string conDDNS;
FbConnection conexaoDDNS;

 protected void Abrir_Fechar_Click(object sender, EventArgs e)
    {
        try
        {
            this.conDDNS = "DRIVER=InterBase/Firebird(r) driver;User=SYSDBA;Password=masterkey;Database=localhost:C:/AdCom/ADCOM.FDB";

            this.conexaoDDNS = new FbConnection(conDDNS);
            this.conexaoDDNS.Open();
            ListItem item = new ListItem("Conexão aberta");
            ListBox1.Items.Add(item);

            this.conexaoDDNS.Dispose();
            this.conexaoDDNS.Close();
            ListItem item2 = new ListItem("Conexão fechada");
            ListBox1.Items.Add(item2);

        }
        catch (Exception erro)
        {
            ListItem item = new ListItem(erro.ToString());
            ListBox1.Items.Add(item);
        }

    }