Pinging Hosts Sequentially vs Concurrently in Python

I’m reorganizing some things in my homelab and wanted to check how many hosts are alive in a /24. The simple check, while not perfect, is to ping all the hosts and see who responds. I used Claude to generate some Python for me and noticed it used some tools I had not used before, to run code concurrently, which really speeds up things like scanning a /24 for alive hosts. In this post I’ll compare running sequentially vs concurrently and break down the code.

Running something sequentially means that every job, such as checking if an IP is alive, must run to completion before the next job starts. This is highly inefficient, of course, mainly for two reasons:

  • Work can’t be performed in parallel
  • Most of the time is spent waiting, rather than working

Especially when the job involves something like ping, we must give hosts a reasonable time to respond, so we’ll wait up to a second. We also can’t one-shot the ping because what if we have no ARP entry for the host we are pinging (assuming same subnet)? Then, a host that is alive could be reported as dead due to the missing ARP entry.

I’ll Continue reading

Goodbye, Leaf-and-Spine Networks?

A friend of mine sent me links to a new paper published by AWS engineers, and an associated LinkedIn post which claims:

We got lean, resilient, massive aggregation fabrics that provide 33% better throughput with 69% fewer routers, savings 27% of costs, cutting power usage by 40%, and reducing CO2 emissions.

The obvious question one should ask after reading the hyperventilated Radical Network Redesign blog post is thus: is this the end of leaf-and-spine networks? Of course not. Let’s go into the details.

Read more …

Blogging with an LLM assistant

AI slop is invading the web. A recent story about disallowing LLM-generated submissions on Lobsters triggered a lot of debate. My personal worst offenders are LinkedIn articles with AI-generated images and uninspired articles filled with emojis from people trying to masquerade as experts on a subject they don’t care enough to write themselves. While I am unhappy about this situation, I rely on LLMs for grammar, copyediting, and translation. I don’t see this as a contradiction.

I am a native French speaker, but I blog in both English and French. When I started writing this blog in 2011, I was composing in French and translating to English, but I found it was better to work in the reverse order to avoid unnatural and non-idiomatic constructions. One of my goals is to write “good” English but I never felt it was my strong point.1 For example, verb tenses are often an issue, even if I mostly stick with the present tense. I learn the rules and forget them right away. I also don’t feel like hiring an editor for something I see as an hobby.

As an example, I have kept the history of the Continue reading

PP113: Patch Gaps, Pretexting, and AI Use for Crimes and Crimefighting: 2026 Verizon DBIR Highlights

The Verizon Data Breach Investigations Report (DBIR) is a postmortem of a year’s worth of cyber incidents and breaches, and a snapshot of how well organizations are responding to actual threats. Drew and JJ share highlights from the 2026 installment, including: For the first time, vulnerability exploits top the list for initial access What a... Read more »

Installing GitLab Community Edition

I need an on-premises Git server for my labbing so this post will describe how to install GitLab Community Edition (CE). My install is on Ubuntu 24.04 LTS, specifically ubuntu-24.04.4-live-server-amd64, but you can use whatever works for you.

First I upgrade all the packages:

sudo apt update && sudo apt upgrade -y

Then install the dependencies for GitLab CE:

sudo apt install ca-certificates curl openssh-server postfix tzdata perl

In the installation for postfix, select Internet Site and then enter the server’s domain name. This is really only if you need to send e-mails.

Then reboot:

sudo reboot

I configure the hostname of the server:

sudo hostnamectl set-hostname gitlab.lab.local

I’ll update this later when installing a certificate for the server.

Then download the script that will add GitLab’s package repository to the system’s apt sources:

curl https://packages.gitlab.com/install/repositories/gitlab/gitlab-ce/script.deb.sh | sudo bash

Next we setup the EXTERNAL_URL environment variable and install version 18.4 (I needed this specific version):

sudo EXTERNAL_URL="http://gitlab.lab.local" apt install -y gitlab-ce=18.4.*

The EXTERNAL_URL variable is read by the GitLab installer and this is the URL that the server will be available via. I’ll update Continue reading

Worth Reading: Genie Tarpit

Following a link in Martin Fowler’s Fragments, I stumbled upon Genie Tarpit by Kent Beck – a perfect summary of my experiences with AI coding (code reviews are OK, new code less so). He also provided a good reason for that behavior:

The “plausible deniability” task orientation of the genie leaves it claiming success even though the code doesn’t work at all.

And the proposed solution?

You probably saw this one coming—nobody knows.

Read more …

Defend against frontier cyber models: Cloudflare’s architecture as customer zero

A few weeks ago, we wrote about Project Glasswing and what we observed when we pointed cyber frontier models at our own code. Since then, we’ve seen that the part of the post that has resonated most deeply is the argument that the architecture around the vulnerability matters more than the speed of the patch.

In the conversations we've had with CISOs and security teams since, the questions have been consistent: what does our architecture actually look like, what should we monitor for, where do we start, and how can Cloudflare help?

Before getting into the details: the architecture below is built almost entirely from Cloudflare's own products, because Cloudflare security is customer zero for the security products we build. The Cloudflare stack already exists in front of our code, employees, and customer-facing applications. If you're a Cloudflare customer, every layer below is available to you today. If you're not, the principles still apply to whatever stack you've built.

What a cyber frontier model actually changes

In the previous post, we showed how a cyber frontier model like Mythos changes the attacker’s timeline. It can find vulnerabilities, reason through exploit chains, and generate working proofs faster than earlier models. Continue reading

NB578: Cisco Goes All-In on AI Ops with Cloud Control; China Floats Underwater Data Center

Take a Network Break! Our Red Alert covers a critical Android vulnerability that could lead to local privilege escalation to root. On the news front, we dig into Cloud Control, Cisco’s ambitious AI ops platform that spans its networking, security, compute, observability, and collaboration portfolios. We also talk about Cisco Live Protect, which provides pre-patch... Read more »

Worth Reading 060826


In a paper published late in 2025, Østergaard and colleagues reported on their examination of almost 40 psychiatric referrals across Denmark that implicated AI chatbots in harmful interactions, including suicidal thoughts, eating disorders, and fostering delusions

 


Since its deployment in 2011, the adoption of RPKI by Internet Service Providers has shown continuous growth, a trend that persists to this day. As this growth continues it is important to measure its effect on BGP stability.

 


AI companies, AI influencers and famous professors have been making extraordinary claims for years about AI.

 


A robotic system that can produce a rubbery pancake is a true technical and logistic achievement, but why all this work to automate the production of mediocrity?

 


The greatest risk we face today isn’t that AI is becoming “too smart”; it’s that we are beginning to treat this technology as an infallible “oracle” rather than a capable, yet fundamentally fallible, “intern.”

Turning Cloudflare’s threat indicators into real-time WAF rules

Cloudflare’s Threat Events provides security analysts with a window into the global threat landscape. The platform offers a peek into the immense traffic that Cloudflare processes every day, so you can see in real time which IPs are attacking specific industries or which threat actors are trending globally. However, translating that visibility into active mitigation has often been a manual, reactive process.

Security teams have faced a recurring frustration: knowing that certain IP addresses were associated with specific threat actors (like Tycoon 2FA or RaccoonO365) or had been seen targeting their specific industry in other regions, but they couldn't easily automate the blocking of these high-risk IPs within their own WAF unless they manually configured the rules. 

We are excited to announce a new integration that brings Cloudflare’s vast threat intelligence directly into your WAF engine: you can now write proactive rules using live intelligence data. This means you can add more intelligence context to protect your application against known bad actors — before they even attempt to touch your infrastructure.

By populating specialized fields during the early stages of a request, the WAF can now screen traffic based on:

netlab 26.06: OSPFv3 on FortiOS, MPLS/VPN on SR Linux

netlab release 26.06 adds OSPFv3 support on FortiOS (by @a-v-popov) and MPLS/VPN support on SR Linux. We also ensured the installation scripts work on Ubuntu 26.04 (everything else was OK) and updated the installed Vagrant version to 2.4.9 (we’re not using new Vagrant features; you don’t have to upgrade it in an existing installation).

Other than that, we added a few improvements and squashed a number of bugs.

Upgrading or Starting from Scratch?

Evolusi Teknologi Energy Buffer untuk Efisiensi Kendaraan Masa Depan

Di tengah percepatan inovasi otomotif, teknologi kendaraan terus mengalami perkembangan signifikan untuk mendukung efisiensi energi dan keberlanjutan. Salah satu terobosan yang mulai populer adalah energy buffer berbasis teknologi pintar yang mampu mengelola energi secara optimal dalam kendaraan masa depan. Artikel ini akan membahas evolusi teknologi intelligent energy buffer dan peran vitalnya dalam transformasi kendaraan modern.

Apa Itu Energy Buffer?

Energy buffer adalah sistem penyimpanan energi sementara yang berfungsi untuk menstabilkan dan mengoptimalkan distribusi energi pada kendaraan. Sistem ini membantu dalam menyimpan energi saat kelebihan daya dan melepaskannya kembali saat kebutuhan energi meningkat, sehingga memastikan konsumsi yang lebih efisien dan mengurangi pemborosan energi.

Dalam konteks kendaraan, energy buffer biasanya diintegrasikan dengan baterai utama dan sistem regenerasi energi, seperti pengereman regeneratif pada kendaraan listrik dan hybrid. Fungsi utamanya adalah meningkatkan performa kendaraan sekaligus mengurangi emisi.

Peran Teknologi Kendaraan dalam Meningkatkan Efisiensi Energi

Seiring perkembangan teknologi kendaraan, kebutuhan untuk mengoptimalkan penggunaan energi semakin mendesak. Energi yang efisien tidak hanya mengurangi konsumsi bahan bakar tetapi juga memperpanjang umur kendaraan dan komponen pendukungnya.

Intelligent energy buffer hadir sebagai solusi cerdas dengan fitur-fitur seperti:

  • Manajemen Energi Otomatis: Mengatur aliran energi secara real-time sesuai kebutuhan pengemudi dan kondisi jalan.
  • Integrasi dengan Sistem Kendaraan Lain: Berfungsi bersama ECU Continue reading

Potensi Industri Produk Turunan Singkong untuk Meningkatkan Ekonomi Desa

Singkong merupakan salah satu tanaman pangan yang memiliki peranan penting dalam ketahanan pangan di Indonesia. Selain mudah dibudidayakan, singkong juga tahan terhadap berbagai kondisi lingkungan, sehingga sangat potensial untuk dikembangkan sebagai bahan baku industri pangan. Dalam beberapa tahun terakhir, industri produk olahan singkong mulai menunjukkan perkembangan yang signifikan, memberikan peluang besar untuk meningkatkan nilai tambah dan mendongkrak ekonomi desa.

Mengapa Singkong Menjadi Bahan Baku Unggulan?

Singkong memiliki banyak keunggulan dibandingkan dengan tanaman pangan lainnya:

  • Ketersediaan melimpah: Singkong dapat tumbuh hampir di seluruh wilayah Indonesia, termasuk daerah-daerah dengan kondisi tanah kurang subur.
  • Mudah diolah: Singkong dapat diolah menjadi berbagai produk olahan yang bernilai jual tinggi.
  • Nilai gizi yang baik: Sebagai sumber karbohidrat, singkong juga kaya akan serat dan beberapa jenis mineral.
  • Tahan lama: Produk olahan singkong biasanya memiliki masa simpan lebih lama dibandingkan singkong segar.

Karena alasan di atas, singkong sangat potensial untuk diangkat menjadi bahan baku utama dalam industri pangan yang dapat memberikan dampak positif bagi perekonomian lokal.

Ragam Produk Olahan Singkong dalam Industri Pangan

Industri produk turunan singkong telah berkembang cukup luas dengan berbagai inovasi produk olahan yang menarik, antara lain:

  • Tepung singkong: Digunakan sebagai bahan baku pengganti tepung terigu, terutama bagi yang alergi Continue reading

Best of the Hedge: Episode 15, Supporting Open Source

Many companies rely on open source, regardless of whether or not they realize it. In this best of the Hedge episode, Alistair Woodman joins Russ White and Tom Ammon to talk about not only why you should support the open source projects you use, but how you can.
 

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Reposting a classic episode this week because I was out of town and didn’t get around to editing an episode.

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