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nmap command

How do I install nmap command under Debian or Ubuntu Linux based system for testing security of my own network?
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nmap Command: Scan A Single IP Address or Host

How do I use nmap command to scan a single server using a host name or an IP address under Unix like operating systems?
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How do I install nmap command under CentOS / RHEL or Red Hat Enterprise Linux based system for testing security of my own network?
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How do I install nmap network security and auditing tool under OpenBSD operating system?
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How do I identify remote server os and apps using UNIX or Linux command line options?
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Q. How do I detect port scan attacks by analyzing Debian Linux firewall log files and block port scans in real time? How do I detect suspicious network traffic under Linux?
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Q. How do I check security of my network by running ICMP IP Network Scanning under FreeBSD / Linux? How do I subnet broadcast addresses? All I wanted to see if my firewall is working or not.

A. Internet Control Message Protocol (ICMP) one of the core protocols of the Internet protocol suite. It is chiefly used by networked computers' operating systems to send error messages—indicating, for instance, that a requested service is not available or that a host or router could not be reached.

ICMP IP Network Scanning with nmap tool

You can use regular open source tool called nmap. Type the following command to run ICMP IP Scan:
$ nmap -sP -PI 192.168.1.0/24
Output:

Starting Nmap 4.20 ( http://insecure.org ) at 2008-01-29 23:40 IST
Host 192.168.1.1 appears to be up.
MAC Address: 00:18:39:6A:C6:8B (Cisco-Linksys)
Host 192.168.1.106 appears to be up.
......
...
....
Nmap finished: 256 IP addresses (2 hosts up) scanned in 5.746 seconds

Where,

  • -sP : This option tells Nmap to only perform a ping scan (host discovery), then print out the available hosts that responded to the scan. This is also known as ping scan.
  • -PI : This open tells Nmap that we are sending ICMP echo requests