Automatic Domains (2n6.me)

Every Aleph Cloud instance automatically receives a free, deterministic URL under *.2n6.me. These URLs are derived from the instance hash — no DNS setup or configuration is required.

Each URL is composed of four memorable BIP-39 words, for example:

abandon-ability-able-about.2n6.me

The URL is deterministic: the same instance hash always produces the same subdomain. You can compute it before the VM is even running.

Finding Your VM's URL

From the API

The 2n6.me gateway exposes a public API at api.2n6.me. You can look up your instance's automatic domain by its hash:

curl https://api.2n6.me/api/hash/YOUR_INSTANCE_HASH

{
  "instance_hash": "abc123...",
  "subdomain": "abandon-ability-able-about",
  "url": "abandon-ability-able-about.2n6.me",
  "ipv6": "2001:db8::1",
  "active": true
}

You can also look up an instance by its subdomain:

curl https://api.2n6.me/api/lookup/abandon-ability-able-about

{
  "subdomain": "abandon-ability-able-about",
  "url": "abandon-ability-able-about.2n6.me",
  "instance_hash": "abc123...",
  "ipv6": "2001:db8::1",
  "active": true
}

To check overall gateway status:

curl https://api.2n6.me/api/status

{
  "instance_count": 1234,
  "route_count": 567,
  "last_sync_time": 1700000000.0,
  "domain": "2n6.me"
}

Computing It Locally

The subdomain is derived deterministically from the instance hash. Here's a minimal Python snippet:

# Download the BIP-39 English wordlist (2048 words)
# https://github.com/bitcoin/bips/blob/master/bip-0039/english.txt

def hash_to_subdomain(instance_hash: str, wordlist: list[str]) -> str:
    h = int(instance_hash, 16)
    bits = h >> (256 - 44)       # top 44 bits of the 256-bit hash
    w4 = bits & 0x7FF; bits >>= 11
    w3 = bits & 0x7FF; bits >>= 11
    w2 = bits & 0x7FF; bits >>= 11
    w1 = bits & 0x7FF
    return f"{wordlist[w1]}-{wordlist[w2]}-{wordlist[w3]}-{wordlist[w4]}"

Since it's deterministic, you can compute the URL before deploying, or use it in scripts and automation without querying the API.

Accessing Your VM

HTTPS (SNI Passthrough)

The 2n6.me gateway performs Layer 4 SNI passthrough — it routes TLS connections to your VM based on the Server Name Indication (SNI) in the TLS handshake, without terminating TLS itself.

WARNING

Your VM must serve its own TLS certificate. The gateway does not terminate TLS for you.

The easiest way to handle this is to run a reverse proxy inside your VM that provides automatic TLS. Caddy is recommended — it obtains and renews Let's Encrypt certificates automatically with zero configuration:

# Inside your VM
sudo caddy reverse-proxy --from your-subdomain.2n6.me --to localhost:8080

HTTP

Plain HTTP also works. The gateway routes HTTP requests based on the Host header. No TLS setup is needed on the VM side for HTTP traffic.

Sync Delay

WARNING

New instances may take up to 5 minutes to become reachable via their 2n6.me URL. The gateway syncs with the Aleph network periodically.

Comparison with Custom Domains

Feature	Automatic Domain (2n6.me)	Custom Domain
DNS setup required	No	Yes (CNAME + TXT records)
URL format	word-word-word-word.2n6.me	yourdomain.com
Custom branding	No	Yes
TLS handling	SNI passthrough — VM serves its own cert	SNI passthrough — VM serves its own cert
IPv4	Yes (proxied via gateway)	Yes (proxied via CRN)
IPv6	Proxied via gateway	Direct to VM (no proxy)
SSH access	No	Yes (custom port on IPv4, direct port 22 on IPv6)

For branded domains or direct IPv6 access, see Instance Custom Domains.

Technical Reference

Subdomain Derivation Algorithm

The subdomain is derived from the instance hash as follows:

1. Parse the hex instance hash as a 256-bit integer.
2. Extract the top 44 bits (right-shift by 212).
3. Split into 4 chunks of 11 bits each, most significant first.
4. Each 11-bit value (0–2047) indexes into the BIP-39 English wordlist (2048 words).
5. Join the four words with hyphens.

Properties:

• Deterministic — the same hash always produces the same subdomain.
• Address space — 2^44 ≈ 17.6 trillion possible subdomains.
• Collision handling — if two hashes map to the same 44-bit prefix (extremely unlikely), the earlier instance (by timestamp) wins.

API Reference

All endpoints are read-only and CORS-enabled for GET requests from any origin.

Method	Path	Description
GET	/api/hash/{instance_hash}	Convert instance hash to subdomain, check if active
GET	/api/lookup/{subdomain}	Look up instance by 4-word subdomain
GET	/api/status	Gateway stats (instance count, route count, last sync time)
POST	/api/sync	Trigger manual sync (requires Authorization: Bearer <key>)

Base URL: https://api.2n6.me