nmap – the port scanner
This 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
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.
software can be downloaded from ftp://ftp.freebsd.org/pub/FreeBSD/FreeBSD-current/ports/security/nmap.tar.
To get you started, try issuing
the following command:
nmap -v localhost
That should show you all the ports available on your machine.