title: How to filter custom protocol packet?
body: <p>I want to set filter, of "ether type" which value is equal to <code>0xe188</code>. 
  How to write this filter?</p>
  
  <p>My filter is <code>"ether type 0xe188"</code>, but it compiles with ERROR:</p>
  
  <pre><code>if(pcap_compile(fp, &amp;fcode,"ether proto 0xe188", 1, NetMask) &gt;= 0)
      pcap_setfilter(fp, &amp;fcode);
  </code></pre>