Cisco’s Internetworking Operating System, or IOS, is a family of network operating systems that is used on several models of the company’s routers and switches. IOS enables routing, switching, internetworking, and a variety of telecommunications functions on a whole series of Cisco network device platforms. IOS has gone through several phases of evolution, and any […]
How to Configure SNMP on Cisco Devices (Routers, Switches)
Simple Network Management Protocol (SNMP), so “simple” yet so powerful. SNMP delivers a standardized framework that can be used for the monitoring and management of network devices. SNMP is one of the most powerful tools that can be used by today’s network administrators and engineers. SNMP allows admins to poll for data such as CPU […]
Comparing Cisco IOS Configurations (Config Compare Tools)
In our day to day work as network administrators it is often necessary to compare configuration files of Cisco routers, switches, firewalls etc. As we know, a characteristic of Cisco IOS is that the configuration files are stored in text format, but still a line by line comparison of different config files is tedious and […]
Cisco Access List Configuration Examples (Standard, Extended ACL) on Routers Etc
An Access Control List (ACL) is a list of rules that control and filter traffic based on source and destination IP addresses or Port numbers. This happens by either allowing packets or blocking packets from an interface on a router, switch, firewall etc. Individual entries or statements in an access lists are called access control […]
PPTP Remote Access VPN Configuration on Cisco Routers
One of the easiest ways to configure simple remote access VPN functionality for your remote users is by configuring PPTP. This is supported on Cisco routers and will work with Windows OS flawlessly. What is PPTP PPTP (Point to Point Tunneling Protocol) is a quick and easy solution to offer remote access to users. Since […]
Cisco IOS Zone Based Firewall Configuration Example (ZBF)
In this article we will consider the topic of Cisco IOS Zone Based Firewall (ZBFW). Cisco IOS Zone Based Firewall allows us to define Security Zones and to give each zone its own policy. What is Zone Based Firewall At the very beginning of Cisco routers, the implementation of firewall functionality on IOS router devices […]
How to Disable Telnet and Enable SSH on Cisco Devices
I should have written this article from the very beginning of starting this blog because it is one of the most fundamental configuration steps for managing a Cisco networking device (router, switch, firewall etc). Disabling Telnet and enabling SSH on a networking device is also a step forward in increasing security in the whole network. […]
Six DoS Vulnerabilities in Cisco IOS Software – Patch your devices ASAP
On March 26, 2014 Cisco has announced six serious security vulnerabilities (five vulnerabilities in Cisco IOS software and one in Cisco 7600 Series Route Switch Processor 720 with 10 Gigabit Ethernet Uplinks). If the vulnerabilities are exploited they can result in Denial of Service condition for the devices. All six vulnerabilities have a CVSS base […]
How to Configure IP Traffic Export on Cisco Routers
Have you ever been in a situation where you needed to capture traffic going through a router? Have you ever wished you had a switch available to create a SPAN port? Have you ever asked why you took that small hub out of your computer bag? With all of these tools you could have simply […]
Cisco IOS DHCP Configuration
One of the most exciting pieces of configuration within Cisco IOS, in my opinion, is IP DHCP Pools. With this feature we can configure a Cisco switch or router to act as a DHCP server. This ability is useful in several cases including some of the following; small business DHCP sever, disaster recovery DHCP server […]