Recent posts

GNS3 IOS Memory Errors

September 23, 2011

Update: Please see this page for a fix to this issue. The other day I decided to upgrade my GNS3 IOS to c3725-adventerprisek9-mz.124-15.T14.bin. All seemed to be going well until I tried to issued the “ip nat inside” command on one of the interfaces… R1(config)#int fa0/0 R1(config-if)#ip nat inside % NBAR ERROR: parsing stopped % NBAR Error : ...

Connecting Your PC to Your Virtual GNS3 Routers

September 18, 2011

Update: Please also see my Virtual Equipment + Physical Equipment = Big Lab post for more information. As you already know, GNS3 allows you to create virtual routers on your PC. What some people struggle with is connecting their physical PC to their virtual GNS3 network. In this blog entry, I’ll explain how this can be done using GNS3’s cloud o...

URL Redirects using NAT

August 30, 2011

In my previous post, Router URL Filtering using NBAR, I explained how it was possible to block users from accessing websites simply by using NBAR, a class-map and a policy-map. In this post I’ll describe how you can redirect your users’ web requests instead of simply blocking them. This time we’ll use NAT instead of NBAR. For this example, let...

Subnetting Made Easy - Formula

August 29, 2011

I covered subnetting in my earlier posts, Subnetting Made Easy, Part 1 and Subnetting Made Easy, Part 2. In the latter mentioned post, I explained how you can use simple additions or subtractions to work out the First Usable Address, the Last Usable Address and the Broadcast Address of a subnet. As the post was quite long, I thought I should r...

Router URL Filtering using NBAR

August 29, 2011

There are many ways you can block users from accessing websites they shouldn’t be, such as firewalls, proxy servers, DNS servers, etc. However, if you have a small setup, chances are you may not have any of these in place already, and you may be reluctant add another piece of equipment to your network. This is where your Cisco router can come t...