# John Nielsen

John Nielsen writes about practical cybersecurity and digital resilience for businesses. Nielsen's LinkedIn posts explain risks such as email spoofing, weak physical network access controls, and dependence on payment or software providers, then offer concrete steps companies can take.

- Profile: https://b2binfluencer.marketing/creators/john-nielsen/
- LinkedIn: https://www.linkedin.com/in/johnnielsendk
- LinkedIn followers: 26,159
- Based on 15 dated posts, latest 2026-10-09

## Summary

Practical Danish-language cybersecurity and digital resilience posts for business audiences.

- Best for: Editorially led Danish-language B2B campaign on cybersecurity and resilience.
- Not for: Consumer lifestyle campaigns, short-form video, discount codes or mass consumer app downloads.
- Check first: Confirm audience fit and commercial terms, since no media kit or rates are published.

### Takeaways

- A visitor can reach an internal network through an unguarded meeting-room port.
- A forged email can misuse a company's domain; SPF, DKIM and DMARC have limits.
- A payment-provider outage can stop sales; map provider chain and plan 48 hours.

## Main ideas

- **A familiar sender name is only as safe as the domain owner's instruction**: Nielsen argues that email spoofing is often treated as an inbox-filter problem, but the decisive control sits with the organisation that owns the domain. SPF and DKIM show whether a message came from an approved system; DMARC tells the recipient what to do when that check fails. Without a quarantine or reject instruction, the recipient's filter alone decides. They measure this by sector and urge organisations to inventory every system that sends mail, then set a dated plan. They also warn that DMARC is no guarantee: a hosting provider that switches existing domains to reject without checking customers' senders could block legitimate mail.
- **Security testing should cover the front door, not only the network**: Nielsen distinguishes three services buyers often blur. A penetration test attacks selected technical systems. Red teaming imitates a real attacker across technology, people and buildings. Cyber security mystery shopping tests how far a visitor gets as a customer, supplier or guest. They argue that a firewall or technical test cannot stop an attacker who has already walked into the meeting room. Practical checks include counting active network ports, asking what happens when an unknown device connects and requiring tests that cover doors, people and response time.
- **Payment outages are a continuity decision, not just a technical failure**: Nielsen argues that a payment outage should be judged by what happens at the till, not only by its cause. A technical fault and a ransomware attack can both stop card payments. Payments depend on a terminal supplier, gateway, acquirer, processor and subcontractors; if one critical link fails, money stops even when the company's own systems are working. They urge businesses to confirm offline payment capability, map the chain and decide in advance how to operate for 48 hours without cards. Some shops had offline capability during the July outage but did not use it.
- **Foreign sanctions make supplier dependence a sovereignty question**: Nielsen argues that sanctions and foreign law travel through commercial relationships, including banks, insurers and software suppliers. A company may not be the direct target yet still lose access to a service when a supplier decides the legal risk is too high. The management task is to list critical providers, note which country's law governs each and ask how they handle sanctions. Test alternatives against the same exposure. The ICC case shows the value of a plan B: the court had already moved office software and arranged replacements before sanctions hit the organisation.
- **Automated deletion rules need testing like any other control**: Nielsen treats automated deletion as a control that can fail quietly in either direction: removing records too early or keeping them too long. Rules must use the right deadline, count from the right date and handle exceptions. They recommend listing automated deletion rules with their legal basis and last check, testing the most important rule with data that should be kept, deleted or exempted, and clarifying how deletions are logged and corrected. A deletion log is not a copy of the deleted data.

## Work to read

- [Hackeren i hættetrøjen bliver stoppet i jeres reception](https://www.linkedin.com/posts/johnnielsendk_hackeren-i-h%C3%A6ttetr%C3%B8jen-bliver-stoppet-i-jeres-activity-7513823534876446720-qB5V)
- [Under nedbruddet i juli kunne nogle butikker have taget imod kortbetalinger offline](https://www.linkedin.com/posts/johnnielsendk_under-nedbruddet-i-juli-kunne-nogle-butikker-activity-7514254199061127169-8Va0)
- [Et falsk kogepåbud i indbakken. Vandværkets navn som afsender.](https://www.linkedin.com/posts/johnnielsendk_et-falsk-kogep%C3%A5bud-i-indbakken-vandv%C3%A6rkets-activity-7504951550411403264-p0x_)
- [En afgørelse manglede i Kriminalregisteret. Den skulle have været gemt.](https://www.linkedin.com/posts/johnnielsendk_en-afg%C3%B8relse-manglede-i-kriminalregisteret-activity-7503388021547835392-FHMj)

## Brand relationships

- **DMARC-tjek.dk** (owned_business)
- **DMARC Barometer** (owned_business)

## Partnerships

John Nielsen's posts contain no published partnership or sponsorship formats. The nine posts are cybersecurity commentary and advisory writing in Nielsen's own voice; none is labelled as sponsored, and no media kit, rate card, deliverable list, or sponsor policy appears in the posts here. The one recurring commercial element is a subscription link at the end of every post, inviting readers to a newsletter Nielsen describes as reaching "4,400+" subscribers with patterns from "500+ cases" and recommendations on digital sovereignty and cybersecurity every 14 days. That is Nielsen's own audience channel, not a documented brand offer, and the subscription terms and audience figures are Nielsen's own stated claims rather than figures verified elsewhere. Because the posts set out no formats, pricing, approval steps, or usage rights, a buyer cannot plan deliverables or budget from the information published here; any collaboration would have to be scoped in direct negotiation, and those terms remain unverified. The post about network access control shows Nielsen performs penetration tests, red teaming exercises, and security mystery shopping for clients, which indicates the kind of professional engagement Nielsen does, but it is not presented as a creator partnership offering and carries no commercial specifications. A reasonable planning assumption is that a brand approaching Nielsen is buying access to the professional audience through a practitioner who writes from client work, and that the practical constraints — what Nielsen will endorse, how work is labelled, and what Nielsen charges — are unknown until discussed with Nielsen. The posts here do not document sponsorship; that does not mean Nielsen never accepts sponsorship.

## Alternatives

- Christian Lunøe Gøtzsche: A better fit than John Nielsen only if the buyer reframes resilience around AI governance: how commercial teams use AI agents, where data sits, and how EU AI Act and GDPR guardrails are built into workflows. The posts show a commercial leader testing an autonomous agent workflow for a B2B company and arguing that governance should provide strategic guardrails, not act as a bureaucratic brake. For a mid-sized Danish company whose immediate risk is ungoverned AI use in sales or marketing, this is the more direct content fit.
- Micky Weis: A better fit when the buyer's cyber resilience question is really about operational readiness in e-commerce: email and customer flows, Q4 preparation, content production and using AI on first-party data. The posts offer concrete checklists for flows, branding, onsite merchandising and data analysis. For a Danish e-commerce business whose continuity risk lies in customer communication and trading readiness, Micky Weis offers more directly usable campaign material than Nielsen's security-testing posts.
- Stefan Kløvning: A better fit when the buyer's resilience decision concerns system integration and third-party dependency: how CRM and finance systems connect, and what happens when a shared platform fails. The Cloudflare post identifies single points of failure and recommends mapping risks, backups, crisis protocols and training; the integration post explains when no-code, low-code or full-code fits. For a mid-sized Danish company worried about supplier concentration and continuity, this is closer to the operational resilience question than John Nielsen's testing-focused material.

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AI-assisted summary of public posts. Audience demographics are not available. Engagement appears only where we checked recent posts. Method: https://b2binfluencer.marketing/methodology/