In order for two Layer 3 devices (routers or layer 3 switches) to be able to exchange routing information, it is necessary to use the same routing protocol, such as RIP, EIGRP, OSPF, BGP, etc. Different routing protocols, or protocols configured differently (eg different EIGRP autonomous system) do not exchange information. However, when a device […]
DoS Protection on Cisco 7600 Routers and IP Networks
The Cisco 7600 router is in my opinion one of the most versatile High End routing machines on the planet!! It is one of my favorite networking devices. If you take a look at Cisco website under the Routers Product Category, you will notice that the 7600 can be used in Data Centers, in Service […]
Cisco Router Password Recovery-How to recover cisco router lost password
One of the most frustrating moments as a network administrator is when you desperately want to log on to a Cisco router and you try all possible passwords you have with no success. Fortunately there is a Cisco password recovery procedure for IOS routers which you can follow and bypass password control in order to […]
BlackHat 2009 Router Exploitation Presentation
I was reading an interesting presentation the other day, taken from BlackHat USA 2009 Briefings from Felix Lindner, and thought about sharing the main points here. The guy presents a reasonable analysis of the current situation regarding Router security and exploitation. As we all know, routers are exploitable of course, but not as easy as […]
How to Configure DHCP on Cisco 851 or 871 Router
DHCP stands for Dynamic Host Configuration Protocol. Basically it’s a mechanism which assigns IP addresses to computers dynamically. Usually DHCP is a service running on a server machine in the network in order to assign dynamic IP addresses to hosts. All Cisco 800 series models have the ability to work as DHCP servers, thus assigning […]
Cisco Router 851 – 871 Interfaces and Basic Configuration Guide Setup
Cisco manufactures routers for all markets, ranging from SOHO up to large service provider models. The Cisco Router 800 series belongs to the lowest SOHO end. The most popular models in the 800 series are the 850 and 870 broadband access models which come with different types of WAN broadband interfaces (the difference between 850 […]
Configuring NAT on Cisco IOS Routers
The depletion of the public IPv4 address space has forced the internet community to think about alternative ways of addressing networked hosts. Network Address Translation (NAT) therefore was introduced to overcome these addressing problems that occurred with the rapid expansion of the Internet. Even if NAT was suggested as a temporary solution, it has been […]
Blocking peer-to-peer using Cisco IOS NBAR – Configuration Example
Cisco IOS Routers support application traffic classification using the Network Based Application Recognition (NBAR) feature. This brings application intelligence to the Layer 3 router device, putting more value into your network infrastructure. NBAR is usually used for classifying mission critical applications in order to apply Quality of Service and bandwidth guarantees in the network. Another […]
Administrative Distance of Routing Protocols
Cisco Routers support many dynamic routing protocols for learning routes in a complex network topology. The routing protocols supported are the following: RIP OSPF BGP IS-IS IGRP EIGRP Each routing protocol has its own Administrative Distance (AD), which is a value representing the trustworthiness of the specific routing protocol. If a router learns a destination […]
IOS Packet Capture and Auto Upgrade
IOS Packet Capture Finally there is a feature that was missing from IOS in the past. This is the ability to easily capture packets travelling through the router, and export the captured data to PCAP format so that you can view it with third party tools (like Wireshark). This feature is useful also when doing […]
Cisco 800 Series Router Models
The Cisco Integrated Services Router (ISR) technology concept, that was initially implemented on 1800, 2800, 3800 series, is now available on the small office and small business models in the 800 series routers. The ISR technology integrates several networking and security features on one device, such as wireless networking, security firewall, virtual private networks, quality […]
Configuring PPPoE for Cisco Router 520 and for series 850 and 870
The Cisco 520 Ethernet to Ethernet router can be used as a PPPoE Client (Point to Point over Ethernet) to connect a small office to a DSL service for Internet access. Also, using Network Address Translation (NAT), you can connect multiple computers to the Internet using the same router. The same configuration applies also for […]
Cisco new Router Series ASR 1000
Cisco announced recently a new WAN Router model, the ASR 1000 series. This is a high performance integrated services device, which can be used for both Enterprise and Service Provider networks. One of the key hardware design features of this router model is its Cisco QuantumFlow processor which can support any current and future services […]