[ale] how do I close a port / security problem

[jfondow]

I just noticed that I have ports 25(smtp), 80 and 139 (NetBIOS) open and
I need to close them.  I am running a SuSE box to connect to the
internet and it is running ip-masq to serve the connection to the rest
of the house.  What do I need to do to make this machine tighter on
security.  I thought I had ip-chains configured correctly, but I must be
wrong.  Here is the url that detected the open ports: 
http://www.grc.com/default.htm.  Any and all help would be greatly
appreciated.  Thank you.

SuSE 6.2, kernel 2.2.10