The big difference between the enable password and the enable secret is the encryption level. The enable password by default is saved in clear text so when looking at the running-configuration of the router you will be able to read the password. It is possible to encrypt this password using the service password-encryption command. The […]
Before looking at how to mitigate a Smurf attack, let’s first understand what it is and why it’s such a problem. A Smurf works on a weakness of IP and ICMP by sending an ICMP packet to the broadcast address of a network. For example, I could send an ICMP (Ping packet) to every computer […]
IP spoofing is the act of camouflaging your IP address to make it look like you are someone else. Although IP spoofing is not an attack by itself, it is the starting point of many of the most common attacks found on today’s networks. Most, but not all, of the spoofing attacks that take place […]
One of the first and most important things to configure on any Cisco device after allowing telnet or SSH, is to restrict who is allowed to access the device. Of course having a password on the lines is the first step and often configured correctly. The unfortunate thing about password security, especially when discussing telnet, […]
Access-lists are the cornerstone of security in networking. They are used on Routers, Switches and Firewalls and are often a challenge to understand when first starting your career in networking. Before we dive into the configuration of access-lists, or otherwise known as ACL’s (Access Control Lists), it’s important to get an understanding of the concepts, […]
In order for 2 VLANS to be able to communicate, the traffic must be routed. This can be done either by a multi-layer switch which will have routing capabilities, or the packets can be routed by a router (Router on a Stick) As an example, I have 2 VLANS, VLAN 10 and VLAN 20 which […]
VTP (VLAN Trunking protocol) is a protocol used to replicate the VLAN information across switches, however there are a few things that must be made clear… VLAN information will only be sent on trunk ports Only the VLAN identity is replicated, NOT which ports are configured to use that VLAN! Maintains database consistency through a […]
Although the configuration of speed and duplex is incredible easy, the concept behind them is somewhat important. Duplex defines how traffic will be sent and can be related to a 2-way radio vs. A telephone. With a 2-way radio, more so when there are more than 2 people on the same radio frequency, only 1 […]
A VLAN is a Virtual LAN which allows us to logically separate computers on our network. In previous years, an office would have a physical switch or hub in each office, and offices were structured around the job function. In other words, all sales people would be in the same office and would all be […]
In order to control what machines are plugged into your network, Cisco introduced the “switchport port-security” command. In this tutorial I’m going to explain how to use this command, and different options available using it. Below is the breakdown of the commands I used in the live demo, and an explanation of each. AOIP.ORG_Switch# terminal […]
Once VLANS have been defined on a switch and you have placed ports into their corresponding VLANS, traffic is limited to remain inside it’s Virtual LAN. The only way for traffic to leave the switch, is to have it sent on a port that is in the same VLAN as its source, or sent over […]
Almost 100% of Cisco switches will have a 50 second delay on a port before it goes live. What this means, is that when you plug a new device into a switch such as a PC, there will be a 50 second delay before the port will become active and the PC will be able […]
