shadow1ng/fscan · error

netbios_session_connect_failed: %w

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.

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,
	}

View on GitHub (pinned to 95cc12e753)

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.