IPv6 ULA ジェネレーター
「IPv6 ULA ジェネレーター」はコード、データと QRに使えるブラウザツールです。入力内容と結果は通常この端末内で処理され、登録は必要ありません。
使い方
使い方
- Choose whether to create a fresh random /48 prefix or enter one you already have.
- Generate a sample host address inside the prefix when you need a concrete endpoint.
- Copy the prefix or address for your network plan, configuration, or documentation.
What RFC 4193 ULA space means
Unique Local Addresses use fc00::/7 and are intended for local communication that is not expected to be routed across the public Internet. This generator creates the locally assigned fd00::/8 form with a random 40-bit global ID, producing a /48 site prefix.
A planning value, not a network reservation
Generated values are random examples for private network planning. The page does not check collisions, configure routers, advertise routes, or guarantee that a prefix is unique across every network you may connect to. Keep the prefix stable once you deploy it and avoid reusing another network’s prefix.
Browser-local generation and copying
Random bits come from the browser Web Crypto API and the result stays in this page. Copying uses the browser clipboard permission. Do not use a ULA as a replacement for a globally routed address when Internet reachability is required.
よくある質問
あわせて知りたいこと
What is the difference between a ULA prefix and an address?
A /48 ULA prefix identifies the private site range, such as fd7a:3c91:5e20::/48. An address adds a subnet and interface identifier inside that range, such as fd7a:3c91:5e20::1.
Why does the result start with fd?
RFC 4193 reserves fc00::/7 for Unique Local Addresses. The locally assigned range uses the fd00::/8 half, while fc00::/8 is reserved for future centrally assigned use.
Can I route a ULA over the public Internet?
No. ULA space is for local or private routing. Use a provider-assigned global unicast prefix when an address must be reachable across the public Internet.
Does this prove the prefix is unique?
No. It uses random generation to make collisions unlikely, but it cannot inspect other networks. Check your existing address plans before connecting networks or merging sites.