How nullcipher recognises it
Eight groups of up to four hex digits, or fewer with one :: compression, optionally ending in an IPv4 address or a %zone. ::1 and :: are skipped. Times like 12:30:45 and MAC addresses do not parse as IPv6.
This is the rule text of the “IPv6 address” detector in the masking engine, copied from the engine when this page was built. Detectors run in a fixed order and, where two overlap, the earlier one wins.
Example (fake)
2001:db8::8a2e:370:7334nullcipher replaces it with [IPV6_1]. 2001:db8::/32 is the prefix RFC 3849 reserves for documentation, so this address is never routed on the internet.
Why it matters in an AI chat
An IP address is not a credential, but it points at a specific connection. A server's address tells a reader exactly which machine to probe; a home connection's address is tied to one subscriber and often a rough location.
IPv6 addresses can be long-lived and specific to one device rather than a whole household, depending on how the device and network assign them.
When you ask an AI about an error, the address itself rarely matters to the answer. A placeholder keeps the structure (same address, same placeholder) without the value.
If it already leaked
- There is nothing to revoke.
- For a server: make sure only the services you mean to expose are reachable on that address, and that anything private sits behind a firewall, because the address is now known.
- For a home or office connection there is usually nothing further to do; the address identifies the connection, not an account.
Sources
- RFC 3849: IPv6 Address Prefix Reserved for Documentation — checked 2026-09-23.
Open the full masking tool to mask a whole log, .env file or e-mail — every type at once — and restore the values in the AI's answer. Or see all 16 secret types and how to delete a chat you already sent.