title: Failed to add the host to the list of known hosts, how to debug
body: <p>Try to ssh using -v. The output is:</p>
  
  <pre><code>ccc@es-chen:~$ ssh cccadmin@ccchost -A -X -v
  OpenSSH_5.9p1 Debian-5ubuntu1.7, OpenSSL 1.0.1 14 Mar 2012
  debug1: Reading configuration data /home/ccc/.ssh/config
  debug1: /home/ccc/.ssh/config line 11: Applying options for *
  debug1: Reading configuration data /etc/ssh/ssh_config
  debug1: /etc/ssh/ssh_config line 19: Applying options for *
  debug1: Connecting to ccchost [10.36.64.12] port 22.
  debug1: Connection established.
  debug1: identity file /home/ccc/.ssh/id_rsa type 1
  debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
  debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
  debug1: identity file /home/ccc/.ssh/id_rsa-cert type -1
  debug1: identity file /home/ccc/.ssh/id_dsa type -1
  debug1: identity file /home/ccc/.ssh/id_dsa-cert type -1
  debug1: identity file /home/ccc/.ssh/id_ecdsa type -1
  debug1: identity file /home/ccc/.ssh/id_ecdsa-cert type -1
  debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1
  debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1 pat OpenSSH*
  debug1: Enabling compatibility mode for protocol 2.0
  debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.7
  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: sending SSH2_MSG_KEX_ECDH_INIT
  debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
  debug1: Server host key: ECDSA 17:d5:07:c8:1f:80:2d:5a:95:9b:95:ce:31:de:54:5e
  The authenticity of host 'ccchost (10.36.64.12)' can't be established.
  ECDSA key fingerprint is 17:d5:07:c8:1f:80:2d:5a:95:9b:95:ce:31:de:54:5e.
  Are you sure you want to continue connecting (yes/no)? yes
  Failed to add the host to the list of known hosts (/home/ccc/.ssh/known_hosts).
  debug1: ssh_ecdsa_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,password
  debug1: Next authentication method: publickey
  debug1: Offering RSA public key: /home/ccc/.ssh/id_rsa
  debug1: Authentications that can continue: publickey,password
  debug1: Trying private key: /home/ccc/.ssh/id_dsa
  debug1: Trying private key: /home/ccc/.ssh/id_ecdsa
  debug1: Next authentication method: password
  cccadmin@ccchost's password: 
  debug1: Authentications that can continue: publickey,password
  Permission denied, please try again.
  cccadmin@ccchost's password: 
  debug1: Authentications that can continue: publickey,password
  Permission denied, please try again.
  cccadmin@ccchost's password: 
  debug1: Authentications that can continue: publickey,password
  debug1: No more authentication methods to try.
  Permission denied (publickey,password).
  </code></pre>
  
  <p>How to figure out why? Any ideas? thanks</p>