UUID v2 Generator

What is UUID v2?

UUID v2 is the DCE Security variant defined in RFC 4122 (and retained in RFC 9562 for reference). It was designed by the Open Group for DCE/RPC to embed a POSIX user or group identifier directly into the UUID so that a receiver could authenticate the origin without a lookup.

It is effectively obsolete. Almost no modern system generates or consumes UUID v2. If you are starting a new project, use UUID v4 (random) or UUID v7 (time-ordered). This tool exists so that users with legacy enterprise systems can produce compatible identifiers.

Structure

Like v1, it uses a 60-bit timestamp, a 14-bit clock sequence, and a 48-bit node. The difference is that the time_low field is replaced by a 32-bit local identifier (a POSIX UID or GID), and the node's low byte holds the domain.

Field	Bits	Contents
local_id	32	POSIX UID, GID, or another domain-specific ID
time_mid	16	Middle 16 bits of the timestamp
time_hi_and_version	16	High 12 bits of timestamp + version (2)
clock_seq	14	Random per-process sequence
node	40 + 8	40 bits node + 8 bits domain

Domains

RFC 4122 defines three domain values:

0 ..." POSIX User ID. The local ID is a UID from /etc/passwd.

1 ..." POSIX Group ID. The local ID is a GID from /etc/group.

2 ..." "Other." Reserved for organization-specific use.

How to generate

Enter a local ID (a number) and choose the domain. Press Generate. The tool produces a valid v2 UUID in the canonical 8-4-4-4-12 format.

To generate several at once, change the count. Every UUID is different because the clock sequence and node are randomized.

FAQ

Why is UUID v2 so rare?

DCE/RPC lost to other RPC systems, and modern authentication handles user identity at a different layer. UUID v2 was solving a problem ..." mapping an authenticated user to a UUID ..." that today is solved by Kerberos, OAuth, and JWTs.

Does this tool produce UUIDs identical to other v2 generators?

The field layout and version/variant bits are correct. The timestamp, clock sequence, and node are randomly generated, so two generators will produce different UUIDs from the same inputs. That is correct behavior ..." v2 identifiers are meant to be unique per (timestamp, node, local ID).

Should I use UUID v2 in a new project?

No. Use v4 if you need pure randomness, or v7 if you need time-ordered IDs for a database. v2 has no advantage over either and is not supported by most libraries.

What is the "local ID" exactly?

In a DCE environment, it is the numeric user or group ID of the principal on whose behalf the request is being made. In practice, this is almost always a POSIX UID or GID (integers), which is what this tool accepts.