Nmap Development mailing list archives
Re: Documentation issue (-F)
From: David Fifield <david () bamsoftware com>
Date: Thu, 12 Apr 2012 14:29:14 -0700
On Thu, Apr 12, 2012 at 01:09:50PM -0500, Daniel Miller wrote:
List, From the man page:-F (Fast (limited port) scan) . Specifies that you wish to scan fewer ports than the default. Normally Nmap scans the most common 1,000 ports for each scanned protocol. With -F, this is reduced to 100. Nmap needs an nmap-services file with frequency information in order to know which ports are the most common. If port frequency information isn't available, perhaps because of the use of a custom nmap-services file, -F means to scan only ports that are named in the services file (normally Nmap scans all named ports plus ports 1–1024).Empirically, I see Nmap scans 1000 ports by default, 100 with -F, and <300 when nmap-services is not available. What is that last parenthetical statement about? Is this old info which should be purged?
This is not what I see. When I delete nmap-services from everywhere it might be found: $ ./nmap -d3 localhost | egrep -c '^[0-9]+/tcp' Unable to find nmap-services! Resorting to /etc/services Port 2010 proto tcp is duplicated in services file /etc/services Port 2121 proto tcp is duplicated in services file /etc/services 1200 $ ./nmap -d2 localhost -F | egrep -c '^[0-9]+/tcp' Unable to find nmap-services! Resorting to /etc/services Port 2010 proto tcp is duplicated in services file /etc/services Port 2121 proto tcp is duplicated in services file /etc/services 313 If you are using "--servicedb /etc/services", --servicedb implies -F, so you would only see the smaller number. The part about "all named ports plus ports 1-1024" is this code in services.cc: getpts("1-1024,[1025-]", ports); David Fifield _______________________________________________ Sent through the nmap-dev mailing list http://cgi.insecure.org/mailman/listinfo/nmap-dev Archived at http://seclists.org/nmap-dev/
Current thread:
- Documentation issue (-F) Daniel Miller (Apr 12)
- Re: Documentation issue (-F) David Fifield (Apr 12)
- Re: Documentation issue (-F) Daniel Miller (Apr 12)
- Re: Documentation issue (-F) Fyodor (Apr 13)
- Re: Documentation issue (-F) Daniel Miller (Apr 12)
- Re: Documentation issue (-F) David Fifield (Apr 12)