Internet security question

[AmigaMance]

 I have an Amiga 1200. I go online using miami and a 56k modem without a firewall etc.
Lets say that using the "MiamiNetStat -a" command i find out that i have an unwanted open port. How do i close this port? I know that i can log-out, enter the miami preferences and block out the IP, but how can i do it on-the-fly?
 Also, how can i tell that someone is scanning my ports?

[AmigaMance]

@mr_a500
 Yeap, i'm using these settings ;-)

@piru

 Lets say that using the "MiamiNetStat -a" command i find out that i have an unwanted open port. How do i close this port?

 Disable the service(s) from the Network Database, Services page.

This can be done without the need to log-out and redial? and what if i need these services? I assume that there is no simple way to just close that port?

[AmigaMance]

 @Piru
 Ok, thanks.
It's disable the service, click "Ok" and select "save" or "save as default" from the 2nd menu. :-)