet Intervals (2.4.7) 69
Verify Hello and Dead Intervals (2.4.8) 70
Modify OSPFv2 Intervals (2.4.9) 71
Default Route Propagation (2.5) 73
Propagate a Default Static Route in OSPFv2 (2.5.1) 74
Verify the Propagated Default Route (2.5.2) 75
Verify Single-Area OSPFv2 (2.6) 77
Verify OSPF Neighbors (2.6.1) 77
Verify OSPF Protocol Settings (2.6.2) 79
Verify OSPF Process Information (2.6.3) 80
Verify OSPF Interface Settings (2.6.4) 81
Summary (2.7) 83
OSPF Router ID 83
Point-to-Point OSPF Networks 83
OSPF Network Types 84
Modify Single-Area OSPFv2 85
Default Route Propagation 86
Verify Single-Area OSPFv2 86
Practice 87
Check Your Understanding 88
Chapter 3 Network Security Concepts 93
Objectives 93
Key Terms 93
Introduction 95
Ethical Hacking Statement (3.0.3) 95
Current State of Cybersecurity (3.1) 95
Current State of Affairs (3.1.1) 95
Vectors of Network Attacks (3.1.2) 96
Data Loss (3.1.3) 97
Threat Actors (3.2) 98
The Hacker (3.2.1) 98
Evolution of Hackers (3.2.2) 99
Cyber Criminals (3.2.3) 100
Hacktivists (3.2.4) 100
State-Sponsored Hackers (3.2.5) 100
Threat Actor Tools (3.3) 101
Introduction to Attack Tools (3.3.2) 101
Evolution of Security Tools (3.3.3) 102
Attack Types (3.3.4) 104
Malware (3.4) 106
Overview of Malware (3.4.1) 106
Viruses and Trojan Horses (3.4.2) 106
Other Types of Malware (3.4.3) 108
Common Network Attacks (3.5) 109
Overview of Network Attacks (3.5.1) 109
Reconnaissance Attacks (3.5.3) 109
Access Attacks (3.5.5) 110
Trust Exploitation Example 111
Port Redirection Example 112
Man-in-the-Middle Attack Example 112
Buffer Overflow Attack 112
Social Engineering Attacks (3.5.6) 114
DoS and DDoS Attacks (3.5.9) 115
DoS Attack 116
DDoS Attack 116
IP Vulnerabilities and Threats (3.6) 117
IPv4 and IPv6 (3.6.2) 118
ICMP Attacks (3.6.3) 118
Amplification and Reflection Attacks (3.6.5) 119
Address Spoofing Attacks (3.6.6) 120
TCP and UDP Vulnerabilities (3.7) 122
TCP Segment Header (3.7.1) 122
TCP Services (3.7.2) 123
TCP Attacks (3.7.3) 124
TCP SYN Flood Attack 124
TCP Reset Attack 125
TCP Session Hijacking 126
UDP Segment Header and Operation (3.7.4) 126
UDP Attacks (3.7.5) 127
UDP Flood Attacks 127
IP Services 127
ARP Vulnerabilities (3.8.1) 127
ARP Cache Poisoning (3.8.2) 128
ARP Request 128
ARP Reply 129
Spoofed Gratuitous ARP Replies 130
DNS Attacks (3.8.4) 131
DNS Open Resolver Attacks 131
DNS Stealth Attacks 132
DNS Domain Shadowing Attacks 132
DNS Tunneling (3.8.5) 132
DHCP (3.8.6) 133
DHCP Attacks (3.8.7) 134
1. Client Broadcasts DHCP Discovery Messages 134
2. DHCP Servers Respond with Offers 134
3. Client Accepts Rogue DHCP Request 136
4. Rogue DHCP Acknowledges the Request 136
Network Security Best Practices (3.9) 137
Confidentiality, Integrity, and Availability (3.9.1) 137
The Defense-in-Depth Approach (3.9.2) 138
Firewalls (3.9.3) 139
IPS (3.9.4) 140
Content Security Appliances (3.9.5) 141
Cisco Email Security Appliance (ESA) 142
Cisco Web Security Appliance (WSA) 142
Cryptography (3.10) 143
Securing Communications (3.10.2) 143
Data Integrity (3.10.3) 144
Hash Functions (3.10.4) 145
MD5 with 128-Bit Digest 145
SHA Hashing Algorithm 146
SHA-2 146
SHA-3 146
Origin Authentication (3.10.5) 147
HMAC Hashing Algorithm 147
Creating the HMAC Value 148
Verifying the HMAC Value 149
Cisco Router HMAC Example 149
Data Confidentiality (3.10.6) 150
Symmetric Encryption (3.10.7) 151
Asymmetric Encryption (3.10.8) 152
Diffie-Hellman (3.10.9) 155
Summary (3.11) 157
Current State of Cybersecurity 157
Threat Actors 157
Threat Actor Tools 157
Malware 157
Common Network Attacks 158
IP Vulnerabilities and Threats 158
TCP and UDP Vulnerabilities 158
IP Services 158
Network Security Best Practices 159
Cryptography 159
Practice 159
Check Your Understanding 160
Chapter 4 ACL Concepts 163
Objectives 163
Key Terms 163
Introduction (4.0) 164
Purpose of ACLs (4.1) 164
What Is an ACL? (4.1.1) 164
Packet Filtering (4.1.2) 165
ACL Operation (4.1.3) 166
Wildcard Masks in ACLs (4.2) 168
Wildcard Mask Overview (4.2.1) 168
Wildcard Mask Types (4.2.2) 169
Wildcard to Match a Host 169
Wildcard Mask to Match an IPv4 Subnet 169
Wildcard Mask to Match an IPv4 Address Range 170
Wildcard Mask Calculation (4.2.3) 170
Example 1 171
Example 2 171
Example 3 171
Example 4 172
Wildcard Mask Keywords (4.2.4) 172
Guidelines for ACL Creation (4.3) 173
Limited Number of ACLs per Interface (4.3.1) 173
ACL Best Practices (4.3.2) 174
Types of IPv4 ACLs (4.4) 175
Standard and Extended ACLs (4.4.1) 175
Numbered and Named ACLs (4.4.2) 176
Numbered ACLs 176
Named ACLs 177
Where to Place ACLs (4.4.3) 177
Standard ACL Placement Example (4.4.4) 179
Extended ACL Placement Example (4.4.5) 180
Summary (4.5) 182
Purpose of ACLs 182
Wildcard Masks 182
Guidelines for ACL Creation 183
Types of IPv4 ACLs 183
Practice 184
Check Your Understanding Questions 184
Chapter 5 ACLs for IPv4 Configuration 187
Objectives 187
Key Term 187
Introduction (5.0) 188
Configure Standard IPv4 ACLs (5.1) 188
Create an ACL (5.1.1) 188
Numbered Standard IPv4 ACL Syntax (5.1.2) 188
Named Standard IPv4 ACL Syntax (5.1.3) 189
Apply a Standard IPv4 ACL (5.1.4) 190
Numbered Standard IPv4 ACL Example (5.1.5) 191
Named Standard IPv4 ACL Example (5.1.6) 193
Modify IPv4 ACLs (5.2) 195
Two Methods to Modify an ACL (5.2.1) 196
Text Editor Method (5.2.2) 196
Sequence Numbers Method (5.2.3) 197
Modify a Named ACL Example (5.2.4) 198
ACL Statistics (5.2.5) 199
Secure VTY Ports with a Standard IPv4 ACL (5.3) 200
The access-class Command (5.3.1) 200
Secure VTY Access Example (5.3.2) 200
Verify the VTY Port Is Secured (5.3.3) 202
Configure Extended IPv4 ACLs (5.4) 203
Extended ACLs (5.4.1) 203
Numbered Extended IPv4 ACL Syntax (5.4.2) 204
Protocols and Ports (5.4.3) 206
Protocol Options 206
Port Keyword Options 207
Protocols and Port Numbers Configuration Examples (5.4.4) 208
Apply a Numbered Extended IPv4 ACL (5.4.5) 209
TCP Established Extended ACL (5.4.6) 210
Named Extended IPv4 ACL Syntax (5.4.7) 212
Named Extended IPv4 ACL Example (5.4.8) 212
Edit Extended ACLs (5.4.9) 213
Another Named Extended IPv4 ACL Example (5.4.10) 214
Verify Extended ACLs (5.4.11) 216
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