1. Process Model
(Disadvantage)

1. Process Model
(Bild)

2. Thread Model
(Use threads instead of processes)
(Motivation)

2. Thread Model
(Use threads instead of processes)
(Problem)

2. Thread Model
(Advantages)

2. Thread Model
(Disadvantages)

3. In-kernel Model

3. In-kernel Model
(One option)

3. In-kernel Model
(Most often)

3. In-kernel Model
(Advantages)

3. In-kernel Model
(Disadvantages)

3. In-kernel Model
(Examples)

4. Event-driven Model
(1)

4. Event-driven Model
(2)

4. Event-driven Model
(Advantages)

4. Event-driven Model
(Disadvantages)

Performance Comparison

Web Server Cluster
(Two ways of increasing capacity)

Web Server Clusters
(Latter approach currently dominating)

Web Server Clusters
(Typical architecture)

Web Server Clusters

FTP: The File Transfer Protocol

FTP: Separate Control & Data Connections

FTP Commands, Responses
(Sample commands)

FTP Commands, Responses
(Sample return codes)

Electronic Mail
(Three major components)

Electronic Mail
(User Agent)

Electronic Mail
(Bild)

Electronic Mail: Mail Servers
(Mailservers)
(Mailbox)

Electronic Mail: Mail Servers
(Mailservers)
(Message queue)

Electronic Mail: Mail Servers
(Mailservers)
(SMTP protocol)

Electronic Mail: Mail Servers
(Bild)

Electronic Mail: SMTP [RFC 2821]

Scenario: Alice Sends Message to Bob

Sample SMTP interaction

Try SMTP Interaction for Yourself

SMTP: Final Words

Mail Message Format

Message Format: Multimedia Extensions

Mail Access Protocols
(SMTP)

Mail Access Protocols
(Mail access protocol)

Mail Access Protocol
(Bild)

POP3 Protocol

POP3 and IMAP
(More about POP3)

POP3 and IMAP
(IMAP

DNS: Domain Name System
(People)

DNS: Domain Name System
(Internet hosts, routers)

DNS: Domain Name System
(Domain Name System)
(Distributed database)

DNS: Domain Name System
(Domain Name System)
(Application-layer protocol)

DNS
(DNS services)

DNS
(Why not centralize DNS?)

Distributed, Hierarchical Database

DNS: Root Name Servers

DNS: Root Name Servers
(Root name server)

TLD, Authoritative and Local DNS Servers
(Top-level domain (TLD) servers)

TLD, Authoritative and Local DNS Server
(Authoritative DNS servers)

TLD, Authoritative and Local DNS Server
(Local DNS servers)

Iterative Queries: Example
(Bild)

Iterative Queries: Example
(Iterated query)

Recursive Queries: Example
(Bild)

Recursive Queries: Example
(Recursive query)

DNS: Caching and Updating Records

DNS Records

DNS Protocol, Messages
(DNS protocol)

DNS Protocol, Messages
(Bild - 1)

DNS Protocol, Messages
(Bild - 2)

Inserting Records Into DNS

P2P File Sharing

P2P: Centralized Directory

P2P: Centralized Directory
(Bild)

P2P: Problems With Centralized Directory

Query Flooding: Gnutella
(General Properties)

Query Flooding: Gnutella
(Overlay network: graph)

Gnutella: Protocol

Gnutella: Peer Joing

Socket Programming
(Goal)

Socket Programming
(Socket API)

Socket Programming
(Socket)

Socket-Programming Using TCP
(Socket)

Socket-Programming Using TCP
(TCP service)

Socket-Programming Using TCP
(Bild)

Socket Programming With TCP
(Client must contact server)

Socket Programming With TCP
(Client contacts server by)

Socket Programming With TCP

Socket Programming With TCP
(application viewpoint)

Stream Jargon
(Stream)

Stream Jargon
(Input Stream)

Stream Jargon
(Output Stream)

Socket Programming With TCP
(Example Client-Server application)

Socket Programming With TCP
(Bild)

Client/Server Socket Interaction: TCP

Example: Java Client (TCP)
(1)

Example: Java Client (TCP)
(2)

Example: Java Server (TCP)
(1)

Example: Java Server (TCP)
(2)

Socket Programming With UDP

Socket Programming With UDP
(Application viewpoint)

Client/Server Socket Interaction: UDP

Example: Java Client (UDP)

Example: Java Client (UDP)

Example: Java Client (UDP)

Example: Java Sender (UDP)
(1)

Example: Java Server (UDP)
(2)

Building a Simple Web Server

Chapter 1: Summary
(1)

Chapter 1: Summary
(2)

Appendix: Socket Programming with C

Example: C Client (TCP)
(1)

Example: C Client (TCP)
(2)

Example: C Client (TCP)
(1)

Example: C Server (TCP)
(2)

Example: C Client (UDP)
(1)

Example: C Client (UDP)
(2)

Example: C Server (UDP)
(1)

Example: C Server (UDP)
(2)

What is a Threat in a Communication Network
(Abstract Definition)

What is a Threat in a Communication Network?
(Examples)

What is a Threat in a Communication Network?
(What are security goals)

Security goals depending on the application environment 1
(Banking)

Security goals depending on the application environment 1
(Electronic trading)

Security goals depending on the application environment 1
(Government)

Security goals depending on the application environment 2
(Public Telecommunication Providers)

Security goals depending on the application environment 2
(Corporate / Private Networks)

Security goals depending on the application environment 2
(All Networks)

Security goal depending on the application environment

Security Goals Technically Defined
(Confidentiality)

Security Goals Technically Defined
(Data Integrity)

Security Goals Technically Defined
(Accountability)

Security Goals Technically Defined
(Controlled Access)

Threats Technically Defined
(Masquerade)

Threats Technically Defined
(Eavesdropping)

Threats Technically Defined
(Authorization Violation)

Threats Technically Defined
(Loss or Modification of (transmitted) Information)

Threats Technically Defined
(Denial of Communication Acts (Repudiation))

Threats Technically Defined
(Forgery of Information)

Threats Technically Defined
(Sabotage)

Threats and Technical Security Goals

Security Analysis of Layered Protocol Architectures 1

Security Analysis of Layered Protocol Architectures 2

Attacking Communications on the Message Level
(Passive attacks)

Attacking Communications on the Message Level
(Active attacks)

Attacking Communications on the Message Level
(Successful launch of one of the above attacks requires)

Attacking Communications on the Message Level

Safeguards Against Information Security Threats 1
(Physical Security)

Safeguards Against Information Security Threats 1
(Personnel Security)

Safeguards Against Information Security Threats 1
(Administrative Security)

Safeguards Against Information Security Threats 1
(Emanations Security)

Safeguards Against Information Security Threats 2
(Media Security)

Safeguards Against Information Security Threats 2
(Lifecycle Controls)

Safeguards Against Information Security Threats 2
(Computer Security)

Safeguards Against Information Security Threats 2
(Communications Security)

Communications Security: Some Terminology
(Security Service)

Communications Security: Some Terminology
(Cryptographic Algorithm)

Communications Security: Some Terminology
(Cryptographic Protocol)

Security Services - Overview
(Authentication)

Security Services - Overview
(Integrity)

Security Services - Overview
(Confidentiality)

Security Services - Overview
(Access Control)

Security Services - Overview
(Non-Repudiation)

Cryptology - Definition and Terminology
(Cryptology)

Cryptology - Definition and Terminology
(Cryptology)
(Cryptology encompasses)
(Cryptography (graphein = to write))

Cryptology - Definition and Terminology
(Cryptology)
(Cryptology encompasses)
(Cryptoanalysis (analyein = to loosen, to untie))

Cryptology - Definition and Terminology
(Cipher)

Cryptographic Algorithms
(Encryption of data)

Cryptographic Algorithms
(Signing of data)

Cryptographic Algorithms

Cryptographic Algorithms
(Symmetric cryptography)

Cryptographic Algorithms
(Asymmetric cryptography)

Cryptographic Algorithms
(Cryptographic hash functions)

Important Properties of Encryption Algorithms

Symmetric Encryption

Asymmetric Cryptography
(General idea)

Asymmetric Cryptography
(Applications)
(Encryption)

Asymmetric Cryptography
(Applications)
(Signing)

Asymmetric Cryptography
(Applications)
(Attention)

Asymmetric Cryptography
(Practical considerations)

Detection of Message Modifications
(Motivation)

Detection of Message Modifications
(Realization of modification check values)
(Cryptographic Hash Functions)

Detection of Message Modifications
(Realization of modification check values)
(Message Authentication Codes)

Cryptographic Protocols
(Definition)

Cryptographic Protocols
(Applications of cryptographic protocols)

Cryptographic Protocols
(Applications of cryptographic protocols)
(Authentication)
(Data origin authentication)

Cryptographic Protocols
(Applications of cryptographic protocols)
(Authentication)
(Entity authentication)

Security in Networks: What to do where?

Security in Networks: What to do where?
(Bild)

A Pragmatic Model for Secured & Networked Computing

A Pragmatic Model for Secured & Networked Computing
(Application)

A Pragmatic Model for Secured & Networked Computing
(End System)

A Pragmatic Model for Secured & Networked Computing
(Subnetwork)

A Pragmatic Model for Secured & Networked Computing
(Inter-Network)

A Pragmatic Model for Secured & Networked Computing

A Pragmatic Model for Secured & Networked Computing
(Application level)

A Pragmatic Model for Secured & Networked Computing
(End system level)

A Pragmatic Model for Secured & Networked Computing
(Subnetwork level)

A Pragmatic Model for Secured & Networked Computing
(Link level)

Relationships Between Layers & Requirements Levels

Relationships Between Layers & Requirements Levels
(Bild)

Security Problems of the Internet Protocol
(When an entity receives an IP packet, it has no assurance of)
(Data origin authentication/data integrity)

Security Problems of the Internet Protocol
(When an entity receives an IP packet, it has no assurance of)
(Confidentiality)

Security Objectives of IPSec
(IPSec aims to ensure the following security objectives)
(Data origin authentication/connectionless data integrity)