JAEN

IPv6 ULA Generator

Generate an RFC 4193-compliant IPv6 Unique Local Address (ULA).

Input data is processed in your browser
Data is never sent to a server

Tool

What is the IPv6 ULA Generator?

This tool generates an RFC 4193-compliant IPv6 Unique Local Address. It computes a random, low-collision Global ID using a SHA-1 hash, then combines it with a Subnet ID and Interface ID to produce a complete example address.

Key Features

  • RFC 4193-compliant Global ID generation (SHA-1 based)
  • /48 ULA prefix display
  • Manually editable or randomizable Subnet ID (16-bit) and Interface ID (64-bit)
  • Copy button for each value

When This Comes in Handy

  • Designing a private IPv6 addressing scheme for a corporate network or home lab
  • Learning how ULA components (Global ID, Subnet ID, Interface ID) fit together by seeing them generated live
  • Getting a ready-to-use example IPv6 address for network equipment configuration

How to Use

  1. Click "Generate New ULA" to produce a /48 ULA prefix, including a Global ID computed via a SHA-1-based hash.
  2. Enter a Subnet ID (16-bit) manually, or click "Randomize" to generate a new one.
  3. The Interface ID (64-bit) can likewise be entered manually or randomized.
  4. Copy the resulting full example address using the copy button.

FAQ

What is a ULA (Unique Local Address)?

A ULA is the IPv6 equivalent of an IPv4 private address range (like 10.0.0.0/8), defined in RFC 4193. It uses the fc00::/7 range and is intended for use within an organization or site, not for routing on the public internet.

Why is the fd00::/8 range used?

Within the ULA prefix fc00::/7, setting the L (Local) bit to 1 gives fd00::/8, indicating a locally generated Global ID. L=0 (fc00::/8) is reserved for future use and currently unused.

How is the Global ID generated?

Following RFC 4193's recommended procedure, the current time is concatenated with a random 64-bit value, hashed with SHA-1, and the lowest 40 bits of the result are used as the Global ID. This makes collisions between independently generated IDs extremely unlikely.

Can I use a generated ULA on a real network?

Yes. A ULA can be used as a private IPv6 address on a real corporate or home network. However, since ULAs aren't routed on the public internet, you'll still need a separate global address or NAT for external communication.

More Tools in This Category

Text

Count, clean, compare, and transform text in the browser.

Generators

Generate UUIDs, hashes, passwords, QR codes, and more.

Web

Inspect user agents, IP details, meta tags, and CSS gradients.

YAML

Format, validate, and diff YAML configuration files.