[nzlug] How dangerous are open ports

[Mark Foster]

Johnathan - please note I had to manually approve your message. If you 
don't post from the address you're subbed with, your mail wont likely make 
the list.



On Sun, 10 Sep 2006, Johnathan Zhuang wrote:

> Thanks for the great info guys, it was really helpful.
>
> One of the pivotal points here is that ports can be in LISTENING and/or 
> CONNECTING mode. Whereas I always thought that it was two way ALL of the 
> time.
>
> Also, netstat proved to be really useful.
>
> I was using:
>
> netstat -tupla
>
> (that's "tuple" with an a. Yeah, it's Sunday, some of us are winding down 
> :p).
>
> A question though. What's the advantage of using the -n option in the netstat 
> command. Aren't all ports numbered??
>

-n flag stops netstat from trying to do a dns resolution for any IP 
addresses that appear in the netstat output.  It might occaisionally be 
useful but more often than not it just makes the query take longer, esp 
for dns records that have to timeout before the screen will render.

Regards
Mark.