Controlling Nebula locally with nebula ctl

Nebula serves two local APIs, configured in the local_api section:

• The control socket, used by nebula ctl, runs the same commands as the SSH debug console without having to set up sshd. It is on by default.
• The info API answers "who is this?" for overlay addresses over HTTP, for other programs on the host. It is off by default.

Running commands with nebula ctl

nebula ctl connects to a Nebula already running on the same machine. Run it as root, as the user Nebula runs as, or as a member of local_api.control.group. On Windows, run it from an elevated prompt.

$ sudo nebula ctl list-hostmap
$ sudo nebula ctl identity 10.128.1.2
name: web01
vpn addrs: 10.128.1.2
networks: 10.128.1.2/16
unsafe networks:
groups: servers, web
fingerprint: 6d1f...
issuer: 4f0b...
not before: 2026-01-05T17:00:00Z
not after: 2027-01-05T16:59:59Z
cert version: 2

nebula ctl with no command, or nebula ctl help, lists the available commands. They are the same commands as the SSH debug console, except logout. nebula ctl help <command> or nebula ctl <command> -h shows a command's flags.

Finding the socket

nebula ctl needs to know where the control socket is. It looks, in order:

1. At the path given with -socket.
2. At local_api.control.socket in the config given with -config, or else in a config.yml or config.yaml next to the nebula binary.
3. At the default path, /var/run/nebula/ctl.sock, or \\.\pipe\ProtectedPrefix\Administrators\nebula-ctl on Windows.

If Nebula uses a non-default socket, point nebula ctl at the same config Nebula runs with:

$ sudo nebula ctl -config /etc/nebula/config.yml print-tunnel -pretty 10.128.1.2

-config and -socket may come before or after the command. nebula -config /etc/nebula/config.yml ctl <command> works too.

Output and exit codes

Commands print human readable text by default. Add -json for compact JSON, or -pretty for indented JSON. print-tunnel, print-relays, and query-lighthouse only have JSON output, and require -json or -pretty.

In JSON, commands that act rather than report, such as close-tunnel or reload, print {"ok":true,"reason":"..."}, or "ok":false with the reason when they refuse.

nebula ctl exits 0 on success and 1 on any failure. nebula ctl reload prints the outcome of the reload, and exits 1 when the new config did not load or part of it failed to apply, but not when it only needs a restart.

The control socket serves up to 8 connections at once.

Looking up identities with the info API

The info API lets programs on the host ask Nebula which certificate is behind an overlay address, for example to authorize a connection by the peer's Nebula groups. Enable it with a socket path:

local_api:
  info:
    enabled: true
    socket: /var/run/nebula/info.sock
    group: nebula-info

It serves these requests:

Request	Answers
GET /v1/identity	This node's identity
GET /v1/identity/<vpn addr>[:port]	The identity of the host with an established tunnel that owns the address
GET /v1/identity/pem	This node's certificate, as {"pem": "-----BEGIN NEBULA CERTIFICATE-----..."}
GET /v1/identity/<vpn addr>[:port]/pem	That host's certificate, the same way

A port on the address is accepted and ignored, so a program can pass the remote address of a connection as it is. Write an IPv6 address with a port as [addr]:port. Add ?pretty to any request to indent the JSON.

$ curl --unix-socket /var/run/nebula/info.sock 'http://localhost/v1/identity/10.128.1.2:443?pretty'
{
    "name": "web01",
    "vpnAddrs": [
        "10.128.1.2"
    ],
    "networks": [
        "10.128.1.2/16"
    ],
    "unsafeNetworks": [],
    "groups": [
        "servers",
        "web"
    ],
    "fingerprint": "6d1f...",
    "issuer": "4f0b...",
    "notBefore": "2026-01-05T17:00:00Z",
    "notAfter": "2027-01-05T16:59:59Z",
    "certVersion": 2
}

Lists are empty rather than null. Errors are JSON as well, {"error": "..."}, with these statuses:

• 400: the address could not be parsed, the query was not pretty, or the request had a body.
• 404: there is no established tunnel for the address, the address is outside this node's networks, or the path is unknown.
• 405: the method was not GET.

Caution

The info API tells you which certificate owns an overlay address. It only tells you who sent a connection if that connection arrived on the Nebula interface. Nebula drops packets whose source address the sender's certificate does not allow, but a connection that arrived on any other interface was never checked by Nebula. Before authorizing a connection with the info API, confirm it came in on the Nebula interface.

The info API only answers for established tunnels and addresses inside this node's own overlay networks. An address in another overlay network could arrive through a peer's unsafe network, so it is never answered.

The info API is read-only and only serves certificate identity, so it is fine to open it to a group, or to every user on the host with socket_mode: "0666". Never open the control socket that way.

Windows

On Windows the info API is a named pipe. Name it under \\.\pipe\ProtectedPrefix\Administrators\, so that only an administrator can create it and another program cannot take the name first. A program connecting as a member of local_api.info.group must open the pipe asking for exactly FILE_READ_DATA | FILE_WRITE_DATA | FILE_READ_ATTRIBUTES | READ_CONTROL | SYNCHRONIZE. Asking for GENERIC_READ or GENERIC_WRITE is refused.