ronutz

由从业者打造，以隐私为先

把您的数据留在您设备上的网络与安全工具集。

子网计算、DNS 与电子邮件诊断、证书检查等等，全部在您的浏览器中本地完成。日常工具无需上传、无需日志、无需账户。

Around the tools: sourced articles on how the technology works, a record of the companies that built this industry, the practice of doing the work, and the roles that do it.

现已上线

152 工具553 文章

由一位自 1996 年起就从事这项工作的人打造。

在企业网络与安全领域深耕三十年，由一位活跃的讲师亲自呈现，而非一页市场文案。横跨平台的认证，意味着这里的对比是诚实的，而不是为了促成交易。

The chapters lived from inside

In every one of these, employer or vendor, the work was the same shape: facing the end customer, in pre-sales and in post-sales technical support, and very often acting as the technical proxy and enablement facilitator for the partners who had to carry the product themselves. The job was to leave the customer with something that worked better than it did before — an innovation, a solution, an improvement they could keep running after I left. The full telling lives at the career record.

The roles I have held

Eight positions across the path a product takes, each linking to what that job answers for, who it serves and how it is measured. The years are the ones on each entry, including the spans that are not continuous.

平台，持续教授并保持最新。

What is here

Vendor hubs →

One door per platform: the tools, articles and certification material for that vendor, gathered in one place.

8 vendor hubs

Certification guides →

What each exam tests and what to study for it. Free, and useful whether or not you ever book a course.

105 guides

Study guides →

Curated reading paths through the Learn library: an ordered route through a subject, built for understanding it rather than for passing an exam.

105 guides

Glossary →

Every term and acronym used across this site, defined once and cross-referenced. The thing to open mid-article.

1242 entries

The Practice →

How the work is actually done rather than how the technology works. Triage, escalation, evidence, handover.

64 published

The Roles →

The positions this industry is made of, grouped by the path a product takes from the company that builds it to the person who depends on it.

39 positions

Tools →

Deterministic calculators and explainers for networks, security and identity. They compute in your browser and send nothing anywhere.

152 live

Learn →

Technical articles on the protocols and products behind the tools, written to be read rather than skimmed.

553 articles

Industry →

Company histories from the beginning of networking to now, including the ones that failed and the ones nobody remembers.

289 companies4 of them turn 50 this year

About →

Who is writing all of this, what I have done, and why any of it should be trusted.

The career record →

Fifteen chapters from 1996 onward, each told from inside the company it happened in.

15 chapters

Advisory →

Independent judgement on decisions that have not been made yet. Scoped work, written answer, no on-call.

By engagement

Training I teach →

Authorized instructor-led courses across four platforms, delivered through Red Education.

28 courses across 4 vendors

Red Education →

The global authorized training centre my courses are delivered through, and the story of how it got there.

为什么在安全工作中本地运行很重要。

当您把配置、抓包或证书粘贴到工具里时，这些数据往往包含机密。在这里，日常工具完全在您的浏览器中运行。您输入的内容从不离开您的设备，因此没有什么可被记录、泄露，或在法庭命令下被交出。

现在就试用工具。

下方的 CIDR 计算器在本地运行。输入网络和前缀，即可看到地址范围、主机数量和掩码。没有任何内容被发送到任何地方。

打开完整工具箱 →

CIDR 计算器

分析单个 IPv4 CIDR 块：网络、广播、掩码和主机范围。

本地运行，不向任何服务器发送任何内容。