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Hedge 91: Leslie Daigle and IP Addresses Acting Badly

What if you could connect a lot of devices to the Internet—without any kind of firewall or other protection—and observe attackers trying to find their way “in?” What might you learn from such an exercise? One thing you might learn is a lot of attacks seem to originate from within a relatively small group of IP addresses—IP addresses acing badly. Listen in as Leslie Daigle of Thinking Cat and the Techsequences podcast, Tom Ammon, and Russ White discuss just such an experiment and its results.

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Free Speech is More than Words

A couple of weeks ago, I joined Leslie Daigle and Alexa Reid on Techsequences to talk about free speech and the physical platform—does the right to free speech include the right to build and operate physical facilities like printing presses and web hosting? I argue it does. Listen in if you want to hear my argument, and how this relates to situations such as the “takedown” of Parler.

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NATs, PATs, and Network Hygiene

While reading a research paper on address spoofing from 2019, I ran into this on NAT (really PAT) failures—

In the first failure mode, the NAT simply forwards the packets with the spoofed source address (the victim) intact … In the second failure mode, the NAT rewrites the source address to the NAT’s publicly routable address, and forwards the packet to the amplifier. When the server replies, the NAT system does the inverse translation of the source address, expecting to deliver the packet to an internal system. However, because the mapping is between two routable addresses external to the NAT, the packet is routed by the NAT towards the victim.

The authors state 49% of the NATs they discovered in their investigation of spoofed addresses fail in one of these two ways. From what I remember way back when the first NAT/PAT device (the PIX) was deployed in the real world (I worked in TAC at the time), there was a lot of discussion about what a firewall should do with packets sourced from addresses not indicated anywhere.

If I have an access list including 192.168.1.0/24, and I get a packet sourced from 192.168.2.24, Continue reading

Hedge 90: Andrew Wertkin and a Naïve Reliance on Automation

Automation is surely one of the best things to come to the networking world—the ability to consistently apply a set of changes across a wide array of network devices has speed at which network engineers can respond to customer requests, increased the security of the network, and reduced the number of hours required to build and maintain large-scale systems. There are downsides to automation, as well—particularly when operators begin to rely on automation to solve problems that really should be solved someplace else.

In this episode of the Hedge, Andrew Wertkin from Bluecat Networks joins Tom Ammon and Russ White to discuss the naïve reliance on automation.

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How Routers Really Work Live Webinar

I’m teaching a webinar on router internals through Pearson (Safari Books Online) on the 23rd of July. From the abstract—

A network device—such as a router, switch, or firewall—is often seen as a single “thing,” an abstract appliance that is purchased, deployed, managed, and removed from service as a single unit. While network devices do connect to other devices, receiving and forwarding packets and participating in a unified control plane, they are not seen as a “system” in themselves.

Register here.

Details and Complexity

What is the first thing almost every training course in routing protocols begin with? Building adjacencies. What is considered the “deep stuff” in routing protocols? Knowing packet formats and processes down to the bit level. What is considered the place where the rubber meets the road? How to configure the protocol.

I’m not trying to cast aspersions at widely available training, but I sense we have this all wrong—and this is a sense I’ve had ever since my first book was released in 1999. It’s always hard for me to put my finger on why I consider this way of thinking about network engineering less-than-optimal, or why we approach training this way.

This, however, is one thing I think is going on here—

The typical program aims to counter the inherent complexity of the decision by providing in-depth information. By providing such extremely detailed and complex information, these interventions try to enable people to make perfect decisions.

We believe that by knowing ever-deeper reaches of detail about a protocol, we are not only more educated engineers, but we will be able to make better decisions in the design and troubleshooting spaces.

To some degree, we think we are managing the Continue reading

Hedge 89: Dana Iskoldski and A House Divided

Bluecat, in cooperation with an outside research consultant, jut finished a survey and study on the lack of communication and divisions between the cloud and networking teams in deployments to support business operations. Dana Iskoldski joins Tom Ammon and Russ White to discuss the findings of their study, and make some suggestions about how we can improve communication between the two teams.

Please find a copy of the study at http://bluecatnetworks.com/hedge.

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The Hedge 88: Todd Palino and Getting Things Done

I often feel like I’m “behind” on what I need to get done. Being a bit metacognitive, however, I often find this feeling is more related to not organizing things well, which means I often feel like I have so much to do “right now” that I just don’t know what to do next—hence “processor thrashing on process scheduler.” Todd Palino joins this episode of the Hedge to talk about the “Getting Things Done” technique (or system) of, well … getting things done.

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It’s Most Complicated than You Think

It’s not unusual in the life of a network engineer to go entire weeks, perhaps even months, without “getting anything done.” This might seem odd for those who do not work in and around the odd combination of layer 1, layer 3, layer 7, and layer 9 problems network engineers must span and understand, but it’s normal for those in the field. For instance, a simple request to support a new application might require the implementation of some feature, which in turn requires upgrading several thousand devices, leading to the discovery that some number of these devices simply do not support the new software version, requiring a purchase order and change management plan to be put in place to replace those devices, which results in … The chain of dominoes, once it begins, never seems to end.

Or, as those who have dealt with these problems many times might say, it is more complicated than you think. This is such a useful phrase, in fact, it has been codified as a standard rule of networking in RFC1925 (rule 8, to be precise).

Take, for instance, the problem of sending documents through electronic mail—in the real world, there are various Continue reading

The Hedge 87: Jordan Holand and nPrint

The network monitoring world is rife with formats for packets being measured—every tool has its own format. What would make things a lot better for network engineers is a standard data representation for packet analysis, no matter what format packets are captured in. Jordan Holland joins Russ White and Tom Ammon on this episode of the Hedge to discuss the problem and nprint, a standard packet analysis format and tools for converting from other formats.

You can find out more about nprint here.

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The Hedge 86: TCPLS

TCP and QUIC are the two primary transport protocols in use on the Internet today—QUIC carries a large part of the HTTP traffic that makes the web work, while TCP carries most everything else that expects reliability. Why can’t we apply the lessons from QUIC to TCP so we can merge these two protocols, unifying Internet transport? TCPLS is just such an attempt at merging the most widely used reliable transport protocols.

You can read more about TCPLS here.

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