Use socat to check that IPFIX is being received (IANA assigned port for IPFIX is 4739):
socat -b 0 -dd -u UDP6-RECV:4739 - 2>&1Output demonstrates that at least some IPFIX messages can be received when listening on port 4739.
2026/05/15 22:46:32 socat[108419] N using stdout for writing 2026/05/15 22:46:32 socat[108419] N starting data transfer loop with FDs [5,5] and [1,1] 2026/05/15 22:46:33 socat[108419] N received packet with 0 bytes from AF=10 [fec0:0000:0000:0000:0001:000c:2744:69f1]:50978 2026/05/15 22:46:33 socat[108419] N received packet with 0 bytes from AF=10 [fec0:0000:0000:0000:0001:000c:2744:69f1]:50978Use tcpdump to check for IPFIX packets. This gives visibility into packets before the host network stack, so you can see packets before they are dropped by host network stack or host firewall
tcpdump -i enp0s3 -n udp port 4739The output shows that IPFIX datagrams are being received from a second source, fec0::1:c:2744:69f0, but they aren't showing up in the socat output, so the Linux kernel must be dropping them for some reason.
dropped privs to tcpdump tcpdump: verbose output suppressed, use -v[v]... for full protocol decode listening on enp0s3, link-type EN10MB (Ethernet), snapshot length 262144 bytes 21:09:57.217821 Continue reading
Cloudflare and Anthropic have collaborated to integrate Claude Managed Agents with Cloudflare Sandboxes. Our new integration gives you more control over your agent sandboxes, secures connections to private services, and improves observability.
In the past year, Cloudflare’s Developer Platform has expanded to give more developers the tools they need to run agents at scale. This includes:
Sandboxes for full stateful Linux microVMs at scale
Agents SDK, providing simple and customizable agent framework
Browser Run, which gives agents fully programmable and observable browsers
Dynamic Workers, allowing for dynamic sandboxed code execution at massive scale
Our goal is to make Cloudflare the simplest, most secure, and most programmable cloud for agents.
Integrating with Claude Managed Agents is another step in this direction. You can run your agent loop on the Claude Platform, while using Cloudflare to execute code, secure connections, and run custom tool calls.
To get going in just minutes, we’ve created a default deployment template that gives you the following:
Enhanced security - Run all agent traffic through customizable proxies. This allows you to securely inject credentials, prevent data exfiltration, and better observe how your agents interact with the outside world.
Sandbox control and observability - Get Continue reading
If he had been a programmer, Cardinal Richelieu would have said “Give me six lines written by the hand of the most expert C programmer in the world, and I will find enough in them to trigger undefined behavior”.
Nobody can write correct C, or C++. And I say that as someone who’s written C and C++ on an almost daily basis for about 30 years. I listen to C++ podcasts. I watch C++ conference talks. I enjoy reading and writing C++.
C++ has served us well, but it’s 2026, and the environment of 1985 (C++) or 1972 (C) is not the environment of today.
I’m definitely not the first to say this. I remember reading a post by someone prominent about a decade ago saying that a good case can be made that use of C++ is a SOX violation. And while I was not onboard with the rest of their rant (nor their confusion about “its” vs “it’s”), I never disagreed about that point.
With time I found it to be more and more true. WAY more things are undefined behavior (UB) than you’d expect.
Everyone knows that double-free, use after free, accessing outside the bounds of an Continue reading
For the last few months, we've been testing a range of security-focused LLMs on our own infrastructure. These LLMs help identify potential vulnerabilities in our own systems, so we can fix them – and they also show us what attackers are going to be able to do with the latest models.
None of these LLMs has captured more attention than Mythos Preview, from Anthropic. A few weeks ago, we were invited to use Mythos Preview as part of Project Glasswing. We soon pointed it at more than fifty of our own repositories – to see what it would find, and to see how it works.
This post shares what we observed, what the models did well and what they didn't, and how the architecture and process around them needs to change, so they can be used at scale.
Mythos Preview is a real step forward, and it's worth saying that plainly before getting into anything else. We've been running models against our code for a while now, and the jump from what was possible with previous general-purpose frontier models to what Mythos Preview does today is not just a refinement of what came before.
It's Continue reading
netlab release 26.05 is out. I’ll write about its highlights tomorrow; today, I want to focus on one of its breaking changes: netlab no longer works with Python 3.8 (which reached end-of-life in October 2024), so you can no longer install it on a vanilla Ubuntu 20.04 (which reached end of standard support a year ago).
We wanted to get rid of old Python versions for ages, but never did because Ubuntu 20.04 shipped with Python 3.8, and many netlab early adopters installed it on Ubuntu 20.04 (and the last thing a networking engineer wants is wasting time with upgrades, right?).

I run a lot of applications and services in my homelab, and they usually look something like http://10.10.10.10:8000, http://10.10.10.11:8006, and so on. It works, but it comes with a few annoyances. Browsers constantly complain you about insecure connections, and remembering which IP and port maps to which service gets old fast.
The ideal setup is something like https://netbox-lab.yourdomain.com - a proper domain name with a valid SSL certificate and no port numbers to remember. In this post, I'll show you how to get there using Caddy, Cloudflare, and Let's Encrypt with very minimal effort.
To make this work, we need the following.
I already have a domain that I use in my homelab, so I name my services like app.yourdomain.com. I purchased this domain through Cloudflare and manage it there.
To generate an API Continue reading

If you have used Nornir before, you already know that the most common way to define your inventory is through YAML files. You list your hosts, groups, and defaults in separate files, and Nornir reads them at runtime. This works fine for small labs or quick scripts, but as your network grows, maintaining those files by hand becomes a problem. Every time you add a device, change an IP, or update a site, you have to remember to update your inventory files as well. It is easy to get out of sync.
This is where a source of truth tool like NetBox can help. NetBox is an open source network source of truth. It is a place to document your devices, IP addresses, sites, roles and pretty much anything about your network. Instead of maintaining a separate YAML inventory alongside NetBox, you can pull your inventory directly from NetBox at runtime. That way, Nornir always works with up to date data, and you only have to manage one source of truth.
In this post, we will cover how to use NetBox as a dynamic inventory source for Nornir using the nornir_netbox plugin. If you are new to Nornir, we have Continue reading
We don’t often hear the stories of those who move from some other IT career field into network engineering. Ayush Mishra, a student at University of Colorado Boulder, joins Tom and Russ to discuss why he moved from security to network engineering.
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