Port Blocking

It seems like everyone has a router these days, but not everyone understands how to take advantage of their features. I'm going to show you some common protocols to block and how do it my Linksys router. This feature can not only be used to block unwanted traffic, but can also be used to protect your children from adult content. Home routers do not offer the same protections as their enterprise counterparts, but a little traffic filtering can go a long way. Here are some basics:

The picture below shows the Access Restrictions and protocols blocked on my first rule. On this router, only 3 protocols can be blocked per rule. As you can see, the policy is enabled and I have it applied to every PC on my network (not shown). I'm not blocking access to any PCs nor do I have any website filters setup. To filter websites, simply fill in some keywords or actual web addresses in the appropriate areas and save your changes. This feature can be used in conjunction with, or if you are on a tight budget, instead of nanny softwares. It offers some protection for your kids, or any annoying websites you wish to block. Again, you can setup multiple rules to block additional sites.

As you can see, I have blocked Telnet (shell access), SNMP (simple network management protocol), and TFTP (trivial file transfer protocol) on this rule. Some additional protocols to block are SMB (Windows file sharing), VNC (remote control software), and RPC (windows remote control protocol). For more effective filtering, research the protocols in use on your network, and block the ones that are not in use. A complete list of ports and their assigned protocols can be found at www.iana.org/assignments/port-numbers

Port blocking and web filtering aren't difficult to achieve with home routers and offer another layer of protection against the outside network. Filtering is not only good for children, but it can be used to protect the integrity of your network by blocking out spammy or other suspicious sites.