title: Web Scraping from B3 iFrame
body: <p>I am trying to download some data from BM&amp;FBOVESPA reference rates page. There is an iframe in there, which is as follows:</p>
  <p><a href="https://www2.bmf.com.br/pages/portal/bmfbovespa/lumis/lum-sistema-pregao-ptBR.asp?Data=23/09/2021&amp;Mercadoria=DI1" rel="nofollow noreferrer">https://www2.bmf.com.br/pages/portal/bmfbovespa/lumis/lum-sistema-pregao-ptBR.asp?Data=23/09/2021&amp;Mercadoria=DI1</a></p>
  <p>Here is my code, which is returning a DF with only <code>NA</code>:</p>
  <pre><code>library(rvest)
  library(stringr)
  
  html_url &lt;- &quot;https://www2.bmf.com.br/pages/portal/bmfbovespa/lumis/lum-sistema-pregao-ptBR.asp?Data=23/09/2021&amp;Mercadoria=DI1&quot;
  
  html &lt;- read_html(html_url)
  
  data &lt;- html %&gt;%
    html_nodes(&quot;td&quot;) %&gt;%
    html_text() %&gt;%
    str_replace(&quot;,&quot;, &quot;.&quot;) %&gt;%
    as.numeric()
  </code></pre>
  <p>How can I download the data from this page?</p>