Router on a stick

Today I will show you how to build a so called “Router-on-a-stick” environment. In this example we have one Cisco router, one HP ProCurve switch and three subnets: First we configure inspection firewall profiles, so when someone requests packets from the internet, packets can come back through our inbound WAN interface access-list ip inspect name … Read more

Copy IOS image to a Cisco router from ROMmon

If you accidentally erased your flash or have a Cisco router with an empty flash, you can upload an IOS image from ROMmon to recover the device to a functional router. Connect your router via console-cable to a PC and use PuTTY to connect to your device. I use TFTPD32 from Philippe Jounin. When starting … Read more

Password- and configuration-recovery for Cisco IOS router

You bought a used Cisco router at eBay configured with a password? You loose your password but still need the current configuration? No Problem! You can easily reset the configuration/passwords. You need to connect to the serial port of the Cisco router. I’m using always a USB-RS232-serial-adapter and PuTTY for this. To boot your router … Read more

Site2Site IPSec VPN Tunnel with Cisco EasyVPN

In Germany some internetprovider doesn’t offer a static WAN IP address. So the easiest way to connect a branch office router via IPsec VPN protocol to the central network address is using a Cisco EasyVPN connection with network-extension mode. In this example we have two networks: The IP subnet of our mainoffice is 192.168.1.0 /24 … Read more

Understanding ip nat outside Rules

One of my customers has a separated network within their internal network. Mobile devices (Android Phones, iPhones, etc.) are connected to a consumer access point which is connected behind the Cisco Router 876:       The Traveler service is also rechable via internet (configured with PAT pointed to the Traveler server). In the past, … Read more