skip to content

sysop@hub:~/tools$

tools

Everything runs in your browser. Nothing you enter is sent anywhere.

practise 6

Learn by doing, on pretend systems that you cannot break.

linux-playgroundA pretend Linux server with eighteen missions: broken web server, full disk, web shell, and how they got in. Real commands, in the browser.powershell-playgroundA pretend Windows server with twelve missions on the object pipeline: services, files, logons, AD users.sql-playgroundSQL in an afternoon: 22 lessons with a practice database, checked as you go.packet-journeyOne web request from PC to server, station by station. Break it, then guess ten faults from their symptoms.incident-simFour incidents where you make the calls: now with ransomware on a Monday morning, in thirteen decisions.phish-or-legitTen mails. Which ones are phishing?

fix it 19

Something is broken or slow. Walk through it, or look the error up.

switch-port-finderWhich port is this device on? From IP address to MAC address to the switch port, in six steps.disk-fullNo space left on device: find it, free it safely, and make logrotate do its job.call-qualityChoppy, delayed, echo, one-way: seven steps from the headset to the provider.dhcp-not-workingNo address or the wrong one: nine steps from the client to the switch port.dns-not-resolvingIt is always DNS: eight steps from the client's resolver to the server's forwarders.git-fix-itWrong commit, wrong branch, rejected push, lost work: the command that gets you out.group-policy-not-applyingEight steps from gpresult to SYSVOL for a policy that does not arrive.docker-container-troubleshootingThe container does not start, restarts or cannot be reached: eight steps with commands.database-slowEight steps to the cause, with the queries for PostgreSQL, MySQL and SQL Server.linux-server-slowEight steps from load average to the cause: commands, how to read them, what to do.windows-pc-slowEight steps from Task Manager to the cause of a slow Windows PC.stop-code-lookupThe blue screen code in plain words: what it means, usual causes, what to do first.diagnoseTroubleshooting wizard for sign-in, email, network, printers, monitors, docks and PCs that do not start.helpdesk-top-ticketsThe 20 requests every helpdesk gets: ask first, usual fix, when to escalate.mailflow-debuggerPaste a bounce or SMTP error. Get the cause, who has to fix it, the commands and a reply for the user.aadsts-lookupEnter an Entra sign-in error code and get its meaning and the usual fix.incident-runbookAnswer a few questions, get a tailored step-by-step incident response runbook.dns-lookupLive DNS record lookup (A/AAAA/MX/TXT/NS/CNAME/SOA/CAA) via DNS-over-HTTPS, resolved in your browser.status-centerOfficial status page links plus a live reachability check for M365/Azure endpoints.

read a file 10

Drop a log, an export or a certificate and get it in plain words.

mail-header-readerThe route of an email as a timeline, the wait at every hop, SPF, DKIM and DMARC explained.dcdiag-readerPaste dcdiag and repadmin output. Get the failed tests and replication errors explained, most urgent first.dmarc-report-readerDrop the XML reports. See who sends mail in your name, what fails, and whether you can enforce the policy.config-reviewerPaste sshd_config, nginx or a Compose file. Get the risky lines explained, and what to write instead.log-readerDrop an access log, auth.log or syslog. Who tried to get in, what failed, what repeats.smart-readerPaste smartctl output. Is the disk failing, which numbers matter, disk or cable?certificate-decoderPaste a certificate or a chain. See names, expiry, chain order and why a client refuses it.firewall-rule-reviewerDrop NSG rules, an iptables dump or a CSV. See what is open to the internet and which rules never apply.phish-analyzer“Is this mail real?” Drop the .eml and get a verdict with reasons. Nothing is uploaded or opened.domain-checkCan your domain be spoofed? Graded SPF, DMARC and DKIM audit from live DNS, with the records to publish.

build and calculate 11

Get the command, do the maths, compare the options.

regex-testerTest a pattern, get every part explained, the usual traps, and the same pattern for grep, sed, PowerShell and Python.systemd-unit-builderA service and timer unit from a few questions, every line explained.cron-builderA cron expression in plain words, its next runs and traps, and the same as a systemd timer and a Windows task.connection-string-builderPostgreSQL, MySQL, SQL Server, SQLite, MongoDB, Redis: every common form from one set of fields.command-builderrobocopy, rsync, tar and find: tick options, get the line with every switch explained.bash-powershell-side-by-side105 everyday tasks in Bash and in PowerShell. Search by task or by the command you know.raid-calculatorCapacity, how many disks may fail, and the chance a rebuild hits a read error. All levels side by side.transfer-time-calculatorHow long does the copy take? Amount and speed in, time out. Mbit/s and MB/s told apart.subnet-calculatorCIDR in, network/broadcast/host range out, with a visual address map.cvss-calculatorBuild or decode a CVSS 3.1 vector: score, severity and plain-language meaning of each metric.password-strengthEntropy and crack-time estimates for any password, computed locally.

plan 16

For the work you can schedule: networks, backups, dates.

it-documentationThe IT handbook with emergency page, networks, servers, admin accounts, backups and contacts. Finds the gaps, prints clean.new user-howto-cardsSix one-page instructions for colleagues, to print: MFA, VPN, printer, password, phishing, meetings.new licence-trackerSubscriptions with renewal dates and notice periods: what it costs, what to decide this month.new subnet-vlan-posterPrefixes, masks, ranges, ports and your own VLANs on two pages to print.phishing-drill-kitPlan, rules, three sample mails and fair counting for a phishing exercise.asset-inventoryDevices, serial numbers, users and warranty dates, with CSV import and export.network-diagram-builderDraw the network, label the links, get it checked, save as SVG or PNG.security-postersTen plain awareness posters for the office wall, with your contact line, ready to print.wifi-channel-plannerWhich channels you can use and which access point gets which, with a drawing of the band.incident-plan-builderThe one page for the wall: first 15 minutes, who to call, where the backups are.uptime-sla-calculatorWhat 99.9% means in minutes, and what a chain of parts does to it.small-office-blueprintPeople and way of working in, network layout, sized shopping list and checklist out.ip-plan-builderAddress range and segments in, VLAN and subnet plan with switch and DHCP configuration out.backup-plannerRetention, storage needed, backup and upload times, and a 3-2-1-1-0 check of your plan.attack-mapInteractive kill chain for M365 and AD. Toggle your controls, see the open routes.product-lifecycleLive end-of-support countdown for Windows Server, Windows, Exchange, SQL Server, Office and SharePoint.patch-tuesdayNext 8 Patch Tuesdays with a live countdown, plus a common rollout-ring cadence.

hardware 11

What is this plug, what fits where, and why does it not switch on.

storage-upgrade-plannerWhich SSD fits, M.2 keys and lengths with drawings, and the steps to clone.pc-build-checkerDoes the parts list fit? Socket, memory, sizes, plugs and power, with a scale drawing.bios-settings-explainedWhat the firmware settings do, what to set, and what breaks when you change them.monitor-no-pictureThe wizard for a black screen, flicker or a second monitor that is not found.dock-not-workingThe wizard for USB-C and Thunderbolt docks: no picture, no charging, dropouts.rack-plannerPlace devices by rack unit and get a drawing, with weight, power and heat.beep-code-lookupWhat the beeps and blinking lights of a PC that does not start mean, by vendor.ups-runtime-calculatorHow long the UPS holds, with new and aged batteries, and when to start the shutdown.poe-budget-calculatorCan the switch power all phones, access points and cameras?connector-identifier42 plugs and slots drawn face-on: how to tell them apart, and what goes wrong with each.pc-does-not-startThe wizard for a PC or notebook that stays dark: seven questions to the part that stops it.

microsoft 365 and entra 9

Analyzers and builders for the Microsoft cloud.

signin-analyzerDrop an Entra sign-in export, get a threat-hunting report with next steps and KQL. Runs in your browser.ca-analyzerPaste your Conditional Access export: gaps, exclusions and each policy in plain language.ca-policy-builderPick from 16 proven policies, get the script that creates them in report-only, with a lockout check.app-auditWhich apps could take over the tenant, read all mail, or were approved by a tricked user? Drop the export.intune-analyzerDrop the Intune device export. See how healthy the fleet is and which devices are behind each problem.license-optimizerDrop the user and licence export. See which licences pay for nothing, in money per month.license-comparisonM365 and Entra ID tiers side by side: what's actually included in each plan.script-generatorFill a form, get a ready-to-run offboarding, bulk-user, mailbox-permission or Conditional Access script.cockpitYour own dashboard: domain grade, open attack routes, CA coverage and end-of-support watchlist, stored only on your device.

quick tools 21

Small utilities, all on this page. Jump to one:

cidr-calculator

Enter an IPv4 address with prefix length and get network, broadcast, mask and host range. Want a visual map and a prefix slider? Try the full subnet calculator.

jwt-decoder

Paste a JSON Web Token to read its header and claims. Decoding happens in your browser; the signature is not verified.

hash-generator

Type or paste text to get its SHA-1, SHA-256, SHA-384 and SHA-512 hashes, computed locally in your browser.

password-generator

Random passwords from your browser's secure random generator. Nothing is stored or sent. Want to test an existing password instead? Try the password strength & crack-time estimator.

length 20 a-zA-Z0-9symbols

time-converter

Convert Unix seconds, Unix milliseconds, Windows FILETIME (Active Directory values such as lastLogon and pwdLastSet) or a date string.

base64-tool

Encode text as Base64, build a PowerShell -EncodedCommand string, or decode Base64 as UTF-8 and UTF-16LE to inspect encoded commands.

guid-generator

Random version 4 GUIDs, generated in your browser.

count uppercasebracesno hyphens

email-header-analyzer

Paste the full raw headers of an email to see the sender fields, SPF, DKIM and DMARC results and the delivery path. Processed locally.

port-reference

Common TCP and UDP ports for admins. Search by number, service or keyword.

regex-tester

Test a JavaScript regular expression against text and see matches and capture groups. Flags such as i, m and s are supported; g is always on.

json-formatter

Validate JSON and get a formatted and a minified version.

url-encoder

Percent-encode or decode text for use in URLs.

cron-explainer

Enter a standard five-field cron expression, or a shortcut such as @daily, and see what each field means.

uac-decoder

Decode an Active Directory userAccountControl value, in decimal or hex, into its flags.

spf-explainer

Paste an SPF record (the TXT value) and get each part explained, including a count of DNS lookups.

dmarc-explainer

Paste a DMARC record (the TXT value of _dmarc) and see the policy, alignment and reporting settings.

markdown-previewer

Type or paste Markdown and see it rendered live. Supports headings, bold, italics, links, lists, code and tables.

text-diff

Compare two blocks of text line by line to see what changed, for example two config file versions.

case-converter

Convert text between camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and Title Case.

ipv6-tool

Expand a shortened IPv6 address to its full form, or compress a full address to its shortest form.