Leaky Abstractions

Much of our life, as engineers, is about building, manipulating, and using abstractions. For instance, C is nothing but an abstraction on top of the actual register set provided by a particular processor. HTML is nothing but an abstraction for formatting and display (a markup language), implemented in — well, C. There is a lot of power in such abstractions, of course. Without them we couldn’t build operating systems, applications, browsers, web pages — or networks.

Ethernet is an abstraction of electronic signals (anyone remember Manchester Encoding?). IP is an abstraction of every physical layer in the world. TCP is an simulation, or abstraction, of a reliable connection oriented link over (completely unreliable) IP. HTTP is an abstraction of a flow of information, a stream, between two computers. It’s all abstractions — as the philosopher might say, “it’s abstractions all the way down.” So what’s wrong with this?

All abstractions are leaky. What do I mean when I say abstractions are leaky? Let’s turn to the originator of the phrase, Joel Spolsky:

Abstractions fail. Sometimes a little, sometimes a lot. There’s leakage. Things go wrong. It happens all over the place when you have abstractions.

This is the Continue reading

VMware NSX: a short introduction and HOWTO install it

NSX is the SDN solution by VMware. NSX is  available as: NSX for vSphere (NSX-V) NSX Multi-Hypervisor (NSX-MH) NSX-MH is NSX for Multi Hypervisors (ESXi, KVM, Xen, Hyper-V). This post is focused on NSX-V. Acronyms DFW: Distributed FireWall DLR: Distributed Logical Router LIF: Logical InterFace UWA: User World Agent VDS: VSphere Distributed Switch VIB: VSphere Installation Bundle VNID: VXLAN […]

Switching is not working on VMware NSX

In this scenario we have three VMs deployed on a NSX vSwitch with VNI 5002. Two are running on the same hosts and they can ping each other, the other one is running on a separated host and cannot ping the other VMs. Check if at least one interface is configured for VXLAN: ~ # […]

A Call for Better Vulnerability Response

Microsoft forced a self-serving vulnerability disclosure policy on the industry 10 years ago, but cries foul when Google does the same today.

Ten years ago, Microsoft dominated the cybersecurity industry. It employed, directly or through consultancies, the largest chunk of security experts. The ability to grant or withhold business meant influencing those consulting companies -- Microsoft didn't even have to explicitly ask for consulting companies to fire Microsoft critics for that to happen. Every product company depended upon Microsoft's goodwill in order to develop security products for Windows, engineering and marketing help that could be withheld on a whim.

This meant, among other things, that Microsoft dictated the "industry standard" of how security problems ("vulnerabilities") were reported. Cybersecurity researchers who found such bugs were expected to tell the vendor in secret, and give the vendor as much time as they needed in order to fix the bug. Microsoft sometimes sat on bugs for years before fixing them, relying upon their ability to blacklist researchers to keep them quiet. Security researchers who didn't toe the line found bad things happening to them.

I experienced this personally. We found a bug in a product called TippingPoint that allowed us to decrypt their Continue reading

PQ Show 41 – HP Networking’s Sarwar Raza on the Meaning of Open

This sponsored podcast is a continuation of our series recorded at HP Discover Barcelona 2014. Our thanks to Chris Young for organizing the topics and guests. The interesting conversations in Barcelona at HP Discover 2014 continued with a chat about the shifty meaning of “open.” In the world of technology, being open means a lot of different […]

Author information

Ethan Banks

Co-host at Packet Pushers

Ethan Banks, CCIE #20655, has been managing networks for higher ed, government, financials and high tech since 1995. Ethan co-hosts the Packet Pushers Podcast, which has seen over 3M downloads and reaches over 10K listeners. With whatever time is left, Ethan writes for fun & profit, studies for certifications, and enjoys science fiction. @ecbanks
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The post PQ Show 41 – HP Networking’s Sarwar Raza on the Meaning of Open appeared first on Packet Pushers Podcast and was written by Ethan Banks.

BGPSEC: Leaks and Leaks

This is the final post in my series on BGPSEC — I will probably follow this up, at some point, with a couple of posts on some alternatives to BGPSEC, and the larger issue of the evolution of BGP. Basic Operation Protections Offered Replays, Timers, and Performance Signatures and Performance In this final post, I […]

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Russ White

Principal Engineer at Ericsson

Russ White is a Network Architect who's scribbled a basket of books, penned a plethora of patents, written a raft of RFCs, taught a trencher of classes, and done a lot of other stuff you either already know about — or don't really care about. You can find Russ at 'net Work, the Internet Protocol Journal, and his author page on Amazon.
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The post BGPSEC: Leaks and Leaks appeared first on Packet Pushers Podcast and was written by Russ White.

Taming Netlink

Netlink is a Linux Kernel interface that is used to talk Networking between Kernel processes, or from userland to Kernel processes. This post documents how I tamed Netlink and make working with it in Golang easier.

If you want to create an interface, set an MTU, set an IP address …

Taming Netlink

Netlink is a Linux Kernel interface that is used to talk Networking between Kernel processes, or from userland to Kernel processes. This post documents how I tamed Netlink and make working with it in Golang easier.

If you want to create an interface, set an MTU, set an IP address etc... on a Linux machine then you have to talk Netlink to do it. For Golang, there are a number of libraries, but this one seems to be gaining a lot of traction recently. Honorable mentions go to Tenus and Docker's libcontainer.

Now, this library is good, but it isn't complete and some of the behavior I need is missing. So how does one go about implementing it you might ask?

Here's my process:

1. Browse the iproute2 source code

The iproute2 utility is insanely useful - it replaces ifconfig and route for those with memories long enough. In my case, the feature I wanted was here and I could take a look at the exact message structure required :)

2. Debugging Netlink

Once I'd written my tests and code, I wasn't surprised to see that things were not working. strace will get you part of the way, but it's Continue reading

Taming Netlink

Netlink is a Linux Kernel interface that is used to talk Networking between Kernel processes, or from userland to Kernel processes. This post documents how I tamed Netlink and make working with it in Golang easier.

Unique RD per PE in MPLS VPN for Load Sharing and Faster Convergence

This post describes how load sharing and faster convergence in MPLS VPNs is possible by using an unique RD per VRF per PE. It assumes you are already familiar with MPLS but here is a quick recap.

The Route Distinguisher (RD) is used in MPLS VPNs to create unique routes. With IPv4, an IP address is 32 bits long but several customers may and probably will use the same networks. If CustomerA uses 10.0.0.0/24 and CustomerX also uses 10.0.0.0/24, we must in some way make this route unique to transport it over MPBGP. The RD does exactly this by prepending a 64 bit value and together with the IPv4 address, creating a 96-bit VPNv4 prefix. This is all the RD does, it has nothing to do with the VPN in itself. It is common to create RD consisting of AS_number:VPN_identifier so that a VPN has the same RD on all PEs where it exists.

The Route Target (RT) is what defines the VPN, which routes are imported to the VPN and the topology of the VPN. These are extended communities that are tagged on to the BGP Update and transported over MPBGP.

MPLS uses Continue reading

Headwinds, or Uphill?

As some of my readers know, I’ve done a fair bit of bike touring. Two of the challenges of bike touring are riding uphill, and riding into headwinds.

Riding uphill is tough. 2,300m passes in snow, or 3,200m passes in sunshine, it’s tough going. But you put your head down, and keep turning the pedals, because you know that eventually you will reach the top, and there will be a downhill reward.

Riding into headwinds is a different story. You can battle into headwinds for days, and never get any reward. It saps your energy, and you don’t know if or when it will ever end. The wind could just keep coming from that direction. I’ve gone to different countries just to avoid the wind in the past.

They’re both hard. But one of them has an end, and a reward. The other one can just keep on sucking away your will to live.

Applying it to Life

This applies to the rest of your life. The tricky bit is that sometimes you don’t know if you’re going uphill, or into the wind. Both of them feel hard, and you can’t always see the end in sight.

A Continue reading

Raspberry Pi RSPAN Capture Box

For some time I have had issues while doing captures such as finding the elusive “spare laptop” you can use, multiple trips out to the site to pick up the captures, or finding another NIC to put in there so you can connect remotely and copy the captures over the network, taking up 2 switch […]

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Daniel Himes

Daniel Himes grew up in the country without power or running water, and yet somehow fell into IT, and from there into networking. He learned how to do his job by getting certifications till his resume looked like he is a Cisco salesman. Over at dhimes.com he has a few tools he came up with, however just a warning you’ll note on his linkedin page he makes no claim to being good at web-pages.
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The post Raspberry Pi RSPAN Capture Box appeared first on Packet Pushers Podcast and was written by Daniel Himes.

I became CCIE# 46173

How does Internet work - We know what is networking

This is the story on how I became CCIE# 46173 To be honest, when I look back, I do not really know the main reason behind going through all this trouble, but I can tell you the story about how I did it. It’s mostly a thriller, and some drama towards the end. I will give you an overview of the whole process including the materials used, videos watched, books read and struggles that I went through. I think that is the right thing to do. This article is for all of you out there who are still trying to study for this exam and need some suggestions.

I became CCIE# 46173

Pick a Topic for NSX Deep Dive Software Gone Wild Episode

Dmitri Kalintsev, one of the networking guys from VMware NSX team, has kindly agreed to do an NSX technical deep dive Software Gone Wild episode… and you have the opportunity to tell him what you’d like to hear. It’s as easy as writing a comment, and we’ll pick one of the most popular topics.

Do keep in mind that we plan to do a technical deep dive, and it has to fit within an hour or so or nobody will ever listen to it, so please keep your suggestions focused. “Troubleshooting NSX”, “NSX Design”, or “NSX versus ACI ” is not what we’re looking for ;)

Network Field Day 9

I had a fantastic time at Network Field Day 8, and now I’ve been lucky enough to be invited back to NFD9 this February.

As usual, the Tech Field Day crew have put together a great mix of vendors. I particularly like the look of the SDN WAN-focused vendors, such as VeloCloud and cloudgenix. Much of the early SDN focus has been on the DC use-case, but that has limited applicability in my local market. SDN WAN solutions definitely apply to the New Zealand market though. I can think of several organisations where I’d love to have better WAN options today.

I’m also very happy to see Cumulus Networks making a first appearance.  I’ve done a lot of Linux work during my career, and there’s many times I would have loved to have all the capabilities of a GNU/Linux environment on a switch. I think they will have a huge influence on how Network OSes are delivered in future.

Network Management has always been a large part of my career too, so I’m looking forward to hearing updates from SolarWinds, and to find out more about NetBeez.

There’s some old faces and new attending. I’m looking forward to meeting people who I’ve Continue reading

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