Firewalls: Your First Line of Defense
What Does a Firewall Do?
Simply stated, a firewall is a software or hardware product that screens the information coming into and leaving your computer to ensure that there is no unauthorized access to your computer.
Home routers from 10 manufacturers, including Linksys, DLink, and Belkin, can be turned into covert listening posts that allow the Central Intelligence Agency to monitor and manipulate incoming and outgoing traffic and infect connected devices. — Ars Technica
Firewalls provide your first line of defense and can help you control what accesses and leaves your computer.
Without a firewall, your computer is operating with an 'open door' policy. Bank account information, passwords, credit card numbers, virtually any sensitive information on your computer becomes available to hackers. Hackers can get in, take what they want, and even leave one of their own 'back doors' in place for ongoing access to your computer whenever they like. — ZoneAlarm
Two Types of Firewalls
There are two basic types of computer firewalls:
- Routers are a hardware firewall that provides the first line of defense.
- Software firewalls are a security program on your computer.
Both monitor and control access to the Internet and to your network (if you have one) for programs and components on your computer.
You NEED a Firewall
If you are continually connected to the Internet you cannot afford to be without a firewall.
This includes those using ADSL or a cable modems or connecting through a network. But be sure that your firewall is actually protecting you.
We're More Connected Than Ever
Most software today wants to "call home" using the Internet for various reasons:
- Many help files are no longer located on your computer.
- Many hardware devices install news or update programs along with the drivers necessary to make them work.
- Media programs such as RealPlayer or Windows Media Player want to offer live media feeds, to retrieve album art and more.
Can You Trust What is Being Sent?
Can you trust the information they are sending? Perhaps not.
A decent software firewall, when configured properly, allows you to control what software and components have access.
Routers — Your Hardware Firewall
A router serves as a hardware firewall and provides the first line of protection by hiding your computer(s) from those trying to gain unauthorized access. A router provides secure shared access to high-speed Internet services for all your computers and allows you to share information across the network if you wish.
There are other hardware firewalls, but they are beyond the scope of this page (and seldom used by home or small business users).
Buying a Router
Most units sold today have four wired outputs and can support up to 253 additional computers via the wireless connection. More expensive routers can provide more options like blocking or allowing certain sites or turning the access to the Internet off when you're not usually home.
Secure Your Wireless Router
Because wireless routers are available to anyone within range, you need to take special precautions:
- Standard (non-wireless) routers provide connections only to computers physically connected to the router via a network cable.
- Wireless routers provide connections both via network cable and via wireless (radio) connections.
Wireless routers should be secured using encryption. What is available to you depends upon both the age of the router and the computers that connect to that router.
The most commonly used encryptionare WPA and WPA2.
Avoid Obsolete Security Protocols
WEP is now obsolete and provides poor security so it should not be used even if it is available.
If you are using a new router but have an old laptop you will be unable to use the most recent (and most secure) methods of encryption unless you purchase a suitable external wireless device or upgrade your computer. Disable wireless connections or dispose of devices capable of only WEP encryption.
Turn Off WPS
My recommendation is to diable WPS using router's browser-based configuration tools.
Here's the settings on a D-Link router. Your configuration may differ.
This varies by router, but these are the basic steps:
- Log into your router using the network address (usually something like
http://192.168.0.1/) with the user name and password.
- Navigate to the WiFi Protected Setup (probably under Advanced settings).
- Ensure that WPS Enable is unchecked (or otherwise disabled).
- Save the settings then log out of the router settings.
Firefox indicated a potential security risk because this D-Link router doesn't support the HTTPS protocol.
Change the Router's Defaults
You should never use the default settings for your wireless router as these standards are well known and easily searched out on the Internet.
- First, change the user name and password used to log into the configuration screen to secure your router.
- Next, change the SSID to something meaningful to you that won't identify the router's make. More about choosing SSIDs and passwords.
- Be sure to select the most secure protocol (WPA or WPA2).
- If older devices are unable to use WPA or WPA2 protocols, replace them. Downgrading your security can make your entire network vulnerable.
There is more detailed information about wireless security on Wikipedia.
Router Recommended with Shaw or Telus Provided Router/Modems
I recommend using a router in addition to the units provided by Shaw or Telus, but this is trickier.
Changes Needed for Shaw Cable Customers
Shaw (as well as Rogers and other cable companies) can block your computer's access to Shaw services like email and other customer-only services once your computer is behind a router.
- Shaw customers should use mail.shaw.ca for their email server name. Outgoing sever settings are different for home use and mobile devices.
- See Shaw's Mail Server Names for additional information.
- Customers of other cable companies should check with their ISP for details.
Changes Needed for Telus Customers
Unfortunately some recent equipment provided by Telus has made it more difficult to use your own router, especially if you also subscribe to Telus TV.
- Log into the Telus router and navigate to the Advanced Wireless Configuration settings using a network cable.
- Look for the option to bridge the connection then save the settings.
- Connect your router to the Telus router's Port 1 (NOT the WAN port).
- Now turn off and restart both your Telus and other router.
- Connect your computer to the third-party router. You may need to restart your computer or refresh your network settings.
Bridging sends the raw IP addresses coming in directly to your DHCP-enabled router rather than allowing the Telus router to manage traffic . You'll probably need to reboot your router (and possibly your computer) to see the new network.
The following may help with this process:
- Bridge Mode - Using Your Own Router on the Telus forum.
- How to hook up my existing Wireless N router with a Telus modem may help but didn't match the configuration of my current Telus router.
These are some of the common manufacturers of routers:
The reliability of these routers varies and you should do some research before purchasing a new router. For example, there are security vulnerbilities in D-Link products that contributed significantly to botnet attacks:
I think the FTC was feeling the heat from the botnet attacks, of which we believe there were a lot of D-Link devices included. And let me be clear, D-Link is absolutely at fault for a lot of this. Some of the most basic vulnerabilities have existed in their products for over 10 years that they haven't patched. And that's a pretty — yeah, that's bad. But as you mentioned, it's not illegal to make a bad product. — Security Now! Transcript of Episode #630.
Update Your Firmware
If you are having trouble with a router, check the manufacturer's site for firmware updates specific to your router (check for FAQs, firmware and other information under Support).
Be sure that you are selecting the right version for firmware as similarly-named models vary between countries as well as versions. An improperly updated device may cease to work.
D-Link Router Security Issue
A security vulnerability was reported for several routers including some of D-Link's product line where there is a secret code that bypasses the router's security. Not all D-Link routers are affected and updating the firmware can be somewhat tricky so you might want to review the videos on D-Link's site for the warnings and help.
- Story: D-Link Routers Vulnerable to 'Backdoor' Exploit.
- D-Link (UK) list of affected router models.
- I was unable to locate this information on the Canadian D-Link site but care should be taken to download updates only on the Canadian site for your model if it is affected.
- My clients may wish to contact me if they are concerned. Others should contact their own support or hire me.
These resources can help to explain some of these issues in greater detail:
- Practically Networked Hardware Router Product Guide.
- Firewall Router Reviews compares several brands and models.
- FAQ: Firewall Forensics (What am I seeing?) helps to explain firewall terms and what your logs are telling you.
Back Up Your Router with a Software Firewall
Software firewalls and routers are each more adept at different, but complimentary, tasks.
What Firewall Programs Do
A firewall program verifies whether software programs and components are allowed access to the Internet and then enforces it by either allowing or denying access.
A software firewall is an essential part of your protection, particularly if your Internet access is through a broadband connection (which includes virtually everyone these days).
As programs are both sending information and receiving information or installing software, be sure your software firewall is effective and that it protects you from outgoing as well as incoming attacks.
Many Choices — Not All Effective
You can purchase several firewall software packages in retail stores and download and purchase others on-line but the effectiveness of these products varies.
Firewall Quality Varies
Gibson Research Corporation's evaluations are quite dated, but will provide you with a better understanding of the many variables that must be considered in designing a good firewall.
Windows Firewall Inadequate
Windows users should not depend upon the Internet Connection Firewall that comes with Windows since it offers limited outbound protection.
Microsoft's detection of malware and spyware has improved but most third-party security solutions provide better protection.
Mac OS X's firewall, like its Windows counterpart, provides only inbound protection. There is no outbound protection and provides no additional protection if you're behind a router.
Connection Problems May Be Firewall Issues
Programs that are unable to access the Internet may be having difficulty with your firewall. These articles (all related to issues with Firefox access to the Internet) may help you to deal with access issues when using other programs as well:
- This MozillaZine article on firewalls deals with various firewalls and how they can stop programs from accessing the Internet. Sometimes you may not know that a firewall is running or it may be misconfigured.
- The top 12 ways to get fooled by firewalls is an interesting list of potential problems with various firewalls.
Avoiding Security Breaches
You should know how to configure the software properly to avoid a security breach.
- Ensure that your firewall is not circumvented by someone with physical access to your computer.
- Don't automatically give permission to any program requesting access — most setup programs only need access once.
- Personal Internet Firewalls that really work! explains some of the issues.
- ZDNet notes that personal firewalls could leak private info.
"Easy" Solutions Have Drawbacks
Firewalls with ready-made lists of "acceptable" programs probably aren't the safest way to configure a firewall for security — at least not unless you are able to easily change those settings.
Popular Programs Often Poorest Choices
While firewalls preset to allow the most common programs are an attractive feature, the most popular products are often not the safest to use.
If you've spent any time on this site, it will be clear to you that commonly used Microsoft products are some of the worst choices when it comes to security.
Can You Determine Program Access?
You should have the ability to determine for yourself if a program needs access. Disabling access for lesser-known (but more secure) products does no service to the user and may have more to do with the lack of research by the vendor than actual safety issues.