title: Curl fails on sftp password authentication
body: <p>When I manually sftp using username and password it works fine, when using curl it fails. The same script will successfully connect to other servers with no problem. Because I can manually log in and other clients don't have a problem the server admins aren't much help.</p>
  
  <p>Here is the curl failed attempt:</p>
  
  <pre><code>curl -v --insecure --user username:password sftp://someurl.com
  
  *   Trying 199.187.***.***...
  * Connected to someurl.com (199.187.***.***) port 22 (#0)
  * SSH MD5 fingerprint: 6831eae63f230952a1775e0f67f80e7b
  * SSH authentication methods available: publickey,gssapi-keyex,gssapi with-mic,password
  * Using SSH public key file '(nil)'
  * Using SSH private key file ''
  * SSH public key authentication failed: Unable to extract public key from private key file: Unable to open private key file
  * Failure connecting to agent
  * Authentication failure
  * Closing connection 0
  curl: (67) Authentication failure
  </code></pre>
  
  <p>Here is the curl success on another url:</p>
  
  <pre><code>curl --insecure -v sftp://username:password@anotherurl.com
  
  * Rebuilt URL to: sftp://username:password@anotherurl.com/
  *   Trying 199.27.***.***...
  * Connected to anotherurl.com (199.27.***.***) port 22 (#0)
  * SSH MD5 fingerprint: bcf5632dc06c0353849b745822c4889a
  * SSH authentication methods available: password,publickey
  * Using SSH public key file '(nil)'
  * Using SSH private key file ''
  * SSH public key authentication failed: Unable to extract public key from private key file: Unable to open private key file
  * Initialized password authentication
  * Authentication complete
  drw-rw-rw-   3 user   group    2048 Sep 27  2014 .
  * Connection #0 to host anotherurl.com left intact
  </code></pre>
  
  <p>Here is the manual attempt on the original URL:</p>
  
  <pre><code>[ec2-user@ip-*** scripts]$ sftp -v username@someurl.com
  OpenSSH_6.2p2, OpenSSL 1.0.1k-fips 8 Jan 2015
  debug1: Reading configuration data /etc/ssh/ssh_config
  debug1: /etc/ssh/ssh_config line 50: Applying options for *
  debug1: Connecting to someurl.com [199.187.***.***] port 22.
  debug1: Connection established.
  debug1: identity file /home/ec2-user/.ssh/id_rsa type -1
  debug1: identity file /home/ec2-user/.ssh/id_rsa-cert type -1
  debug1: identity file /home/ec2-user/.ssh/id_dsa type -1
  debug1: identity file /home/ec2-user/.ssh/id_dsa-cert type -1
  debug1: identity file /home/ec2-user/.ssh/id_ecdsa type -1
  debug1: identity file /home/ec2-user/.ssh/id_ecdsa-cert type -1
  debug1: Enabling compatibility mode for protocol 2.0
  debug1: Local version string SSH-2.0-OpenSSH_6.2
  debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
  debug1: match: OpenSSH_5.3 pat OpenSSH_5*
  debug1: SSH2_MSG_KEXINIT sent
  debug1: SSH2_MSG_KEXINIT received
  debug1: kex: server-&gt;client aes128-ctr hmac-md5 none
  debug1: kex: client-&gt;server aes128-ctr hmac-md5 none
  debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024&lt;3072&lt;8192) sent
  debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
  debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
  debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
  debug1: Server host key: RSA 68:31:ea:e6:3f:23:09:52:a1:77:5e:0f:67:f8:0e:7b
  debug1: Host 'someurl.com' is known and matches the RSA host key.
  debug1: Found key in /home/ec2-user/.ssh/known_hosts:6
  debug1: ssh_rsa_verify: signature correct
  debug1: SSH2_MSG_NEWKEYS sent
  debug1: expecting SSH2_MSG_NEWKEYS
  debug1: SSH2_MSG_NEWKEYS received
  debug1: Roaming not allowed by server
  debug1: SSH2_MSG_SERVICE_REQUEST sent
  debug1: SSH2_MSG_SERVICE_ACCEPT received
  debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
  debug1: Next authentication method: gssapi-keyex
  debug1: No valid Key exchange context
  debug1: Next authentication method: gssapi-with-mic
  debug1: Unspecified GSS failure.  Minor code may provide more information
  No Kerberos credentials available
  
  debug1: Unspecified GSS failure.  Minor code may provide more information
  No Kerberos credentials available
  
  debug1: Unspecified GSS failure.  Minor code may provide more information
  
  
  debug1: Unspecified GSS failure.  Minor code may provide more information
  No Kerberos credentials available
  
  debug1: Next authentication method: publickey
  debug1: Trying private key: /home/ec2-user/.ssh/id_rsa
  debug1: Trying private key: /home/ec2-user/.ssh/id_dsa
  debug1: Trying private key: /home/ec2-user/.ssh/id_ecdsa
  debug1: Next authentication method: password
  username@someurl.com's password: 
  debug1: Authentication succeeded (password).
  Authenticated to someurl.com ([199.187.***.***]:22).
  debug1: channel 0: new [client-session]
  debug1: Requesting no-more-sessions@openssh.com
  debug1: Entering interactive session.
  debug1: Sending environment.
  debug1: Sending env LANG = en_US.UTF-8
  debug1: Sending subsystem: sftp
  Connected to someurl.com.
  sftp&gt; ls
  incoming  
  sftp&gt; 
  </code></pre>
  
  <p>Any help from those smarter-than-me people would be greatly appreciated. </p>