Nmap Basics Part 2

 Nmap Basics Part 2

Targets

Nmap can take a variety of different target ranges. CIDR notation is still supported as in 12.30.2.0/24. 

You can also specify a custom range, like 12.302.1-64. 

You can mix and match specifications, so 12.30.2.0/24 12.30.3.1-128 would be valid as well. 

You can also feed a file to nmap with a mix of IPs, ranges, and hostnames.

 Entries must be separated by spaces, tabs or newlines. I suggest the common one entry per line format for easy readability, for anyone looking at the scan and needing to see what the scope was. 

nmap has 6 built-in levels of scanning intensity, from Paranoid, -T0, to Insane, -T5. The default is -T3. Using -T4 should be acceptable if you have a good network connection between you and the target.

-T0 and -T1 are very stealthy and therefore very, very slow. Seeing most organizations don't have the bandwidth to even investigate port scanning, this level of IDS evasion probably isn't worth using. Running your scan through Tor is also usually effective unless the target has geo-blocking in place for whatever exit node you come from. -T5 is almost certain to get you noticed and unless your connection is very solid, runs the risk of dropped packets.