‫You can scan the network to find out the computer systems and network and discover the network topology.
‫First, let's see the scan types.
‫There are two types of scanning, first type is passive scan.
‫In this type of scanning, you don't want to be recognized by the target.
‫In this regard, you don't directly contact target systems just by watching the network's traffic flow,
‫passive scanners can deduce a large amount of information about the communicating systems.
‫You can use tools such as TCP Dump or Wireshark to monitor network traffic, looking at the ARP table
‫in a computer which is connected to the network is another example of passive scanning.
‫So the second type is active scan in this type of scanning, you scan on the target systems.
‫Active scanning requires more preparation for the attacker or pin tester because it leaves traces which
‫are likely to alert the target or produce evidence against him.
‫Active scanning on your network can also return great headaches, however.
‫It can have a high political cost and far reaching effects on system uptime and reliability, if not
‫done carefully, it can be an ineffective, inefficient way to gather information.
‫We'll see and map in details.
‫H Ping is an excellent command line oriented TCP IP packet analyzer, it looks like ping command, but
‫each ping isn't only able to send ICMP Echo request.
‫It supports TCP, UDP, ICMP and raw IP protocols as a traceroute mode, the ability to send files between
‫a covered channel and many other features.
‫Skype is a powerful interactive packett manipulation program.
‫It is able to forge or decode packets of a wide number of protocols, send them on the wire, capture
‫them, match requests and replies and much more.
‫Traceroute is a utility that records the route, the specific Gateway computers at each hop through
‫the network between your computer and a specified destination computer so you can find out the network
‫devices between you and the target and identify the network topology.
‫There's a really good comparison of active and passive scanning on network world dot com website, which
‫says just as you can determine the type of cheese by tasting it an active scan, you can also use passive
‫techniques such as reading the label or smelling the aroma as it passes by.