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IPv6 Zone ID Helper

Validate IPv6 addresses with zone identifiers and get suggestions (useful for link-local addresses).

About This Tool

The IPv6 Zone ID Validator analyzes IPv6 addresses with zone identifiers (also called scope identifiers), which are essential for disambiguating link-local and site-local addresses. The zone identifier (e.g., %eth0, %en0, %1) specifies which interface or zone an address belongs to, as link-local addresses (fe80::/10) can be identical across different network interfaces. This tool validates the zone ID syntax, identifies address types requiring zones, suggests possible zone identifiers, and helps troubleshoot connectivity issues with IPv6 addresses that need explicit scope specification.

How to Use

  1. Enter IPv6 addresses in the textarea, one per line
  2. Addresses can include zone identifiers (e.g., fe80::1%eth0)
  3. Or enter addresses without zones for analysis (e.g., fe80::1)
  4. Click "Analyze" to validate and process all addresses
  5. View summary showing valid inputs and addresses requiring zones
  6. For each address, see its type, zone presence, and validity
  7. Check suggested zone IDs for addresses that need them
  8. View both "with zone" and "without zone" representations

Features

  • Validates IPv6 addresses with zone identifiers
  • Detects address types (link-local, site-local, global, etc.)
  • Identifies which addresses require zone IDs
  • Suggests possible zone identifiers (eth0, en0, wlan0, etc.)
  • Shows both with-zone and without-zone representations
  • Batch processing of multiple addresses
  • Validates zone ID syntax
  • Summary statistics for quick overview
  • RFC 4007 compliant validation

Common Use Cases

  • Debugging link-local IPv6 connectivity issues
  • Validating configuration files with zone identifiers
  • Understanding which IPv6 addresses need zone IDs
  • Troubleshooting "Invalid argument" errors with IPv6
  • Learning when and how to use zone identifiers
  • Analyzing IPv6 addresses from packet captures
  • Configuring applications that use link-local addresses
  • Network automation scripts handling link-local addresses
  • Educational purposes: teaching IPv6 scope concepts
  • Verifying correct zone ID syntax in documentation

Technical Details

Zone identifiers (RFC 4007) disambiguate IPv6 addresses with non-global scope. Since link-local addresses can be identical on different interfaces, the zone ID specifies which interface to use.

Zone ID Syntax:

  • Format: address%zone_id
  • Example: fe80::1%eth0, fe80::1%2, 2001:db8::1%site1
  • Zone ID can be interface name, numeric index, or scope name
  • Percent sign (%) separates address from zone identifier

When Zone IDs Are Required:

  • Link-local (fe80::/10): Always require zone for communication
  • Site-local (fec0::/10, deprecated): Required for multi-site hosts
  • Multicast link-local (ff02::/16): May require zone
  • Global unicast: Never require zone (globally unique)

Common Zone ID Forms:

  • Linux: eth0, eth1, wlan0, docker0, etc.
  • macOS: en0, en1, lo0, etc.
  • Windows: Numeric index (e.g., %1, %2, %11)
  • Generic: Interface name or scope identifier

Examples of Zone ID Usage:

  • ping fe80::1%eth0 (specify which interface to ping through)
  • ssh [fe80::1%en0] (SSH to link-local address on en0)
  • curl http://[fe80::1%wlan0]:8080 (HTTP with zone in URL)
  • nc fe80::1%2 80 (netcat with numeric zone ID)

URL Encoding:

In URLs, the % sign must be percent-encoded as %25:

  • Correct: http://[fe80::1%25eth0]:80
  • Incorrect: http://[fe80::1%eth0]:80 (browser interprets % as URL encoding)

Common Errors:

  • "Invalid argument": Missing zone ID for link-local address
  • "Network unreachable": Wrong zone ID or interface down
  • "No route to host": Zone ID doesn't match actual interface

Programming Considerations:

  • getaddrinfo() requires zone ID in sin6_scope_id field for link-local
  • Zone IDs are system-specific (interface names differ across hosts)
  • Applications should accept zone IDs in user input for link-local addresses
  • Some libraries auto-parse zone IDs from address%zone format

Why Global Addresses Don't Need Zones:

Global unicast addresses (2000::/3) are globally unique, so there's no ambiguity about which interface to use. The routing table determines the outbound interface automatically.