slackhq/nebula · error

unknown address type %v

Error message

unknown address type %v

What it means

addIp dispatches on the address family of the provided CIDR: Is4 path uses SIOCAIFADDR, Is6 path uses SIOCAIFADDR_IN6. If the address is neither recognized IPv4 nor IPv6 (or the CIDR type is unexpected), the library returns 'unknown address type %v'.

Source

Thrown at overlay/tun_netbsd.go:300

		}
		req.Lifetime = addrLifetime{
			Vltime: 0xffffffff,
			Pltime: 0xffffffff,
		}

		s, err := unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, unix.IPPROTO_IP)
		if err != nil {
			return err
		}
		defer syscall.Close(s)

		if err := ioctl(uintptr(s), SIOCAIFADDR_IN6, uintptr(unsafe.Pointer(&req))); err != nil {
			return fmt.Errorf("failed to set tun address %s: %s", cidr.Addr().String(), err)
		}
		return nil
	}

	return fmt.Errorf("unknown address type %v", cidr)
}

func (t *tun) Activate() error {
	mode := int32(unix.IFF_BROADCAST)
	err := ioctl(uintptr(t.fd), TUNSIFMODE, uintptr(unsafe.Pointer(&mode)))
	if err != nil {
		return fmt.Errorf("failed to set tun device mode: %w", err)
	}

	v := 1
	err = ioctl(uintptr(t.fd), TUNSIFHEAD, uintptr(unsafe.Pointer(&v)))
	if err != nil {
		return fmt.Errorf("failed to set tun device head: %w", err)
	}

	err = t.doIoctlByName(unix.SIOCSIFMTU, uint32(t.MTU))
	if err != nil {
		return fmt.Errorf("failed to set tun mtu: %w", err)

View on GitHub (pinned to dd8f660c0a)

Solutions

1. Check the configured tun address parses to a valid IPv4 or IPv6 CIDR
2. Log/inspect the %v value in the error to see what address was actually supplied
3. Fix config so the address is explicitly 4 or 6 (e.g. 10.0.0.1/24 or fd00::1/64)

Example fix

// before
"tun": { "dev": "tun0", "addr": "" }
// after
"tun": { "dev": "tun0", "addr": "10.0.0.1/24" }

if !(cidr.Addr().Is4() || cidr.Addr().Is6()) {
    return fmt.Errorf("unsupported tun address family: %v", cidr)
}

When it happens

Trigger: addIp is called with a CIDR value that is neither 4- nor 6-family per the library's address type (e.g. a zero/unset address, or a mixed/uninitialized value).

Common situations: Config yielding an empty or malformed address that parses as an unknown family; passing a custom/foreign address type into the API.

Related errors

• a device name in the format of /dev/tunN must be specified
• failed to set tun address %s: %s
• newTunFromFd not supported in NetBSD
• error closing tun file: %w
• failed to get syscall conn for tun: %w

AI-assisted analysis of slackhq/nebula@dd8f660c0a (2026-09-03). Data as JSON: /api/errors/17c43f72ea35fbde. Report an issue: GitHub.