shadow1ng/fscan · error

netbios_name_connect_failed: %w

Error message

netbios_name_connect_failed: %w

What it means

Guard in queryNetBIOSNames: net.DialTimeout failed to open a UDP 'connection' to host:137 within the module timeout, so the name-service query was never sent. Typically the host is unreachable, the port is filtered, or the timeout is too short for the path.

Source

Thrown at plugins/services/netbios.go:169

	return strings.Join(parts, " ")
}

// queryNetBIOSNames 查询NetBIOS名称服务(UDP 137)
func (p *NetBIOSPlugin) queryNetBIOSNames(host string, config *common.Config, state *common.State) (*NetBIOSInfo, error) {
	// NetBIOS名称查询数据包
	queryPacket := []byte{
		0x66, 0x66, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x20, 0x43, 0x4B, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41,
		0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41,
		0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x00, 0x00, 0x21, 0x00, 0x01,
	}

	target := fmt.Sprintf("%s:137", host)

	conn, err := net.DialTimeout("udp", target, config.ModuleTimeout())
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("netbios_name_connect_failed"), err)
	}
	state.IncrementUDPPacketCount()
	defer func() { _ = conn.Close() }()

	_ = conn.SetDeadline(time.Now().Add(config.ModuleTimeout()))

	_, err = conn.Write(queryPacket)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("netbios_query_send_failed"), err)
	}

	response := make([]byte, 1024)
	n, err := conn.Read(response)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("netbios_response_read_failed"), err)
	}

	return p.parseNetBIOSNames(response[:n])

View on GitHub (pinned to 95cc12e753)

Solutions

1. Verify host reachability and that UDP 137 is not filtered by a firewall
2. Increase the module timeout for slow links
3. Confirm the target is a Windows/Samba host that answers NetBIOS

When it happens

Trigger: Thrown at plugins/services/netbios.go:169 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of shadow1ng/fscan@95cc12e753 (2026-09-06). Data as JSON: /api/errors/5a966179bd9aa327. Report an issue: GitHub.