Setting up the IPv6 and IPv4 SPI Firewall Protection of the Linksys Wi-Fi Router

The SPI Firewall Protection feature keeps track of the state of network connections traveling across it.  This feature protects your internet connection against threats and Denial of Service (DoS), which is why it is recommended to keep it enabled.

A DoS attack is an attempt to make an internet connection unavailable to the intended users by overloading the network to a point where it can no longer respond to legitimate traffic.

This article will discuss how to configure your router’s IPv6 and IPv4 SPI Firewall Protection for your connections.  To do this, follow the steps below:

NOTE:  Not all Linksys Wi-Fi Routers are IPv6 compliant.  Click here to know the devices that support IPv6.  The image of the web-based setup page may differ depending on your router model.

Step 1:
Open a web browser and access your router’s web-based setup page.

Step 2:
Click the Security tab and select the Firewall sub-tab.


 User-added image

Step 3:
Click the radio button beside the SPI Firewall Protection option/s you want to enable.



NOTE:  Enabling SPI Firewall Protection will block the Denial of Service (DoS) attacks.  A DoS attack does not attempt to steal data or damage your computers, but it overloads your internet connection so you cannot use it.

If you are using older Linksys routers, the web-based setup page may look similar to the image below:

User-added image

Step 4:
Select the Internet Filter options you want to enable.


  • Filter Anonymous Internet Requests – This feature keeps your network from being detected by other internet users.  It also hides your network ports, making it difficult for outside users to access your network.  This option is set to enabled by default. 
  • Filter Multicast – This feature blocks multicasting or the method of sending IP diagrams to a group of receivers in a single transmission.  This option is set to disabled by default.  Select this option to enable filter multicasting.

NOTE:  IP multicasting is widely used in enterprises, commercial stock exchanges and multimedia content delivery networks such as IPTV applications.  If you do not use such applications, it is advisable to keep this option disabled to protect your network from spoofing or Denial of Service (DoS) attacks.

  • Filter Internet NAT Redirection for IPv4 Internet Only – This filter prevents a computer within the network from using a URL or a public IPv4 address to access the local server.  This option is disabled by default.
  • Filter IDENT (Port 113) – This filter keeps port 113 from being scanned by devices from the internet.  This will protect your network from unauthorized access to services such as POP, IMAP, SMTP, IRC and FTP.  The Filter IDENT option is set to enabled by default.

Step 5:
Select which applications to filter out in the Web Filter option.

NOTE:  This option is currently not available on the Linksys E4200.


•  Proxy – This filter blocks internet proxy servers.
•  Java – This filter blocks Java content on websites.
•  ActiveX – This filter blocks ActiveX content on websites.
•  Cookies – This filter blocks cookies or data stored on your computer and used by websites when you interact with them.


NOTE:  These options are unselected by default.

Step 6:
Once done, click .

Related Article:

Differences between IPv4 and IPv6

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