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What keeps unauthorized users from accessing my IP address/Internet?

Our network security expert explains how to keep unauthorized users from accessing your router's IP address for Internet access in this advice explaining how proxy servers can solve client control issues.

I have a Pentium 4 desktop PC on which an email server program is running. We are connected to the Internet via a router. We have a Class C network.

Many times we have found users who are not authorized for Internet, use the router IP address as a gateway and access to the Internet. Normally, our practice is to change the node address of the router (for example, if originally it was, we change it to

Now I want to change the IP addressing of the router and make it However, when I do this, none of the authorized users can access the Internet since the class of the network of the router changes. How do I implement this change and have the authorized users access the internet?

Proxy is the solution to your problem. A proxy server sits between your clients and Internet allowing only authorized traffic to pass through it. Proxy lets you configure the clients that need the access to Internet, based on different parameters like IP-based or user-based and allows you to define the time range during which the Internet can be accessed by these authorized clients. There are many open source proxy solutions available that you can download and install for free.
This was last published in January 2009

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