crysalis is wrong...
the ports are not physically differnt.
1, P2P networks don't use secure traffic.
2, SSL communication can happen over any port as the encryption takes place in the application layer not the socket layer of the 5 layer TCP/IP implementation OSI model...
the reason that p2p services don't take place over port 80 is this is the well known port for web traffic. if P2P applications listened on this port then server aplpications wouldnt be able to listen on this port.
Also you'll find that some service providers block port 80 (incomming) to stop people from hosting personal websites.
on IIS you can set the SSL port by selecting properties (when right clicking on the website in the managment tree) and changing the port, (obviously you have to change the TCP port as well because the secure socket layer listener and the TCP listener can't both listen on the same port.
in apache you need to look at the LoadModule ssl_module modules/mod_ssl.so (uncomment) to enable SSL...
you have to tel the server to listen on another port (though it doesn't matter which one).
then in a directory section of the conf file you need to turn SSL on, then you need to turn it off when you start the non-encryted part of your website
This is in the Apache manual distributed with every compiled copy of the website...
When you go to a site
https://www.example.com the default port is used (port 443) in the same way that if you had gone to
http://www.example.com the defaul port 80 would be queried. however you have specify ports...
https://www.example.com:80
http://www.example.com:443
(clever stuff huh? you see how I switched the secure and the non-secure ports around there?)...
port 80 is popular for packet sniffers(as is ports 20 FTPcontrol, 21 FTP data, 23 TELNET, 25 SMTP because they all (usually) require some sort of password or authentification(except SMTP but that can carry sensative data) all of the proptcols for these services were made in a time when security seemed less important, and hence they all use plain text transmission, (thats right fire up a packet sniffer and you'll see all manner of things)...
No real surprises there!
Also I'm not sure about Kazza but Kaazaa Lite lets you direct traffic through a sock5 complient proxy on whatever port you like (well whatever port the proxy is running on) and also lets you send connections on port 80