Outbound Port Monitor

Outbound Port Monitor watches Firefox's own outgoing traffic and logs the destination port of every completed request as it happens — straight from the browser's networking layer, not a packet capture or a separate monitoring tool.

See at a glance which ports a page, script, or embedded service is reaching out to while it loads: the current port sits in a bold, glowing box at the top of the sidebar, and every request before it scrolls down a running log with its host, request type, timestamp, and a plain-English service name drawn from a comprehensive, IANA-based reference table.

Built for anyone curious what a page's network activity actually looks like underneath the rendered screen — hobbyists, students learning how ports and services map together, and privacy-minded users who like a lightweight, always-visible companion while they browse.

🏛 About Outbound Port Monitor: • A single page load can quietly open connections to dozens of hosts and ports — the main site, embedded scripts, CDNs, trackers, WebSocket feeds. • Outbound Port Monitor doesn't interpret, judge, or block any of it: it reports the destination port and host of each completed request exactly as observed, nothing added or guessed.

📐 Desktop Sidebar Design: 🟦 Current Port Box: A bold, glowing highlight always shows the single most recent destination port and host, colored to its range. 📜 Scrolling Log: Every captured request below it, newest on top, oldest at the bottom — Time, Port, Host, Type, and Description in each row. 🎨 Three-Color Classification: Red for well-known ports (1–1024), green for registered ports (1025–49151), yellow for dynamic/ephemeral ports (49152–65535). 📤 Export List: One click saves the full log to a timestamped .txt file. 🗑 Clear List: One click wipes the log and resets the current-port box.

⚙ How It Works — Observation Only, Nothing Sent Anywhere: • Outbound Port Monitor listens to Firefox's webRequest API for completed requests only; it never reads request or response bodies, headers, or cookies. • The destination port comes straight from the completed request's own URL, falling back to the scheme's standard port (80, 443, or 21) when none is explicit. • Repeat requests to the same port and host within a 2-second window are shown once, so a single page load doesn't flood the log with near-duplicates. • The log holds up to 2000 entries, rolling off the oldest once full. • Every row is built with safe, text-only DOM methods — nothing is ever inserted as HTML.

📚 Port Description Coverage: The reference table comes from the IANA-based nmap-services registry, applied in three deliberate tiers: • Well-known ports (1–1024): every port with a registered name is included — 729 of the 1024 possible ports. The rest have no IANA assignment at all and are shown as "Unassigned." • Registered ports (1025–49151): the 600 most commonly observed ports are included, ranked by real-world open-frequency data, out of thousands of formal assignments in this range. Anything outside this curated set is shown as "Unregistered" — not necessarily unassigned, just uncommon. • Dynamic/ephemeral ports (49152–65535): assigned on the fly by the operating system rather than to a fixed service, so they are never catalogued individually — the extension recognizes the whole range by number and labels it "Ephemeral / Dynamic (client-assigned)."

📊 What You See: 🟦 Current Port Box: Port and host of the most recent request, bold and color-coded. 📋 Log Table: Time, Port, Host, Type, and Description for every retained entry. 🎨 Row Coloring: The Port column colored by range for instant visual triage. ✨ Bright, High-Contrast Theme: Neon accents on a dark background, built for quick scanning.

🖥 Features: 🔎 Real-Time Capture — Every completed outgoing request, logged the moment it finishes. 🎨 Port-Range Coloring — Red / green / yellow across well-known, registered, and dynamic ports. 🧾 Comprehensive Descriptions — 1,329 curated port names, plus rule-based labels for every unnamed or ephemeral port. 📤 Timestamped Export — One click writes the full log to a local .txt file. 🗑 One-Click Clear — Resets the log and the current-port display instantly. 🪶 Zero Overhead — Six small files; nothing runs while the sidebar is closed. 🔒 Client-Side Processing — All capture, coloring, and formatting happen in your browser.

🎯 Perfect for: • Anyone curious what ports a page is quietly reaching out to while it loads. • Users who want a lightweight, always-visible network companion during normal browsing. • Students and hobbyists learning how port ranges and common services map together.

🔒 Security-First Architecture: ✅ No Data Collection — Explicitly declared in manifest.json. ✅ No Telemetry — No analytics, no tracking, no third-party requests of any kind. ✅ No eval() or innerHTML — Every row and label is built with safe, text-only DOM methods. ✅ Validated Input — Every captured port is checked as an integer in the 1–65535 range before it is stored; malformed URLs are silently skipped. ✅ Minimal, Purpose-Bound Permissions — Every permission requested maps directly to a visible feature (see Technical Details). ✅ Flat, Auditable Codebase — Six files total: manifest, background script, port-name data, sidebar HTML, sidebar script, and one stylesheet.

🛠 Technical Details: • Compatibility: Firefox 140.0+ Desktop only. • Runtime Execution RAM Footprint: ~37 KB (core scripts: manifest.json + sidebar.html + style.css + sidebar.js + background.js + ports.js). • Total Extension Download/Install Size: ~86 KB (including README.md). • Entry point: sidebar_action panel (sidebar.html). • Network requests: None initiated by the extension — it only observes requests the browser was already making. • Storage: None. The log lives in memory only and clears on restart or manual clear. • Permissions requested: webRequest (to observe completed requests), the <all_urls> host permission (required for webRequest to see requests to any destination), and downloads (for the Export List button). • Data Collection: None (explicitly declared).

⚠ Limitations: 🖥 Desktop Only — Firefox sidebars are not available on Android. 🌐 HTTP(S)/WS(S)/FTP Only — Captures the request types Firefox's webRequest API reports, covering the large majority of ordinary browsing traffic but not every possible network path (for example, some WebRTC media streams). 📶 Duplicate Suppression — Rapid repeat requests to the same port and host within 2 seconds are shown once, by design, to keep the log readable during page loads. 📚 Curated, Tiered Descriptions — See Port Description Coverage above for exactly which ports are named and why the rest are not. 🕵 Not a Security Scanner — Ports and hosts are reported as observed; the extension does not evaluate, flag, or block anything. That judgment is left to the user.

⚠ Legal Disclaimer: Outbound Port Monitor is an independent browser extension, not affiliated with, endorsed by, or responsible for the content of any website or service it observes traffic to.