If you use a wireless network, chances are good it is not secure. If you don’t make some important configuration changes on your wireless router after installing it, your wireless network is wide open to hackers, curious neighbors and people who would rather use your broadband internet service instead of buying their own.

Several of my neighbors have a wireless network set up in their home, and from my living room I can connect to three different networks in addition to my own. I do this easily, using no special skills, software or equipment. All I do is click on my wireless networking icon and select “view available wireless networks”. I choose one, click “connect”, and in an instant I am using my neighbor’s internet connection instead of my own. Kind of creepy, isn’t it?

Following are 6 things you can do to make your wireless network invisible and impenetrable to the majority of intruders.

• Change the default password of your wireless router. This makes it harder for a would-be intruder to access the router administration controls.

• Change the name of your SSID. The SSID (service set identifier) is the name of your wireless network, and by default is usually the brand name of your wireless router (like Linksys). Change this to a unique name of your choice. A good rule of thumb to follow when setting up any type of network is to always change the default settings to something else, which makes it harder for an intruder to get in.

• Use an encryption key. Most wireless routers have WEP encryption capability (Wireless Equivalent Protocol), and the newer ones also have WPA (Wi-Fi Protected Access). WEP is an older standard and less secure than WPA, so if you have both, choose WPA. Even WEP is probably good enough, and if this is all you have choose the highest bit encryption possible (usually 128 bit).

Once you set up encryption on your wireless router, write down the method you are using as well as the key (a long string of cryptic-looking characters), because you will need this to set up encryption on each of your computers that will use the wireless network.

• Disable broadcasting of your SSID. By default, the SSID (your wireless network’s name) is broadcast to anyone with a wireless network card. Although this makes it easy to configure your computers to access your network, it also makes it easy for outsiders to know about your network. By disabling SSID broadcast, no one will ever see your network.

• Limit the number of IP addresses your wireless router allows on the network. By default, your wireless router will assign an IP address to as many computers that request one. If you limit the number of addresses that the router’s DHCP server assigns to just the number that you need, you will “block” all other computers that try to connect to your network.

• Use MAC address filtering. You can configure your wireless router to only allow certain computers on the wireless network by including each computer’s MAC address in the list of “allowed” users. A MAC address is a unique physical address that is hard coded onto each network interface card. It is much like a serial number, as every MAC address is unique.

Find your network card’s MAC address by opening up a command prompt and typing in ipconfig /all. Look for something that says “physical address”, and the series of letters and numbers following this is your MAC address. It will look something like this: 00-06-5B-CE-DA-B5. Key this information into the wireless router’s MAC address filtering setup under MAC address 1. Repeat this process for every computer on your network, using MAC address 2, 3, and so on.

In addition to securing your wireless network, there is one more thing you need to do to make sure your wireless network is safe:

• Install a personal firewall on each of the computers on your wireless network. If an intruder does happen to get into your network, a personal firewall (also known as a software firewall) will keep him out of your computer. With a personal firewall running, the most an intruder can do is use your internet connection and your bandwidth; he will not be able to access your data.

What is a Spam Firewall?

A spam firewall is a hardware device that sits between your internet firewall and LAN. It is called a "firewall" because it provides data filtering of email packets, and blocks the packets that meet the criteria of "spam". Spam firewalls can also provide anti-virus protection, anti-spyware, anti-spoofing and anti-phishing services, depending on the model you choose. A spam firewall is not designed to protect your network against intruders such as hackers - you will need a regular internet firewall for that.

How Does a Spam Firewall Appliance Work?

Spam firewalls use a variety of methods for determining what is considered spam and filtering it out. Normally a form of blacklisting is used, which automatically filters out email from known spammy addresses. A whitelist may also be used, which allows the administrator to identify addresses or domains that should never be blocked. Keyword scanning may also be used, allowing the administrator or individual user to block emails containing certain keywords or keyword combinations. A form of message authenticity checking is also normally used to identify valid "from" addresses, check details of the entire SMTP process, or validate legitimate IP addresses. Many spam firewall appliances also use bayesian algorithm filtering, which help the firewall block more spam over time as it "learns" what is considered spam based on message history, user input and other analysis. Incoming message flow filters also look at the number of incoming messages and where they are from, allowing them to quickly spot and stop a sudden barrage of spam emails that have been mass-distributed from the same source. Spam firewalls are very "smart" and good at eliminating the majority of spam email that comes into a network. They are not 100% effective, but many come close.

Are Spam Firewalls Expensive?

Spam firewall appliances range in price from around $2000 up to $20,000 or more, depending on the number of users it needs to protect and features. Many spam firewalls have optional features like antivirus or anti spyware. Spam firewalls need to be kept up to date with the latest data on known spam sites, new algorithms, updated filters, etc... This is normally handled by the firewall manufacturer as an auto-update feature. As with most network appliances, an annual maintenance plan is usually purchased for the purpose of keeping the firewall up to date and performing it's best.

What About False Positives?

Spam firewall appliances use many sophisticated techniques to identify and block spam, generally with very good success. Because spammers are constantly change their techniques in order to get their junk mail past the latest and greatest spam filtering technologies, spam firewalls must continually monitor patterns and make filtering corrections. Spam firewall manufacturers are also constantly make corrective configuration changes to keep up with the battle against spammers. For this reason, even the best spam firewall is going to filter out "good" mail from time to time. This is called a "false positive", and administrators (and users) must always be on the lookout for this. Most spam firewalls have sensitivity thresholds that can be adjusted by an administrator to help overcome false positives.

A spam firewall appliance is not your typical "set it and forget it" firewall, but the advantage of having such an appliance on your network far outweighs the need for some administrative work. If your organization experiences a lot of spam mail - get a spam firewall and experience the difference!