Archive for October, 2008

Content Based Access Control “CBAC”

Tuesday, October 21st, 2008

In the beginning God created heaven and earth, and then he created routers, so packets could flow from one part of the earth to the other. As he rested he looked down on his creation and smiled for all was good. Packets were flowing from one interface to another. Then as he beheld his creation he watches as some pad packets decided to flow where they didn’t belong! So God created access-lists and again everything was as it should be, packets only flowed to areas where they belonged. After some time naughty packets found out that they could sneak by God’s great protectors of the network by setting the ACK bit in their headers.

(more…)

Introduction to access-lists part 2

Thursday, October 16th, 2008

In the second installment of our guide to access-lists we are going to talk a little about named access-lists, how they work, what the benefits are, and how using them allows us to create reflexive access-lists. Named access-lists are exactly what they sound like, they are an extended access-list that has a name instead of a number. One of the nice features of named access-lists is that each line of the access-list has a number. this way you can delete just one line in an access-list without removing the whole access-list. You can create a named access list by using the following command.

(more…)

Introduction to access-lists part 1

Wednesday, October 15th, 2008

Today I would like to take some time and talk about security. I want to discuss access-lists, extended access-lists, reflexive access-lists, and CBAC or content based access control. Learning how to properly use access-lists is so crucial to becoming a good network administrator. They are vital to securing your network and as you progress with your studies you will find that access-lists are used quite extensively in routing, QoS, and other important things.

(more…)

Replace a running config without reloading!

Saturday, October 4th, 2008

The new Cisco IOS 12.4 train has many new features that any engineer will find useful; one of the features that fix a pain point for me is the new config options available in 12.4. Have you ever been in a situation where an entered configuration does not work as expected? Now usually you have to back out the configuration one command at a time and hope for the best. Sometimes you may even reach a point where you can not completely remove a configuration without reloading the device, this is the case sometimes when trying to remove sub interfaces. Now if this is a datacenter or work environment then you may not be able to reload the router.
  (more…)

Categories
Support Our site