Without any description of your connection, I assume that you’re a home user with either a DSL or Cable modem connection to the Internet. You could possibly have a wireless connection as well.
In order to protect yourself in that type of environment, you’re going to need a firewall. You could choose a setup containing any of the following components, either in combination or by themselves:
1) Purchase a cable router that contains a firewall/IDS
2) Install a software firewall on your computers
3) Use WEP/WPA encrytption on your wireless and change the unsecure default passwords and settings.
4) Possibly use a VPN on your wireless clients, firewall the wireless router
I like the SMC Barricade Cable Router as it has a firewall, IDS, DMZ, DHCP server, and a lot of other features. There are others like Linksys, D-Link, and Netgear that are all about the same price range $40-$80.
Use a personnal firewall like ZoneAlarm on your PCs. Enable windows firewall. Don’t allow anyone to connect to your PC that you don’t want there.
Read the documentation on your wireless router and don’t do run any wizards on them. Go into the router yourself and choose the most secure options. I’m almost willing to say: “Don’t do anything that the dcumentation says…” but that’s because I read what my Linksys docs said and shivered by how insecure it would be if I did that (no encryption or changing of any defaults).
For setting up a VPN, you’ll need either a router capable of it or to setup a PC with VPN software. I’m sure there’s Free Windows VPN software out there, but it’s like putting a lock on a celephane bag. You’d probably do better finding something prepackaged because it’s the most ifficult of these to set up.
Oh… NEVER let anyone see tcp port 139 or it’s “game over.”
Good Luck. You should reload your PC now, but get a firewall in place first or you’ll be owned again.