iptables nmap

[distroman]

First of, what I don't know about iptables, is a lot. I know I should go read some.
Maybe someone could pass me some, easy to understand links.
As I understand it, ubuntu comes with “out of the box” iptables.

I got a question though.

I ran a nmap and I am a bit confused about the output.
Starting Nmap 4.11 ( http://www.insecure.org/nmap ) at 2006-09-11 21:56
Interesting ports on
Not shown: 65532 filtered ports
PORT STATE SERVICE
21/tcp open ftp
25/tcp open smtp
110/tcp open pop3
I can't figure out if the ftp service, is open or not, or if it's just bound to localhost.
I had a look here http://ldrolez.free.fr/secu/ but didn't make it, to clear at all.
I am really guessing, that this is not an issue at all, but I would like to know, a bit more about it.

Thanks

[Klaidas]

Well, if are nmap yourself (that is, nmap localhost or just nmap a computer which your are at now) it's ok.

[distroman]

Run with
nmap -T Aggressive -P0 -sT -r -p 1-65535
on LAN

What if per say I was on a LAN, with about 300 other boxes, would it be a problem then?
If so, how would I close these ports/services?

[steve.horsley]

I think when nmap says they're open that means they are listening for incoming connections, and they accepted the connection from nmap.

None of those ports are open on a default Ubuntu install, so I guess you have been installing servers.