On Fri, Nov 6, 2009 at 5:30 AM, Craig White <craigwhite@azapple.com> wrote:

> On Fri, 2009-11-06 at 13:13 +0000, Marco Savo wrote:
> > Hello,
> > configuring iptables rules,
> > how I can find out if one port number I want to use is already in
> > use?
> > example:
> >
> > $IPTABLES -t nat -I zone_wan_prerouting 1 -j ACCEPT --protocol udp
> > --dport ${UDP_PORT}  --destination localhost
> > $IPTABLES -t nat -I zone_wan_prerouting 1 -j ACCEPT --protocol tcp
> > --dport ${TCP_PORT}  --destination localhost
> > $IPTABLES -t nat -I zone_wan_prerouting 1 -j ACCEPT --protocol tcp
> > --dport ${TCP_HOST_PORT}  --destination localhost
> >
> > How I can check if these ports (UDP_PORT TCP_PORT TCP_HOST_PORT) are
> > in use from another application?
> ----
> you can use netstat - for example, I might check for port 10000...
> # netstat -an|grep 10000
> tcp        0      0 0.0.0.0:10000     0.0.0.0:*     LISTEN
> udp        0      0 0.0.0.0:10000     0.0.0.0:*
>
> Craig
>
>
> You can also use nmap

# nmap localhost

or

# netstat -anpt

to see what is listening on what (depending on your distro - check syntax


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