group2_old bridge:network protocol analysis

With this background we learnt about the usage of the protocol analyser tool wireshark.These are some of the commands whose syntaxes and functions were understood by us:-
capinfos – Prints information about capture files
dumpcap – Dump network traffic
editcap – Edit and/or translate the format of capture files
idl2wrs – CORBA IDL to Wireshark Plugin Generator
mergecap – Merges two or more capture files into one
rawshark – Dump and analyze raw libpcap data
text2pcap – Generate a capture file from an ASCII hexdump of packets
tshark – Dump and analyze network traffic
wireshark-filter – Wireshark filter syntax and reference
wireshark – Interactively dump and analyze network traffic

Group2_Old Bridge:Network protocol analysis

Network protocol analysis is a process for a program to decode network protocol headers and trailers to understand the data and information inside the packet encapsulated by the protocol. To conduct protocol analysis, packets must be captured at real time for line speed analysis or later analysis. Such program or device is called a Protocol Analyzer.

We first have to understand what is a network.
A computer network is a system in which computers are connected to share information . The connection can be done as peer-to-peer or client/server.
Peer-to-peer is a communications model in which each party has the same capabilities and either party can initiate a communication session.
On the Internet, peer-to-peer (referred to as P2P) is a type of transient Internet network that allows a group of computer users with the same networking program to connect with each other and directly access files from one another’s hard drives like the very famous

picture source-cyberpunknet.blogspot.com

Napster(www.napster.com, en.wikipedia.org/wiki/napster) & the not so famous Gnutella(en.wikipedia.org/wiki/Gnutella)
Protocol-In information technology, a protocol is the special set of rules that end points in a network connection use when they communicate.
Its very interesting how they conferred it protocol.The word protocol is derived from the Greek word protocollon, which was a leaf of paper glued to a manuscript volume, describing its contents which is very similar to the rules that are being followed for communication in a network.
The tools that are used for network protocol analysis are called as network protocol analyzers example-Ethereal (www.ethereal.com/)& wireshark(www.wireshark.org/) which can also be used on windows platform
the screenshot of ethereal on windows platform

Picture source -ethereal.com
As we can see in the picture, it analyses the protocol. Ethereal is used by network professionals around the world for troubleshooting, analysis, software and protocol development, and education.wireshark is a improved version of ethereal it can also be run on windows platform
picture source
-linuxmigration.com

Group2_Old Bridge : How LAN works

LAN: Local area network.
A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building.
There are many kinds of LAN networks such as Client-Server network in which there exists a dedicated server, peer-to-peer network in which there are no servers, but each computer works as a server.
In LAN the computers are connected through a certain medium like optical fiber or data cables which provides the pathway for electrical signals in between computers. The transmission and receiving of data is controlled by an administrator who authorizes the file access, sharing of files etc.. In LAN network, each computers are equipped with communication device called network adapter.
A network adapter interfaces a computer to a network. The term “adapter” was popularized originally by Ethernet add-in cards for PCs.
Modern network adapter hardware exists in several forms. Besides traditional PCI Ethernet cards, some network adapters are PCMCIA devices (also know as “credit card” or “PC Card” adapters) or USB devices. Some wireless network adapter gear for laptop computers are integrated circuit chips pre-installed inside the computer.
For ex: Assume two computers, say COMPUTER A and COMPUTER B are connected by a LAN newtork, Computer A contains a printer and Computer B doesn’t have printer, B will be able to access A’s printer through LAN and print the required pages from the A’s printer as if it were its own.