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Web Config Ops — Subnets, Permissions, HTTP Status & CSS Units

Hub for Tools.Town server and web config math: IPv4 CIDR subnetting, chmod permission modes, HTTP status code lookup, and px ↔ rem conversion — free, in-browser.

16 August 2026 4 min read By Tools.Town Team Fact Checked

Key Takeaways

  • What is Web Config Ops: A Tools.Town cluster for the config math behind running websites and servers — IPv4 subnetting, Unix file permissions, HTTP response codes, and CSS unit conversion
  • Does the subnet calculator support IPv6: Not yet — it covers IPv4 CIDR /0 through /32 with network, broadcast, mask, wildcard, and usable host range
  • Is 777 ever the right chmod mode: Almost never on shared hosting

Pick the tool by the config job

Server and site config keeps asking the same four questions. Web Config Ops is the Tools.Town cluster for answering them without a CLI or a cheat-sheet tab.

QuestionTool
”What’s the network and host range for this /27?”Subnet Calculator
”What octal mode is rwxr-xr-x?”Chmod Calculator
”What does 422 mean, and should I return 409 instead?”HTTP Status Code Lookup
”How many rem is 18px at root 16?“px ↔ rem Converter

Subnetting: CIDR without the bit math

Paste an IPv4 address and prefix into the Subnet Calculator to get mask, network, broadcast, wildcard, and usable host range — ready for firewall rules and VPC blocks. Planning capacity? Start with Size a Subnet for a Small Office or VPC. Validate inputs first with the IP Address Validator.

Permissions: build modes visually

The Chmod Calculator turns rwx checkboxes into octal and symbolic modes, and decodes octal back into flags. The eternal question — 755 vs 644, which and when — has a short answer and a guide. Broken uploads after a migration? Follow Fix WordPress File Permissions. Looking up plugins, PHP, or salts? That is WordPress.org Ops, not chmod.

HTTP: return the right status

Mid-incident, the difference between 409, 422, and 503 matters. The HTTP Status Code Lookup covers 100–599 with a searchable table and guidance per code. Designing an API? Work through Pick the Right HTTP Status for an API, and inspect live responses with the HTTP Header Inspector.

CSS units: px ↔ rem at any root

Design specs quote px; accessible CSS prefers rem. The px ↔ rem Converter converts both directions at any root font size. Building a whole scale, not one value? Use the Type Scale Generator.


  • Auth and tokens (JWT, hashes, passwords) live in the Dev Auth cluster — start at the JWT Decoder.
  • Protecting a folder after fixing permissions? .htpasswd Generator.

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Frequently Asked Questions

What is Web Config Ops?
A Tools.Town cluster for the config math behind running websites and servers — IPv4 subnetting, Unix file permissions, HTTP response codes, and CSS unit conversion. All tools run in your browser.
Does the subnet calculator support IPv6?
Not yet — it covers IPv4 CIDR /0 through /32 with network, broadcast, mask, wildcard, and usable host range.
Is 777 ever the right chmod mode?
Almost never on shared hosting. Use 755 for directories and 644 for files as the safe default; see the 755 vs 644 guide for when to deviate.

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