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Networking & Basics.

In old article I discuss abt What is hacking , What can ethical hacker do & Step performing Crackers & Hacker ...........
In This Article we discuss the Networking i think  its useful ... & important for next level.
What is Networking ?
                     Networking is connecting devices together so that they can communicate with each other in order to share data , files & resources.
Types of Topologies.














A topology defines both the physical and logical structure of a network.
Topologies come in a variety of configurations, including:
•  Bus
•  Star
•  Ring
•  Full or partial mesh
Ethernet supports two topology types – bus and star. 

Primary type of Network.
LAN = Local Area Network  ( Small groups like home, building, School, office)
             it has higher  data transfer rates. ARCNET ,Token Rings and other technologies have been 
             used in the past. 
WAN= Wide Area Network  (Broad Area, Cross Metropolitan , National.)
             This is in Contrast with (PANs, LAN CANs MANs.)
WLAN & WWAN (Spread spectras or OFDM Radio for Mobility within local coverage Area.)

Common Network Devices.
Hub-----> Layer 1
Switch------> Layer 2
Router-------> Layer 3
Wireless Access Point ------> Layer 2 & Layer 3
Common ports & ports Number (TCP)
FTP -21-file transport protocol control.
SSH-22-ssh remote login protocol
Telnet-23
SMTP-25
HTTP-80-WWW
KERBEROS-88
POP3-110- v3
imap-143-internet message access protocol
ldap-389- Lightweight  Directory Access Protocol
https-443-HTTP over Transport Layer Security & secure socket layer
ftps-data-989- FTP over TLS &SSL
ftps-990-FTP control over TLS & SSL
telnets-992-telnet protocol over TLS &SSL
POP3s-995 -POP v3 protocol over TLS &SSL
TCP (transmission control protocol service of exchanging data)
Whereas IP handle Addressing & Routing 
IP - Internet Protocol primary Protocol used for relaying datagrams packets Source host to destination host
UDP - Unified Datagram Protocol (David P. Reed) Stripped down version of TCP No three Way Handshake, No flow control, No Sequencing, No Acknowledgement.
History of Networking 
PID - Product Identification number
MAC ID - Combination of Company ID & Product ID.
Addressing :- IP 4 bytes 32 bits numerical Label in Network that uses  Internet Protocol for combination between its nodes.
Static vs Dynamic IP
        Methods of assigning an IP address to a machine. Dynamic IP address is a different way of assigning IP address. (by DHCP) everytime ISP assign new one .
Net BIOS Name 16 Charecter alphanumeric Used in URLs to identify web pages.Net BIOS name replaced by the Domain name as they can not satisfy the global demand.
Domain Name Identification Label that defines a realm of Authority it is based on DNS Domain Name System. They organized in subordinates level (sub domains) 1st level set of domain are Top level Domains including generic TLDs below these top level domain 2nd & 3rd code top level domain.
Classes of IP
Class A= 1.0.0.1 to 126.255.255.254 Supports 16 million host on each 127 network.
Class B= 128.1.0.1 to 191.255.255.254 Supports 65000 host on each of 16000network.
Class C= 192.0.1.1 to 223.255.254.254 Support 254 host on each of 2 million network.
Class D= 254.0.0.0 to 239.255.255.255 Reserved for Multicast group.
Class E= 240.0.0.0 to 254.255.255.255 Reserved for future use or Research & Development purpose.
Internet 
           Interconected Computer Networks. (Private , Public, Buisness, Gov.) Supports www & infrastructure to support electronic mail.
Intranet 
                  Private computer network that use the standard Internal Communication and Collabaration.
DNS
        Domain Name System internet by translating human friendly.translates between domain names and IP addresses, and is supported by nearly every operating system. All Internet-based name resolution utilizes DNS.
DHCP
                  In networks with a large number of hosts, statically assigning IP addresses and other IP information quickly becomes impractical. Dynamic Host Control Protocol (DHCP)provides administrators with a mechanism to dynamicallyallocate IP addresses, rather than manually setting the address on each device.  
ARP
        Address resolution protocol  layer 3 protocol i.e network layer.ARP allows a host to determine the MAC (hardware) address for a particular IP (logical) address. 
ICMP
              Internet Control Message Protocol integral part of IP  is used for a multitude of
informational and error messaging purposes.  Several IP troubleshooting tools utilize ICMP, including Packet Internet Groper (ping)and traceroute.

 FTP
           File Transfer Protocol , copy file from one host to another over TCP/IP based Network.
   Active:- Server Assign New Port             Passive :- Client Assign New Port
Telnet
             Control information in an 8byte oriented data connection over the transmission control protocol . Because of security issue with telnet . its use for this purpose has waned in favor of SSH.
SMTP
              Simple Mail Transfer Protocol First defined by RFC 821 (STD10)in 1982 and last updated by RFC 5321 in 2008.
HTTP
                Networking Protocol for distributed hypermedia information system (www)
RFC2616 in June 1999.
POP
            Post office Protocol Retrive emails from email server.    
 
  
  

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