Merlin
LAN port scan forbidder

LAN port scan forbidder

Forbid non-LAN webs to access LAN or localhost. An anti-scan protection

What is LAN port scan forbidder?
LAN port scan forbidder is a Firefox add-on that forbids untrusted websites from scanning localhost or LAN. It provides protection against unauthorized port scans and helps prevent tracking fingerprinting.
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Merlin
Stats
By: GarryW
Users: 50 ▼ -1
Rating: 1.00 (1)
Version: 0.6.2 (Last updated: 2024-03-22)
Creation date: 2021-06-05
Weekly download count: 2
Firefox on Android: Yes
Risk impact: High risk impact
Risk likelihood: Moderate risk likelihood
Manifest version: 2
Permissions:
  • webRequest
  • webRequestBlocking
  • *://*/*
  • ws://*/*
  • wss://*/*
  • ftp://*/*
  • contextMenus
  • storage
  • tabs
Size: 42.76K
URLs: Website
Stats date:

Chrome-Stats Rank

# 13111 ▼ 169
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Other platforms

Not available on Chrome
Not available on Edge
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Merlin
Summary
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Forbid untrusted web to scan localhost or LAN. Browser addon.

What

Webs can try to fetch 127.0.0.1:xxxx or 192.168.Y.Z:xxxx to scan your open ports in LAN.

Although browsers have cross-domain protections, webs can't read response contents, but can still see the connection succeeds or fails.

There're already reports that some websites using that as tracking fingerprint.

A web for testing: http://samy.pl/webscan/
So

Forbid any website behaviors trying to connect to your LAN or localhost, if user is visiting the website via their domains or public IP addresses. (Read the source code background.js to see the logic)

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User reviews
Out of memory crash: https://github.com/garywill/LAN-port-scan-forbidder/issues/4.
by Peter Kehl, 2024-02-24
View all user reviews
Safety
Risk impact

LAN port scan forbidder is risky to use as it requires a number of sensitive permissions that can potentially harm your browser and steal your data. Exercise caution when installing this add-on. Review carefully before installing. We recommend that you only install LAN port scan forbidder if you trust the publisher.

Risk likelihood

LAN port scan forbidder is probably trust-worthy. Prefer other publishers if available. Exercise caution when installing this add-on.

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Screenshots
LAN port scan forbidder