A computer network is a group of computer that are connected to each other for the purpose of communication. Networks may be classified according to a wide variety of characteristics. A computing network is a computing environment with more than one independent processors and may be multiple users per system.
What is network can provide?
Network provided logical interface function, sending messages, receiving messages, executing program, obtaining status information and obtaining status information on other network users and their status.
Type of Network
One way to categorize the different types of computer network designs is by their scope or scale. For historical reasons, the networking industry refers to nearly every type of design as some kind of area network. Common examples of area network types are:
LAN - Local Area Network
WLAN - Wireless Local Area Network
WAN - Wide Area Network
MAN - Metropolitan Area Network
Network topologies
There are 4 topology such as Bus Topology, Star topology, Ring Topology and Mesh Topology.
IPSec
§ Authentication & encapsulation
§ Work on layer 3
§ Only can be decrypt on the receiver side
SSL
SSL is the most widely used Internet security protocol supported by all the major web browsers. SSL adds a security layer between application protocols and TCP, so applications explicitly have to ask for security. SSL specification defines a handshake protocol whereby client and server agree on a cipher suite, establish the necessary keying material and authenticate each other. Combining of symmetric (on client host)and asymmetric (on server)algorithm
Kerberos
§ 1 server use to provide control authentication called as Kerberos server
§ Host need to have a ticket before able to send a packet to any server, 1 authentication server use to control the ticket.
§ The ticket characteristic is unique, encrypted and have a life time period, since the life time is over the limit, client should request the new one before able to communicate to other server.
Firewall
A firewall prevent specific types of information from moving between the outside world and the inside world and may be separate computer system. There are four basic types of firewalls which are Packet filter, Circuit-level proxy, Stateful packet filter and Application-level proxy. The challenges in building firewalls are twofold. With respect to functionality, the protection mechanisms in the firewall have to match the customers’ security policies, which often are a mixture of address-based and identity-based policies.
IDS
§ Capture packet and compare with the rule of IDS that installed and stored in database. If detect the malicious packet, an alert will be sent to admin so an admin can go to firewall device to block that particular packet.
§ Based on attitude of admin and rule, admin must update the rule constantly so it would be still relevant.
IPS
Scan the network, and if detect a malicious packet, IPS will send alert to access list on firewall, the firewall will directly block that particular packet.
Hacking involved:
§ Reconnaissance – gain general info on target host
§ Scanning
§ Gaining access
§ Maintaining access
§ Covering track
