97 posts tagged Cisco IOS

What is GNS3 ? GNS3 is a graphical network simulator that allows you to design complex network topologies and to launch simulations on them. To allow complete simulations, GNS3 is strongly linked with : Dynamips, an IOS emulator which allows users to run IOS binary images from Cisco Systems.

DHCP snooping is a DHCP security feature that provides security by filtering untrusted DHCP messages and by building and maintaining a DHCP snooping binding table. An untrusted DHCP message is a message that is received from outside the network or firewall causing denial of service attacks.

I’ve never bothered to memorize the Cisco descriptions of IP Precedence values (i.e. IP Precedence 4 is “flash-override”).  I’ve hit a couple of labs which ask you to manipulate traffic based on these descriptions.  For instance: “Drop all flash traffic coming into r1 from VLAN 6.” Some commands

Topic: OSPF You are rolling out 10 Gigabit links across your core network.  You are running OSPF in your core.  You’ve noticed that the OSPF cost for the new 10 Gigabit links is 1.  This is the same as your FastEthernet and Gigabit links.  You are tasked with configuring the core routers so that the 10 Gigabit links will have a default OSPF cost of 10.

A security researcher has developed malicious rootkit software for Cisco’s routers, a development that has placed increasing scrutiny on the routers that carry the majority of the Internet’s traffic. Sebastian Muniz, a researcher with Core Security Technologies, developed the software, which he will unveil on May 22 at the EuSecWest conference in London.

Topic: OSPF r1 and r2 are running OSPF in area 0.  They have established a neighbor adjacency over a single serial interface.  Configure LSAs on both ends of this adjacency to set the DoNotAge bit.  Do not use the ‘ip ospf flood-control’ command.

What's in This Book The first four chapters cover what would be considered essential system administration functions if a router were a server. Chapter 1 covers router configuration and file management issues. In Chapter 2, we turn to useful router management tricks.

It’s time again for another Cisco EoL / EoS announcement batch. We’re all the way up to #38 now! This batch has a little bit of everything, so stay sharp. Don’t forget, most EoL / EoS announcements include a list of product migration options. If you need help deciding what product is best for you, send me a message with the Slaptijack contact form.

Topic: OSPF r1 and r2 are running OSPF in area 0.  They have established a neighbor adjacency over a single serial interface.  Configure LSAs on this adjacency to set the DoNotAge bit. Yesterday’s Question Question Of The Day: 12 May, 2008  Topic: RIP r1 is a high-end router running RIP on

If you want to allow a low-priviledged user on a Cisco router or a Switch to view the Startup Config then this can be done in Routers and Switches running Cisco IOS. This infact is a simple 2 step procedure as follows: (more…)