Internet Technology Basics

Clients and Servers
  • Both are computers, depends on their purpose
  • Networking’s purpose is to get ‘data’ from one to the other
  • …. even when they are on the other side of the world
Take a look at
$ ping brandeis.edu
$ traceroute mit.edu
Basic Terms
  • Host: Internet-ese for a computer that is part of the network
  • MAC addres: A totally unique number assigned at time of manufacture to every piece of hardware that can be connected to the network. Media Access Control address. It “cannot” be changed.
  • IP Address: Internet Protocol Address, e.g. 12.44.23.123
  • Domain name: A name assigned to a host on the internet, e.g. brandeis.edu
  • DNS: Domain Name System. An internet-wide service (a distributed database) that associates ip addresses to domain names
MAC addresses, IP addresses and DNS
  • User types in a domain name
  • Target computer is identified by an IP address
  • So: Need a phonebook of some kind
  • DNS: distributed name service

Basic Network utility programs

  • ping: sends a message to a destination host and listens that the packet is sent back
  • traceroute: similar, but records the intervening hosts
  • ifconfig: list network interfaces and what IP address they are associated with
  • netstat: A really verbose printout of all the local TCP/IP ports and whats going on
  • nslookup: Look up the ip address of a domain name
  • whois: lookup what the internet knows about the owner of a certain domain name Reference: 8 Unix Networking Commands
More about IP
  • So the IP address is for 1 specific ‘host’ or server (as usual there are exceptions :)
  • IP is the way servers talk ‘to each other’ to get a packet of bits between them
  • Conceptually, ‘send these bits to this ip address’
  • What’s a port number
  • TCP/IP: what it means