I’ve been working on doing some multicast labs lately and am constantly resetting my lab devices to their default configs and starting from scratch. As many of us know, to enable PIM on all of your interfaces you must go into each interface and enable it manually. There is no default command to enable PIM on all interfaces. We know PIM should be enabled 1 to 1 with interfaces involved in routing making this a boon. With that in mind, and the fact that I am rather comfortable with the concept of needing PIM on the interfaces, and likely speak and type this command in my sleep, I decided to make it easier and modify a previous TCL script I had written to enable PIM on every interface that has an IP address assigned to it. With the great “Send to Chat” feature of SecureCRT I can do this across my entire topology on one fell swoop. In a real world environment, you could use a tool like Solarwinds to push this out to your devices.
Category: Real World
Bulk enable PIM via TCL
Permanent link to this article: https://www.packetpilot.com/bulk-enable-pim-via-tcl/
Daily Learning Actions
The other night while studying I tweeted out the first six words that came to mind as I thought to myself “How can I retain this better”. The concept is really quite simple and I find myself doing these steps for everything I am trying to learn and retain. While everyone learns *best* a certain way, everyone also learns more by being around the material more. I don’t feel I need to explain how to find what way of learning works best for you. Nor am I going to pretend to have a clue how people learn or retain better in any sort of scientific way. I’m simply going to explain my view on my six word study method.
The Method:
Read, watch, listen, learn, discuss, do!
It’s a simple mantra that you can think about every time you start studying a topic. In fact, you already learn all of these ways throughout the day. The concept here is to apply all six of them to every topic you are focused on studying.
Permanent link to this article: https://www.packetpilot.com/daily-learning-actions/
Apps for a Network Engineer Part II: Windows
Windows for Network Engineers
Part two in my series of apps for network engineers across the three major platforms. I previously did the post for Mac when I first refreshed my laptop and purchased my first new Mac in 8 years. Issued by work, my daily laptop is a Windows machine which is fine with me. I would prefer to use Mac but give me a machine that has the tools I need and I’m fine. So with that in mind, I am going to list my favorite Windows tools for Network Engineers.
Permanent link to this article: https://www.packetpilot.com/apps-for-a-network-engineer-part-ii-windows/
Linux to Cisco Openswan IPSec Configuration
[notice]For this example I use the following IP scheme 192.168.0.12|–O–42.42.42.42—–[INTERNET]——12.12.12.12–O–|10.42.42.42[/notice]
I was approached a few weeks back to assist in creating a VPN Tunnel between two end points. Of course in my naivety I readily assumed it was between to Cisco devices but that turned out not to be the case. The tunnel was to be between a Linux box (in this case Ubuntu on a hosted VPS provider) and an unknown endpoint. This tunnel was going to be host to host as opposed to LAN to LAN. After some quick discovery work, getting access to the Linux box, and seeing the required proposal from the other side I started diving into the unknown of Openswan. Luckily, after doing som research for the configuration and verification things started shaping up and much to my approval, a lot of what you would look for in Cisco verification was the same on the Linux box. The configuration goes as such.
Naturally the first step is to install Openswan. As per usual use your distributions software management to install this. The first thing I configured was the ipsec configuration file. On the Ubuntu box this resided in “/etc/ipsec.conf”. The configuration was as follows.
Permanent link to this article: https://www.packetpilot.com/linux-to-cisco-openswan-ipsec-configuration/
Trouble shoot with TDR
This article is another example of trouble shooting by putting multiple pieces together. While it relies upon existing knowledge of the environment in which the article is based it should prove to be a good example of a trouble shooting process that will hopefully be able to spark some creative thinking the next time you have a problem that needs to be resolved.
The scenario starts out with a user ticket stating that the phone isn’t working. After some fact gathering the below details and possible solutions were outlined.
Continue reading
Permanent link to this article: https://www.packetpilot.com/trouble-shoot-with-tdr/
It’s not defeat unless you quit.
Too often when talking to individuals studying for certifications tests, or just entering their field, I find them to quick to throw their hands up and say “I don’t know, it’s to far beyond me” and that is where their interest stops. They keyword I am saying their is stops. While yes, I am going to correlate much of this post to my career in information technology, this concept proofs true in all aspects of life.
So what am I getting at? Basically, I’m saying you don’t have to admit defeat. One of the best things in this industry, and your day to day life in general, is to learn what you don’t know. Contrary to my above statement, saying “I don’t know” isn’t giving up. The first thing is to admit when you don’t know, but don’t stop there, because pretending you do is a good way to get caught with your pants around your ankles. You have options as to what you do after you realize that you don’t know. The first is to follow up with “but I can find out”.
You could be saying that you’ll find out to an individual that asked you the question, or you could be saying it to yourself. The trick here is to follow through. Do some research on the internet, look up a video, find an example of the desired end result. Doing this means you haven’t thrown your hands in the air and given up, and therefor, you haven’t been defeated.
Next, you can take the opportunity to show your desire to move forward. Lets say you are asked to do a task you don’t know how to do. Follow the above concept, but say “I’m not sure how, can you show me”. This again doesn’t correlate to defeat. It is an acknowledgement of not knowing something, but having the determination to learn about it and progress.
The long and short of it is this, not knowing how to do something, having it be outside of your current skill set, or having it currently reside above your understanding is NOT a representation of your capability to do or perform the request. Only if you give up on proving you are capable have you admitted defeat.
Permanent link to this article: https://www.packetpilot.com/its-not-defeat-unless-you-quit/
Apps for a Network Engineer Part 1: MAC
MAC for Network Engineers
I am not going to play bias in anyway towards any particular apps. I’m surely not going to get into the debate between Windows or Apple as a primary computer. In fact, I’ve spent the last 4 years using Windows exclusively for work due to work issued laptops and the lack of support for Mac in the companies I have worked with. However, I recently purchased a new Mac to get back to what I personally like best, with that, I had to rebuild my app repetoir for doing my job on a Macbook. This took some digging and searching to find apps similar to what I used on Windows. I’m still searching for all the app alternatives but I figured I could make this into a working document of my favorite apps in terms of network engineering.
Permanent link to this article: https://www.packetpilot.com/apps-for-a-network-engineer-part-1-mac/
SRT: Offline type 7 decrypt
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.
R1(config)#key chain tempkeys R1(config-keychain)#key 1 R1(config-keychain-key)#key-string 7 06150A225E4B1D12000E R1(config-keychain-key)#exit R1(config-keychain)#key 2 R1(config-keychain-key)#key-st R1(config-keychain-key)#key-string 7 095F4B0A0B0003190E15 R1(config-keychain-key)#end R1# R1#show key chain Key-chain tempkeys: key 1 -- text "secretkey" accept lifetime (always valid) - (always valid) [valid now] send lifetime (always valid) - (always valid) [valid now] key 2 -- text "secretkey" accept lifetime (always valid) - (always valid) [valid now] send lifetime (always valid) - (always valid) [valid now]
Permanent link to this article: https://www.packetpilot.com/srt-offline-type-7-decrypt/
Tracked Static Default Route
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.
Permanent link to this article: https://www.packetpilot.com/tracked-static-default-route/
Overlapped IP Range in a Merger
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.
Permanent link to this article: https://www.packetpilot.com/overlapped-ip-range-in-a-merger/