AWS Security Groups, NACL and ENI

AWS Security Groups, NACL and ENI

This is the third blog post in the AWS Networking series. If you have been following along, you can continue with the lab we have built so far. For anyone who has just landed on this page, you can still follow along as long as you are already familiar with the basics of AWS networking. If you are completely new, however, I highly recommend checking out the introductory posts linked below to get up to speed.

In this blog post, we will look at AWS Security Groups, Network ACL (NACL) and Elastic Network Interfaces (ENI).

AWS Networking Fundamentals
If you’re brand new to AWS, don’t worry. This post focuses on the basics of AWS networking. General networking knowledge is helpful but not required - I’ll try to explain things clearly so everyone can follow along.
AWS Security Groups, NACL and ENIPacketswitchSuresh Vina
AWS Security Groups, NACL and ENI
AWS NAT Gateway and Private/Public Subnets
When working with AWS networking, you will often hear the terms ‘public subnet’ and ‘private subnet’. However, if you go into the AWS console to create a subnet, you won’t find any option to explicitly make it one or the other.
AWS Security Groups, NACL and ENIPacketswitchSuresh Vina
AWS Security Groups, NACL and ENI

AWS Security Groups

So far, we have briefly touched on Security Continue reading

AWS NAT Gateway and Private/Public Subnets

AWS NAT Gateway and Private/Public Subnets

When working with AWS networking, you will often hear the terms 'public subnet' and 'private subnet'. However, if you go into the AWS console to create a subnet, you won't find any option to explicitly make it one or the other. So, what exactly makes a subnet public or private?

In this blog post, we will look at the differences between public and private subnets, see how they are defined by their routing, and understand how the AWS NAT Gateway fits into this architecture.

If you are completely new to AWS networking and want to learn the basics of setting up a VPC, feel free to check out my previous post linked below.

AWS Networking Fundamentals
If you’re brand new to AWS, don’t worry. This post focuses on the basics of AWS networking. General networking knowledge is helpful but not required - I’ll try to explain things clearly so everyone can follow along.
AWS NAT Gateway and Private/Public SubnetsPacketswitchSuresh Vina
AWS NAT Gateway and Private/Public Subnets

Public vs Private Subnets

The key difference between a 'public' and a 'private' subnet is simply its route to the Internet. It is not an inherent setting of the subnet itself, but a behaviour defined by the route table associated Continue reading

Worth Reading 062325


asically, model collapse happens when the training data no longer matches real-world data, leading the new LLM to produce gibberish, in a 21st-century version of the classic computer aphorism “garbage in, garbage out.”


As AI workloads scale to thousands of accelerators, the interconnect fabric (also known as a scale-up fabric) for rack-scale systems is under intense scrutiny. Significant advancements are reshaping scale-up connectivity in 2025.


Standardized in 2021, QUIC is a UDP-based protocol designed to improve upon the TCP / TLS stack. While the QUIC protocol recommends pacing, and congestion control algorithms like BBR rely on it, the user-space nature of QUIC introduces unique challenges.


According the Google Cloud’s mini incident report, the issue occurred due to an invalid automated quota update to the API management system, which was distributed globally, causing external API requests to be rejected.


The specification details enhancements to Ethernet that improve low-latency transport in high-throughput networking deployments. It includes a modern Remote Direct Memory Access (RDMA) approach, direct memory access implementations, transport protocols, and congestion control mechanisms.

Static Routes in netlab Lab Topologies

As much as we’d love everything in our networks to be dynamic, auto-configured, or software-defined, reality often intervenes and forces us to use static routes, so we needed a mechanism to specify them in netlab lab topologies.

A static route has two components: the destination prefix and the next hop – the device that we hope knows how to reach that destination. The next hop is usually specified as an IPv4 or IPv6 address, but may also include outgoing interface information1.

Read more …

Setting clock source with GNU Radio

I bought a GPS Disciplined Oscillator (GPSDO), because I thought it’d be fun for various projects. Specifically I bought this one.

I started by calibrating my ICOM IC-9700. I made sure it got a GPS lock, and connected it to the 9700 10MHz reference port, with a 20dB attenuator inline, just in case. Ok, the receive frequency moved a bit, but how do I know it was improved? My D75 was still about 200Hz off frequency.

IC9700 screenshot showing D75

Segal’s law parahrased: “Someone with one radio knows what frequency they’re on. Someone with two radios is never sure”.

Unless, of course, that person has two radios with disciplined oscillators. Which I do. I also have a USRP B200 with an added GPSDO accessory.

Sidenote: wow, that’s gotten expensive. Today I’d probably use the same GPSDO from DXPatrol instead. Note that if you do have the GPSDO installed in the B200, then you cannot use an external 10MHz reference. It’s a known issue. Then again if you paid this much, why would you not use it?

Configuring GNU Radio to use the GPSDO

First I thought that surely the best reference would be the default, so I should be able to just send Continue reading

Software defined KISS modem

I’ve kept working on my SDR framework in Rust called RustRadio, that I’ve blogged about twice before. I’ve been adding a little bit here, a little bit there, with one of my goals being to control a whole AX.25 stack.

As seen in the diagram in this post, we need:

  1. Applications, client and server — I’ve made those.
  2. AX.25 connected mode stack (OSI layer 4, basically) — The kernel’s sucks, so I made that too.
  3. A modem (OSI layer 2), turning digital packets into analog radio — The topic of this post.

The job of the modem

Applications talk in terms of streams. AX.25 implementation turns that into individual data frames. The most common protocol for sending and receiving frames is KISS.

I’ve not been happy with the existing KISS modems for a few reasons. The main one is that they just convert between packets and audio. I don’t want audio, I want I/Q signals suitable for SDRs.

On the transmit side it’s less of a problem for regular 1200bps AX.25, since either the radio will turn audio into a FM-modulated signal, or if using an SDR it’s trivial to add the audio-to-I/Q step.

Continue reading

HN786: From Intent-Based to Autonomous Ops With Cisco Crosswork and Provider Connectivity Assurance (Sponsored)

Service provider networks face a couple of difficult challenges: how to map service level agreements to actual network health and performance, and how to deliver service assurance to customers regardless of what happens on the network. On today’s sponsored Heavy Networking we talk with Cisco Systems about its approach to service assurance, how Cisco is... Read more »

Palo Alto Create Bulk Address Objects using Pan-OS Python SDK

Palo Alto Create Bulk Address Objects using Pan-OS Python SDK

In this blog post, we'll see how to configure bulk Address-Objects at once and then add them to an Address-Group using the pan-os-python Library. If you haven't used the pan-os-python library before, have a look at my other blog post to learn more.

Palo Alto PAN-OS SDK for Python
Let’s start learning the pan-os-python library with a simple script. This script will be our foundation, and it’s as straightforward as it gets, creating a basic firewall rule on a Palo Alto firewall.
Palo Alto Create Bulk Address Objects using Pan-OS Python SDKPacketswitchSuresh Vina
Palo Alto Create Bulk Address Objects using Pan-OS Python SDK

Methods we will use

Here is the official guide for the useful methods

  1. add() - This method is used to add an object as a child of another object. In our scenario, it's for adding an Address Object to the firewall or panorama object.
  2. extend() - This method allows you to add a list of objects as children. In our context, it means adding a 'list' of Address objects to the firewall or panorama object.
  3. create() - Once you've defined an object in the script, the create() method is used to push this object to the live device, making the configuration active.
  4. create_similar() - This method pushes objects of the same type to the live Continue reading

Everything you need to know about NIST’s new guidance in “SP 1800-35: Implementing a Zero Trust Architecture”

For decades, the United States National Institute of Standards and Technology (NIST) has been guiding industry efforts through the many publications in its Computer Security Resource Center. NIST has played an especially important role in the adoption of Zero Trust architecture, through its series of publications that began with NIST SP 800-207: Zero Trust Architecture, released in 2020.

NIST has released another Special Publication in this series, SP 1800-35, titled "Implementing a Zero Trust Architecture (ZTA)" which aims to provide practical steps and best practices for deploying ZTA across various environments.  NIST’s publications about ZTA have been extremely influential across the industry, but are often lengthy and highly detailed, so this blog provides a short and easier-to-read summary of NIST’s latest guidance on ZTA.

And so, in this blog post:

  • We summarize the key items you need to know about this new NIST publication, which presents a reference architecture for Zero Trust Architecture (ZTA) along with a series of “Builds” that demonstrate how different products from various vendors can be combined to construct a ZTA that complies with the reference architecture.

  • We show how Cloudflare’s Zero Trust product suite can be integrated with offerings from other vendors Continue reading

Defending the Internet: how Cloudflare blocked a monumental 7.3 Tbps DDoS attack

In mid-May 2025, Cloudflare blocked the largest DDoS attack ever recorded: a staggering 7.3 terabits per second (Tbps). This comes shortly after the publication of our DDoS threat report for 2025 Q1 on April 27, 2025, where we highlighted attacks reaching 6.5 Tbps and 4.8 billion packets per second (pps). The 7.3 Tbps attack is 12% larger than our previous record and 1 Tbps greater than a recent attack reported by cyber security reporter Brian Krebs at KrebsOnSecurity.

New world record: 7.3 Tbps DDoS attack autonomously blocked by Cloudflare

The attack targeted a Cloudflare customer, a hosting provider, that uses Magic Transit to defend their IP network. Hosting providers and critical Internet infrastructure have increasingly become targets of DDoS attacks, as we reported in our latest DDoS threat report. Pictured below is an attack campaign from January and February 2025 that blasted over 13.5 million DDoS attacks against Cloudflare’s infrastructure and hosting providers protected by Cloudflare.

DDoS attack campaign target Cloudflare infrastructure and hosting providers protected by Cloudflare

Let's start with some stats, and then we’ll dive into how our systems detected and mitigated this attack.

The 7.3 Tbps attack delivered 37.4 Continue reading

Intel Starts Re-Engineering Its Executive Ranks

It has been two and a half months since new chief executive officer Lip-Bu Tan gave the keynote at Intel’s Vision 2025 event, and the company has been relatively quiet by its own standards over the past several decades as Tan gets the lay of the land and tries to plot out the course of the company to rebuild its foundry business and reorient and focus its chip design and sales business. …

Intel Starts Re-Engineering Its Executive Ranks was written by Timothy Prickett Morgan at The Next Platform.

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