I authenticated with hadoop-admin user.
hdfs dfsadmin -fetchImage ./output
command works well.
However, when I try to do this with curl command,
curl https://{namenode_address}:9470/imagetransfer?getimage=1&txid=latest
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<title>Error 401 Authentication required</title>
</head>
<body><h2>HTTP ERROR 401</h2>
<p>Problem accessing /imagetransfer. Reason:
<pre> Authentication required</pre></p>
</body>
</html>
Which authentication is needed additionally?