shadow1ng/fscan · error

netbios_session_connect_failed

Error message

netbios_session_connect_failed: %w

What it means

Guard in queryNetBIOSSession: session.DialTCP failed to open a TCP connection to host:139 within the configured timeout. The NetBIOS session service is unreachable (closed port, filtered host, or timeout), so no SMB session probe can be performed.

Solutions

1. Verify TCP 139 is open on the target
2. Increase the module timeout
3. Check for firewall/IPS blocking the session-service port

When it happens

Trigger: Thrown at plugins/services/netbios.go:196 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/b10b0664a89db3ff. Report an issue: GitHub.

Appendix: source

Thrown at plugins/services/netbios.go:196

		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])
}

// queryNetBIOSSession 查询NetBIOS会话服务(TCP 139)
func (p *NetBIOSPlugin) queryNetBIOSSession(ctx context.Context, host string, session *common.ScanSession) (*NetBIOSInfo, error) {
	target := fmt.Sprintf("%s:139", host)

	conn, err := session.DialTCP(ctx, "tcp", target, session.Config.ModuleTimeout())
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("netbios_session_connect_failed"), err)
	}
	defer func() { _ = conn.Close() }()

	_ = conn.SetDeadline(time.Now().Add(session.Config.ModuleTimeout()))

	// 发送SMB协商数据包
	smbNegotiate1 := []byte{
		0x00, 0x00, 0x00, 0x85, 0xFF, 0x53, 0x4D, 0x42, 0x72, 0x00, 0x00, 0x00, 0x00, 0x18, 0x53, 0xC8,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFE,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x62, 0x00, 0x02, 0x50, 0x43, 0x20, 0x4E, 0x45, 0x54, 0x57, 0x4F,
		0x52, 0x4B, 0x20, 0x50, 0x52, 0x4F, 0x47, 0x52, 0x41, 0x4D, 0x20, 0x31, 0x2E, 0x30, 0x00, 0x02,
		0x4C, 0x41, 0x4E, 0x4D, 0x41, 0x4E, 0x31, 0x2E, 0x30, 0x00, 0x02, 0x57, 0x69, 0x6E, 0x64, 0x6F,
		0x77, 0x73, 0x20, 0x66, 0x6F, 0x72, 0x20, 0x57, 0x6F, 0x72, 0x6B, 0x67, 0x72, 0x6F, 0x75, 0x70,
		0x73, 0x20, 0x33, 0x2E, 0x31, 0x61, 0x00, 0x02, 0x4C, 0x4D, 0x31, 0x2E, 0x32, 0x58, 0x30, 0x30,
		0x32, 0x00, 0x02, 0x4C, 0x41, 0x4E, 0x4D, 0x41, 0x4E, 0x32, 0x2E, 0x31, 0x00, 0x02, 0x4E, 0x54,
		0x20, 0x4C, 0x4D, 0x20, 0x30, 0x2E, 0x31, 0x32, 0x00,
	}

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