nmap – the port scannerThis has to be the easiest port I’ve ever installed! Or is it just that I’m getting to know how to do it?
Port scanner? What’s a port scanner?A port scanner doesn’t check for software. Don’t confuse this with a FreeBSD port.
A port scanner checks the [service] ports on a host to see what services the host is willing to provide. For example, SMTP, HTTP, etc. It is a common method to find out what can be exploited on that host. Using a port scanner is a good way to find out is turned on/off for a particular host. You can also use it to help verify that your firewall restrictions are what you think they are.
Which scanner?I chose to install nmap as found in the FreeBSD Security ports. Don’t forget the nmap homepage.
The software can be downloaded from ftp://ftp.freebsd.org/pub/FreeBSD/FreeBSD-current/ports/security/nmap.tar.
The installWell, I followed the instructions found in the FreeBSD handbook for compiling ports from the internet. And it ran. First time.
To get you started, try issuing the following command:
nmap -v localhost
That should show you all the ports available on your machine.