Network Administration

Hamish Whittal

Legal Notice

2005-01-25 19:35:15

Revision History
Revision 0.0.1 01/NOV/2004
Initial version

Table of Contents

1. Network Administration Fundamentals
Introducing the TCP/IP Model
The Physical Layer
The MAC Layer
The Network Layer
The Transport Layer
The Application Layer
The OSI Model
Relating the TCP and OSI Models
Overview of how the TCP/IP Model Works
A deeper look at the TCP protocol layers
Network Layer and Understanding IP addressing
Choosing the Class of network that you will use
Why use sub-netting
Summary - TCP/IP Stack
Transferring information across the Internet
Test the network with Ping
Creating and using the ARP table
Explaining routers
Briefly on LAN 's and WAN's
How to put an IP address onto your network card
Lets look at ping from the TCP/IP Stack point of view
Packets, frames, bytes, octets and datagrams
The network interfaces that you'll see if you run ifconfig -a
Setting up multiple cards in one machine
Logical and physical networks
Plumbing a device
Routing and using the "netstat" command
Further Troubleshooting with ping and arp
2. Client/Server Technology
Client / Server enhancing Performance
Client / Server enhancing Scalability
Client / Server enhancing Flexibility
Client / Server offers Interoperability
First Example:
Second example:
Central Control
Third example:
Fourth example:
Fifth example:
Client / Server implemented with RPC
3. Network Architecture
Logical versus physical network layout
Physical Network
Logical Network
The difference?
How do we connect the machines Physically
Token Ring
Understanding CSMA/CD
Maximum transmission unit (MTU)
Process that can only talk MAC address to MAC address.
Broadcasts, Unicasts and Multicasts
What is a BROADCAST?
What is a UNICAST?
What is a MULTICAST?
Why is there a distinction?
Services that are UNICAST (ssh/telnet/ftp) and broadcast (DHCP/BOOTP/ARP)
ARP and the ARP table
What is ARP?
LAN versus WAN
To define a LAN
To define a WAN
What technology must we look at when using a WAN
Hubs, switches and bridges
Routers and gateways
Broadcast versus collision domains
The concept of broadcast and collision domain
How to restrict the broadcast domain.
4. IP Address Allocation
Static IP addressing
Changing IP addresses on the fly
Plumbing a network card
Explain on-the-fly vs permanent changes (i.e. Changing Configuration files)
Dynamic Host Configuration Protocol
What is it?
Boot Protocol
How does DHCP work?
Why DHCP is restricted to a broadcast domain
Explain "dhclient"
How to obtain the address of the DHCP server
In Conclusion:
5. Basic Network Configuration
The ifconfig command
The loopback interface
Understanding the Dynamic Host Configuration Protocol (DHCP)
DHCP offers the following benefits:
6. Electronic Mail
Email follows the client/server model
Exchanging email's
Open Relays and SPAM
Retrieving email
Category 1: We are a user on the host that is also the SMTP server.
Category 2: We are a user on another host on the same Intranet as the SMTP server
Category 3: Your email resides at an ISP.
Troubleshooting email problems
Security Issues
GNU Privacy Guard (GPG)
Preamble to signing, encryption and verification
Digital signatures
Sharing your public key.
Verifying keys
The web of trust
7. Domain Naming System
What is DNS?
What do we use DNS for?
Describe the name resolution process
The host file
DNS Name Server
So where to look up the host name?
Types of records in a DNS
Forward versus reverse name resolution
Describe round robin DNS servers
Troubleshooting your DNS client configuration
Is it a DNS problem?
Ensure names resolved from the correct place
Using DIG, Why use DIG? How to use DIG? Examples
What you will need.
Using smbclient
9. Basic network troubleshooting
Reaching other devices (hosts)
Understanding PING, (responses and statistics)
Regulating the number of packets sent with PING
Response or error message
IP Address and Name resolution problems
Verifying Your Routing Table
10. Basics of network security
Firewall / Trusted and Untrusted Networks
Basic explanation - relating NAT to problems with IPv4
Checking on listening ports.
Service level security
TCP Wrappers
11. Network, System and Service Security
User security
Service level security
Configuration of tcp-wrappers
Troubleshooting TCP-wrappers
12. Network File System (NFS)
What is NFS?
How can we use NFS?
Configuring NFS
Network Information Service (NIS)
Master/Slave NIS and redundancy
Configuration of NIS clients
Where is NIS used?
To summarize NFS and NIS
Downside of NFS and NIS
13. Remote access
Inherent problems with telnet
Public and Private Key Infrastructure
Sample Session for Generating a key
Sample Session for Accepting a fingerprint
Sample Session for Verifying a fingerprint
Sample Session Using ssh agent
Sample Session to destroy your public/private key pair
14. Connecting remotely to the X Window System
So here we are:
Some practice
15. Connecting to an ISP
Before we begin:
A. Practical lab

List of Figures

1.1. The OSI Model

List of Tables

1.1. TCP/IP Protocols and some of the related services