Initial Router Setup For Remote Access

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The following lab can be completed using any Cisco Emulator supporting the appropriate feature(s).

The purpose of this lab is to reinforce basic router configuration including naming the router, connecting two routers via an ethernet connection, and establishing logon procedures for remote access including secure remote access. Remote access if a key design feature of any network. It provides efficiency of management by preventing unnecessary trips to distant devices for simple tasks. Secure access is provided to prevent unauthorized access and data gathering from packet captures on plain text traffic.

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SRT: Offline type 7 decrypt

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I was recently working on deploying a new device into our network infrastructure. I was working off a configuration template that had a standard arguments for AAA leveraging TACACS+. I was offsite and had asked a fellow colleague to enter the new device into our ACS deployment to allow authentication and command authorization. The long and short of it is, it was copied off of a different group of devices than what my configuration template was based of. The issue was a mismatch in TACACS server keys. The problem was I was currently offline as I was connecting to the device what would let me out to the network. So what is the stupid router trick? The stupid router trick consists of using the key chains to decrypt a type 7 TACACS (or other key) that is hidden via service password-encryption in your configuration template. The trick is pretty simple. Create a temporary key chain that won’t be applied anywhere, enter the key(s) into the key chain in their type 7 format, and then do a simple show key chains. Really! That’s all there is to it. See the output below.

 

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Automated IP Communicator Launch against Multiple Clusters

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If you manage multiple CUCM clusters you are likely to have Cisco’s IP Communicator installed on your computer. Cisco IP Communicator is a software based phone installed on your computer that connects up to CUCM and lets you utilize your PC as if it’s a Cisco desk phone. This is a pivotal tool to quickly move a phone between different call managers. I recently fell into this demographic while working on a migration/collapse of multiple CUCM clusters. A lot of time was spent in the GUI of IP Communicator changing TFTP Server address (let alone trying to remember them all). I took a couple of hours and figured out what would be needed to automate this task via a batch script with a simple menu based script. The details are found below.

To start, I found that the TFTP servers were stored in the registry. However, these TFTP servers were not in standard IP address form. They were actually stored in Hex, but the octets were rolled over while keeping the bits in the standard left to right order. The process to create the correct value’s for the registry is as follows.

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Tracked Static Default Route

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As common place in today’s networks redundancy is key. Applications are the key components to business obtaining revenue. More and more applications are becoming SaaS and ecommerce is here to stay. With that being said, many companies are moving to redundant connections to the internet. These connections could be through two different ISPs, or both connections to the same ISP. Often times these connections will be of different speeds to save on costs. The key to these connections is to maintain internet connectivity.

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Cisco OSPF MD5 Authentication

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Continuing with our OSPF and interior gateway protocols we will not look at an MD5 implementation utilizing OSPF on a Cisco router. We will again continue with our 3 router topology as used in both the EIGRP MD5 example and the OSPF plain text example. There are very few changes that will need to be made to our earlier OSPF example using plain text. The topology is as follows.

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Cisco OSPF Plain Text Authentication

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Continuing with our interior routing protocol discussion on authentication we are going to look at Cisco OSPF implementation of plain text authentication. While this isn’t the most widely used model for authentation with OSPF it is a viable option. The topology we are going to use is the same topology from the EIGRP authentication example. The steps may feel familiar as well.

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Overlapped IP Range in a Merger

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The Scenario is this…Company A has purchased Company B. One is an enterprise of thousands of users, the other a mid size company in the multiple hundres. However, as would happen to be the case, both companies utilize an overlapping subnet. To further complicate the issue it has been decided that both companies need to terminate at Company A’s core and utilize a single unified instance of EIGRP. As part of this scenario, both companies need to be abble to access each others networks but luckily it has been determined that neither need to be able to access each others overlapped networks. Additionally both companies advertise different bit masks on their overlapping networks. This is something that we can work with.

The following examples show the additional configuration required for the specific scenario above. The full router configurations are posted at the end of the article.

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Router on a Stick

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The scenario looks like this. You’ve got a branch office with a single router connecting to your corporate office over the WAN. In your branch office you have a single layer 2 switch and a desire to separate traffic into multiple broadcast domains. Maybe you want an easy way to allow only HR computers to connect to a very specific branch office server and the only place for any restriction of traffic is on that branch office router. Here is where your router on a stick comes into play.

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Cisco DHCP Configuration

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DHCPTOPOLOGY

Cisco routers are capable of doing many more things than simply routing packets. In fact, it can operate as a small DHCP server when needed. By no means is it a replacement for your enterprise, centrally managed DHCP server but it does have its applicable scenarios. Lets say you have a branch office that has its own server for any particular reason. Maybe it is a local file share for an engineering departments CAD program and rather than having all file traffic from opens and saves traverse the WAN during the day, you simply run backs of that server across the WAN at night. Continue reading

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Static Routing with Cisco

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Routing is at the core of the network infrastructure. Routing is what ultimately lets you get from point A to point B not only in your own network, but also across the entirety of the world wide web. Routing in its simplest form tells your network devices the path to get to another network device located on another network. This was originally handled by creating static routes to the required destinations.

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