Network filtering is a technique that you can configure your firewall to control the flow of incoming and outgoing packets based on the source and destination Ip address.
Generally, we define rules in a firewall device to allow and deny a certain traffic based on source IP address and destination IP address. Let’s say you want to block facebook.com in your home network. How do you do it? You create a rule in a gateway router(router has an embedded firewall) of your home or office, such that
Block -> domainName -> facebook.com.
What if your home router or an office router doesn’t have a packet filtering capability, then you are out of luck, You cannot filter the traffic. Oh! just kidding you can.
There is a service called OpenDNS which provide the network filter service based on the DNS request.
According to them,
OpenDNS is a company and service which extends the Domain Name System by adding features such as phishing protection and optional content filtering
To use OpenDNS service, first, you need to create an account on OpenDNS. OpenDNS has a free plan for home internet security. Follow this link to signup for free home security from OpenDNS.
Free service supports only one public IP address. If you want to support more than one public IP, then you need to switch to other plan or create multiple OpenDNS account.
If your Public IP address changes frequently, then you can use ddclient or Dynamic DNS updater to update the changed IP address. Take a look on this post how to deal with dynamic IP address in OpenDNS.
To Configure OpenDNS, signup to the OpenDNS website and choose OpenDNS home service plan as shown below.
Enter the required fields and signup as shown below.
After signing up, verify your email address and your Public IP address. Now it’s time to add your public IP address to OpenDNS services and filter the traffic as shown below.
Go to your account and add a Network as shown below.
open DNS will automatically detect your public IP address
Give a name to your filtering rules and click done as shown below.
Apply the filtering rules as shown below and click on apply.
Now, the setting up content filtering has been almost finished, if you would like to filter more categories, you can check other categories as well. It’s time to configure your router or a firewall to use this Filtering policy.
The configuration on router varies from manufacturer to manufacturer. I have a Digicom DSL router and I will show you how to configure this DigiCom DSL router to use OpenDNS content filtering policy.
To configure the router, log in to a router and go to Local Network setup and change the DNS server address as shown below.
DNS Server 1: 220.127.116.11
DNS Server 2: 18.104.22.168
You can visit the link to see how to configure the specific routers and operating system(Windows, Linux, Mac) to use OpenDNS service.
So, now it’s time to test the configuration. Open your browser and try to visit any social networking site. On visiting social networking sites, you saw that your connection is not private. Voila!, that’s it.
I hope this post helped to set up content filtering policy in your office or in your home network using OpenDNS service.