shadow1ng/fscan · error

netbios_name_connect_failed

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.

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.

Appendix: 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])

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