Chapter 5:-SECURITY IN NETWORK

Definition
-A computing network is a computing environment with more than one independent processors
-May be multiple users per system
-Distance between computing systems is not considered (a communications media problem)
-Size of computing systems is not relevant
Network resources
*Computers
*Operating system
*Programs
*Processes
*People
Basic terminology
*Node -Single computing system in a network.
*Host -A single computing system's processor.
*Link-A connection between two hosts.
*Topology-The pattern of links in a network.
Types of Network
*Transmission technology-Broadcast networks,Point-to-point networks
*Coverage/scale-MAN,WAN,LAN
Network Topology
*Bus Topology
-To provide a single communication network on which any node can place information and from which any code can retrieve information
-Attachments to the bus do not impact the other nodes on the bus

*Star Topology
-Has a central switch
-All nodes wishing to communicate do so through the central host
-The central host receives all messages, identifies the addresses, selects the link appropriate for that addresses and forwards the messages

*Ring Topology

-To connect a sequence of nodes in a loop or ring
-Can be implemented with minimum cabling
-Containing a token can control a “synchronous” loop

*Mesh Topology
-Each node can conceptually be connected directly to each other node
-Has integrity and routing advantages
-Not easily subject to destructive failures
-Routing logic can be used to select the most efficient route through multiple nodes

LAYER

Advantages of Computing Networks

*Resource sharing -Reduces maintenance and storage costs.

*Increased reliability (i.e. availability of service) -if one system fails users can shift to another.
*Distributing the workload -Workload can be shifted from a heavily loaded system to an underutilized one.
*Expandability -System is easily expanded by adding new nodes
Who cause security problem
#Hacker
#Spy
#Student
#Businessman
#Ex-employee
#Stockbroker
#Terrorist
Network security problem area
*Authentication-Deals with determining whom you are talking to before entering into a business deal or before revealing sensitive information
*Secrecy-What usually comes to mind when people think about network security
*Non-repudiation-Deals with signature
*Integrity control-Keeping information is not modified, add or delete by unauthorized user
Threats in Networks
  **Security Exposures
*Privacy -With many unknown users on a network, concealing sensitive data becomes more difficult.
*Data Integrity -Because more nodes and more users have potential access to a computing system, the risk of data corruption is higher.
*Authenticity -It is difficult to assure the identity of a user on a remote system.
*Covert channels -Networks offer more possibilities for construction of covert channels for data flow.
NETWORKS SECURITY CONTROL

• Encryption
• Strong Authentication
• IPSec,VPN,SSH
• Kerberos
• Firewall
• Intrusion Detection System (IDS)
• Intrusion Prevention System (IPS)
• Honeypot

Hacking and prevention
*Hacker Behavior Example

1. select target using IP lookup tools
2. map network for accessible services
3. identify potentially vulnerable services
4. brute force (guess) passwords
5. install remote administration tool
6. wait for admin to log on and capture password
7. use password to access remainder of network