IPv6 ULA generator
Generate a RFC 4193 unique local IPv6 address prefix.
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About the ipv6 ula generator
Generates an RFC 4193 unique local address prefix with a properly random 40-bit global identifier, plus the /64 subnet and first usable address. The IPv6 equivalent of RFC 1918 private space, intended for networks that never route to the internet.
Frequently asked questions
Why must the global ID be random?
So two independently built networks do not collide when they are later merged or joined by VPN. Picking a memorable value like fd00::/48 defeats the entire mechanism — and many people pick exactly that.
Can ULA addresses reach the internet?
No. They are not routed on the public internet by design. Hosts needing outbound access require a global address as well, which is normal in dual-address IPv6 deployments.