Figure 1-7: Eavesdropping on a Dialog Hello Client PC Bob Server Alice Hello Attacker (Eve) intercepts and reads messages

Figure 1-8: Encryption for Confidentiality Encrypted Message “100100110001” Client PC Bob Server Alice “100100110001” Attacker (Eve) intercepts but cannot read Original Message “Hello” Decrypted Message “Hello”

Figure 1-9: Impersonation and Authentication I’m Bob Client PC Bob Prove it! (Authenticate Yourself) Attacker (Eve) Server Alice

Figure 1-10: Message Alteration Dialog Client PC Bob Balance = $1,000,000 Balance = $1 Server Alice Balance = $1 Balance = $1,000,000 Attacker (Eve) intercepts and alters messages

Figure 1-11: Secure Dialog System Client PC Bob Server Alice Automatically Handles Negation of Security Options Authentication Encryption Integrity Attacker cannot read messages, alter messages, or impersonate

Figure 1-12: Network Penetration Attacks and Firewalls Passed Packet Attack Packet Internet Firewall Hardened Client PC Internet Attacker Hardened Server Dropped Packet Internal Corporate Network Log File

Figure 1-13: Scanning (Probing) Attacks I’m Here Attack Packets to 172.16.99.1, 172.16.99.2, etc. Host 172.16.99.1 Internet Attacker Host 172.16.99.2 I’m Here Corporate Network

Figure 1-14: Single-Message Break-In Attack 1. Single Break-In Packet 2. Server Taken Over By Single Message Attacker

Figure 1-15: Denial-of-Service (DoS) Flooding Attack Message Flood Server Overloaded By Message Flood Attacker

Figure 1-16: Intrusion Detection System (IDS) 1. Suspicious Packet Intrusion Detection System (IDS) 4. Alarm Network Administrator 2. Suspicious Packet Passed Internet Attacker Hardened Server 3. Log Suspicious Packet Corporate Network Log File