title: ssh cannot use the IdentityFile config in file ~/.ssh/config
body: <p>client：Mac 10.8，server：Ubuntu 10.04 LTS 64bit</p>
  
  <p>I use '<strong>ssh-keygen -t rsa</strong>' generate public/private keys.</p>
  
  <p>First, I input: <strong>ssh -i /Users/phenix/.ssh/poponet_rsa root@popo.net</strong>, I can login to the server with the private key 'poponet_rsa'</p>
  
  <p>Next, I create a config file: <strong>/Users/phenix/.ssh/config</strong>, with content:</p>
  
  <pre><code>Host popo
      Hostname popo.net
      User root
      PreferredAuthentications publickey
      IdentityFile /Users/phenix/.ssh/poponet_rsa
  </code></pre>
  
  <p>and I input <strong>ssh root@popo.net</strong>, the Terminal ask me the password.</p>
  
  <p>Next, I change <strong>poponet_rsa</strong> filename to <strong>id_rsa</strong>, and input <strong>ssh root@popo.net</strong>, OK, I login.</p>
  
  <p>My question: <strong>ssh cannot use the IdentityFile config in file ~/.ssh/config, why?</strong></p>
  
  <pre><code>$ ssh -vvv root@popo.net
  OpenSSH_5.9p1, OpenSSL 0.9.8r 8 Feb 2011
  debug1: Reading configuration data /Users/phenix/.ssh/config
  debug1: /Users/phenix/.ssh/config line 1: Applying options for popo.net
  debug1: /Users/phenix/.ssh/config line 2: Applying options for popo.net
  debug1: Reading configuration data /etc/ssh_config
  debug1: /etc/ssh_config line 20: Applying options for *
  debug2: ssh_connect: needpriv 0
  debug1: Connecting to popo.net [111.111.111.111] port 22.
  debug1: Connection established.
  debug3: Incorrect RSA1 identifier
  debug3: Could not load "/Users/phenix/.ssh/id_rsa" as a RSA1 public key
  debug1: identity file /Users/phenix/.ssh/id_rsa type -1
  debug1: identity file /Users/phenix/.ssh/id_rsa-cert type -1
  debug1: identity file /Users/phenix/.ssh/id_dsa type -1
  debug1: identity file /Users/phenix/.ssh/id_dsa-cert type -1
  debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3p1 Debian-3ubuntu7
  debug1: match: OpenSSH_5.3p1 Debian-3ubuntu7 pat OpenSSH*
  debug1: Enabling compatibility mode for protocol 2.0
  debug1: Local version string SSH-2.0-OpenSSH_5.9
  debug2: fd 3 setting O_NONBLOCK
  debug3: load_hostkeys: loading entries for host "popo.net" from file "/Users/phenix/.ssh/known_hosts"
  debug3: load_hostkeys: found key type RSA in file /Users/phenix/.ssh/known_hosts:1
  debug3: load_hostkeys: loaded 1 keys
  debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-rsa-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-rsa
  debug1: SSH2_MSG_KEXINIT sent
  debug1: SSH2_MSG_KEXINIT received
  debug2: kex_parse_kexinit: **too much init, i delete them.**
  debug2: mac_setup: found hmac-md5
  debug1: kex: server-&gt;client aes128-ctr hmac-md5 none
  debug2: mac_setup: found hmac-md5
  debug1: kex: client-&gt;server aes128-ctr hmac-md5 none
  debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024&lt;1024&lt;8192) sent
  debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
  debug2: dh_gen_key: priv key bits set: 135/256
  debug2: bits set: 468/1024
  debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
  debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
  debug1: Server host key: RSA xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
  debug3: load_hostkeys: loading entries for host "popo.net" from file "/Users/phenix/.ssh/known_hosts"
  debug3: load_hostkeys: found key type RSA in file /Users/phenix/.ssh/known_hosts:1
  debug3: load_hostkeys: loaded 1 keys
  debug3: load_hostkeys: loading entries for host "111.111.111.111" from file "/Users/phenix/.ssh/known_hosts"
  debug3: load_hostkeys: found key type RSA in file /Users/phenix/.ssh/known_hosts:1
  debug3: load_hostkeys: loaded 1 keys
  debug1: Host 'popo.net' is known and matches the RSA host key.
  debug1: Found key in /Users/phenix/.ssh/known_hosts:1
  debug2: bits set: 516/1024
  debug1: ssh_rsa_verify: signature correct
  debug2: kex_derive_keys
  debug2: set_newkeys: mode 1
  debug1: SSH2_MSG_NEWKEYS sent
  debug1: expecting SSH2_MSG_NEWKEYS
  debug2: set_newkeys: mode 0
  debug1: SSH2_MSG_NEWKEYS received
  debug1: Roaming not allowed by server
  debug1: SSH2_MSG_SERVICE_REQUEST sent
  debug2: service_accept: ssh-userauth
  debug1: SSH2_MSG_SERVICE_ACCEPT received
  debug2: key: /Users/phenix/.ssh/id_rsa (0x0)
  debug2: key: /Users/phenix/.ssh/id_dsa (0x0)
  debug1: Authentications that can continue: publickey,password
  debug3: start over, passed a different list publickey,password
  debug3: preferred publickey,keyboard-interactive,password
  debug3: authmethod_lookup publickey
  debug3: remaining preferred: keyboard-interactive,password
  debug3: authmethod_is_enabled publickey
  debug1: Next authentication method: publickey
  debug1: Trying private key: /Users/phenix/.ssh/id_rsa
  debug1: key_parse_private_pem: PEM_read_PrivateKey failed
  debug1: read PEM private key done: type &lt;unknown&gt;
  debug2: no passphrase given, try next key
  debug1: Trying private key: /Users/phenix/.ssh/id_dsa
  debug3: no such identity: /Users/phenix/.ssh/id_dsa
  debug2: we did not send a packet, disable method
  debug3: authmethod_lookup password
  debug3: remaining preferred: ,password
  debug3: authmethod_is_enabled password
  debug1: Next authentication method: password
  root@popo.net's password: 
  </code></pre>