I've noticed that nmap only scans a bunch of known ports, and the only way i've managed to check 'em all is to put a "-p 0-65535" in.
Why is that? am I wrong? is there a more popular way to scan all ports aside from what I've done?
By default, Nmap scans the top 1000 most popular ports, according to the statistics generated from Internet-wide scans and large internal network scans from the summer of 2008. There are a few options that change this:
These numbers were set in version 4.75, and were a change from the roughly 1700 (TCP) ports that were the default in version 4.68. The purpose was to decrease scanning times while still giving reasonable results. The flexibility of Nmap's command-line options guarantees that you can still scan just about any combination of ports that you want, regardless of the defaults.
Scanning all 65536 TCP ports is still possible with
Well if you don't want to put the port range you can always just give the
argument, which will scan, by default, all the ports, except port 0. For port 0, you have to explicitly specify it.