i wounder how i close ports in slackware 7.1

There is no reason to close a port is nothing is responding to it! you can disable services in /etc/inetd.conf file Other you can definitly block a specific port with ipchain!! type: man ipchain for more info,

iptables -A INPUT -p tcp --dport 80 -j drop That is the iptables command to drop all tcp packets destined for port 80. iptables requires a 2.4.X kernel with correct options compiled.

Referencing Danny: A port is opened when you have a service running. It doesn't necessarily matter what OS you're running, but a port doesn't open up unless an application is running (in the background)to use the port. For example: Apache running in the background responding to http requests on Port 80 (standard). If there's nothing there to respond to the requests of port 80, portt 80 isn't opened. Also, take a look at your /etc/services file. That'll also give you a good idea of what ports are defined.