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Cisco IPsec VPN breakage on Windows 8[.1] and OS X 10.9

Oh, to be a Cisco IPsec VPN user these days… Now I know that we should get with the program and move to AnyConnect, since Cisco is EOL-ing the venerable Cisco VPN Client in 2014, but we have a large installed base, and since Cisco stopped making IPsec clients for Mac and Linux back in the […]

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The post Cisco IPsec VPN breakage on Windows 8[.1] and OS X 10.9 appeared first on Packet Pushers Podcast and was written by Will Dennis.

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Securing a DMVPN spoke – Part 2

In Part 1 we went through protecting the spoke from the outside world on the Internet and using the stateful inspection firewall CBAC, Content-Based Access Control, to dynamically allow returning traffic back in. CBAC works great for a single inside zone and a single outside zone. What if your business requirements have more than two […]

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The post Securing a DMVPN spoke – Part 2 appeared first on Packet Pushers Podcast and was written by Charles Galler.

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Dotless

It was never obvious at the outset of this grand Internet experiment that the one aspect of the network’s infrastructure that would truly prove to be the most fascinating, intriguing, painful, lucrative and just plain confusing, would be the Internet’s Domain Name System. After all, it all seemed so simple to start with.

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GNS3 topology for INE Workbook

How does the internet work - We know what is networking

Now that my topology in GNS3 is exactly as in INE Workbook 1 I can share it with you if you don’t want to do all the basic configurations and connections by yourself. After spending too much money on different rack rentals in the past few months I decided that I will definitely need to […]

GNS3 topology for INE Workbook

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phpIPAM version 0.9 released

Dear all, I am happy to announce new version of phpipam IP address management – version 0.9.
New features, like Support for ICMP network discovery, ICMP check IP status in demand, Compressed (grouped) DHCP IP ranges and other were introduced. Most important are:

• Support for ICMP network discovery;
• Cron script to check status for selected subnets/hosts with threading suport (pcntl php extension required)
• ICMP check IP status in demand;
• Added folders;
• Compressed (grouped) DHCP IP ranges;
• Added subsections;

Some instructions on how to setup ICMP scanning will follow.

If you find phpIPAM useful for your company donations would be highly appreciated

You can demo it here: http://demo.phpipam.net/
You can download it on sourceforge site: phpipam-0.9.

Special thanks to all the people submitting bug reports, translators and feature testers!

Screenshots:

Full changelog for this release is:

New features:
----------------------------
+ Support for ICMP network discovery;
+ Cron script to check status for selected subnets/hosts with threading suport (pcntl php extension required);
+ ICMP check IP status in demand;
+ Compressed (grouped) DHCP IP ranges;
+ API server version 0.1;
+ Option to show and group subnets by VLAN in subnets list;
+ Option to show and Continue reading

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Out of the Mouths of Customers

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Plexxi – Optimized Workload and Workflow

Plexxi was a vendor that presented at Networking Field Day 6, and was one that really got me excited about what’s possible when you think about what kind of metadata your data center contains, and what products like Plexxi can do with that data once abstracted and normalized the right way. I will be intentionally brief with respect to my thoughts on the hardware - others like Ivan (and more) have already done a better job with this than I ever will.

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Plexxi – Optimized Workload and Workflow

Plexxi was a vendor that presented at Networking Field Day 6, and was one that really got me excited about what’s possible when you think about what kind of metadata your data center contains, and what products like Plexxi can do with that data once abstracted and normalized the right way. I will be intentionally brief with respect to my thoughts on the hardware - others like Ivan (and more) have already done a better job with this than I ever will.

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Plexxi – Optimized Workload and Workflow

Plexxi was a vendor that presented at Networking Field Day 6, and was one that really got me excited about what’s possible when you think about what kind of metadata your data center contains, and what products like Plexxi can do with that data once abstracted and normalized the right way. I will be intentionally brief with respect to my thoughts on the hardware - others like Ivan (and more) have already done a better job with this than I ever will.

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How Multi is MP-BGP in IOS-XR – Part #2

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Fixing high CPU use on Cisco 7600/6500

Recently some time ago (this blog post has also been lying in draft for a while) someone came to me with a problem they had with a Cisco 7600. It felt sluggish and "show proc cpu" showed that the weak CPU was very loaded.

This is how I fixed it.

"show proc cpu history" showed that the CPU use had been high for quite a while, and too far back to check against any config changes. The CPU use of the router was not being logged outside of what this command can show.

"show proc cpu sorted" showed that almost all the CPU time was spent in interrupt mode. This is shown after the slash in the first row of the output. 15% in this example:

  Router# show proc cpu sorted
  CPU utilization for five seconds: 18%/15%; one minute: 31%; five minutes: 42%
  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process 
  198   124625752 909637916        137  0.87%  0.94%  0.94%   0 IP Input         
  [...]
  

Interrupt mode CPU time is (a bit simplified and restricted to the topic at hand) used when the router has to react to some user traffic. Now why would the 7600 use the Continue reading

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Healthy Paranoia Show 18: Illusion, Lies and Neuroscience with Alex Stone

Ladies and gentleman, prepare to be mystified and amazed by another episode of Healthy Paranoia. Where even the unicorns are nerdy and the evil bit is always set on your packets.  Just in time for Halloween, get ready for some tricks and definitely  treats, because we’re going to discuss the intersection of magic, social engineering […]

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The post Healthy Paranoia Show 18: Illusion, Lies and Neuroscience with Alex Stone appeared first on Packet Pushers Podcast and was written by Mrs. Y.

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Next-hop resolution and point-to-point

I had this blog post lying around as a draft for a long time. I didn't think it was was "meaty" enough yet, but since I'm no longer a network consultant I don't think it'll become any meatier. So here it goes.

Here I will describe the process of L3-to-L2 mapping, or next-hop resolution and how it works with point-to-point circuits like PPP, ATM and Frame relay. It's the process of finding out what to actually do with a packet once the relevant routing table entry has been identified.

It's deceptively simpler than on a LAN segment, but since people generally learn Ethernet before they learn point-to-point nowadays I'm writing it anyway.

When a packet is to be sent to an address on the same subnet a L3-to-L2 mapping is done to look up the L2 destination address (if any) to apply.

The packet is then encapsulated in a L2 frame and sent out the interface.

On a normal Ethernet LAN segment ARP is used to look up L3-to-L2, and the frame will then have that (L2) MAC address as its destination. The frame will then be received by (and only by) the intended destination.

In a point-to-point interface there Continue reading

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Quiz #20 &#8211 NAT between Two Partner Companies

Your company has a border router (R2) that is connected to two partner companies: Partner-DB (R1) providing database services and Partner-APP (R3) that provides different application services to your web servers in DMZ (200.200.200.0/24). You are requested to configure NAT according to some requirements.

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I’m a Networking Guy, and I’m Here To Talk About Programming

I’m fortunate enough to work and be connected with some stellar networking professionals. I mean it - they’re rock stars. In my quest to surround myself with smart folks like this - in an attempt to at the very least learn by osmosis - I’ve clearly succeeded. I haven’t been in the industry for that long - but I’ve chosen networking (among other things) to be what I want to focus on professionally, and these are the best people to learn it from.

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I’m a Networking Guy, and I’m Here To Talk About Programming

I’m fortunate enough to work and be connected with some stellar networking professionals. I mean it - they’re rock stars. In my quest to surround myself with smart folks like this - in an attempt to at the very least learn by osmosis - I’ve clearly succeeded. I haven’t been in the industry for that long - but I’ve chosen networking (among other things) to be what I want to focus on professionally, and these are the best people to learn it from.

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Forwarding UDP broadcast traffic mechanisms

How does the internet work - We know what is networking

We will speak here about some basics about Forwarding UDP broadcast traffic. If you were wondering what Forwarding UDP broadcast traffic actually is I will try to explain it here in few words. If you have more that one broadcast domains in your local network, let’s say that you have three VLANs. In normal networking theory it’s normal […]

Forwarding UDP broadcast traffic mechanisms

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SearchSDN Article: Packet Design Pivots Route Analytics Toward SDN

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Spanning Tree Exercise and Revisiting Root Guard

This was actually spurned from a comment I received on another one of my blog posts that you can find here.  Seeing that comment, I white boarded it and realized that I may have been completely wrong in regards to how Root Guard could “break a network”. 

Let’s say we have the following topology:

• Core 1 is the root for VLAN 10 with a configured priority of 4096, and is the secondary root for VLAN 20 with a configured priority of 8192.  We alternate this with Core 2 in order to load balance VLAN traffic.
• Access 3 and 4 are left in default configuration regarding spanning tree.
• Two workstations are present – one in VLAN 10, and another in VLAN 20.  Their default gateways are SVIs that are on the Core switches.
• For simplicity, switch MAC addresses are the number contained in their names.  Example: Access 4’s MAC address is “4”.
• All link costs are the same.
• All links between switches are trunks transporting all VLANs.

Let’s work through the spanning tree topologies.

Core 1 – Root bridge for VLAN 10.  All ports designated.

Core 2 – Port 1 will be a root port Continue reading

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With SDN, Do We Still Need CCIEs?

"With SDN, we don't need CCIEs anymore. Anyone can run the network with a simple click-and-drag GUI." Really.

"SDN makes the knowledge of traditional networking is not relevant anymore. We need more people who can write code instead." Wow.

"SDN with Openflow removes all the current routing protocols. So why wasting your time to study CCIE?" Speechless.

Let's start with definition.

According to Wikipedia, SDN is "...an approach to building computer networks that separates and abstracts elements of these systems..." There are two important keywords there: separate, and abstraction. Separate means decouple Control Plane and Data/Forwarding Plane function. If in 'traditional networking' both Contol and Data functions are contained within a single device, SDN makes the separation so the Control plane can be moved to a device or system that is located at the central of the network. More intelligent control function that can see the whole network end-to-end.

And the Control plane can be customized, manipulated, re-programmed and so on, regardless the state of the Data plane. This is the first level of the abstraction.

Why is abstraction important? Because we want to separate the complexity. Think about building multiple layers that separate Continue reading