在打通虛擬機之間的ssh無密碼登錄時出現的問題，每次嘗試登陸都會提示錯誤：Permission denied 。歷時一天多，我終於把問題搞定，期間百度了很多人的方法，也受到啟發，其實是很簡單的一個原理，今天就跟大家一起分享下吧，也算是做個記錄。
開始走了很多誤區，重復設置sshd_config,vsftpd.conf 等等文件，找不出問題出在哪。
因為 ssh localhost 時 可以連通，ssh 192.168.1.10時就不行
ssh localhost 如下
ssh 192.168.1.10如下
總結：因為localhost是本機，本機有正確的密鑰，所以能連上，而那個則沒有，因為來沒有傳，也沒辦法傳，因為現在無法連通，所以現在要解決連通問題。
后來通過 ssh -v 查看了連接記錄，有所收獲，對比如下
ssh localhost(只截取了一部分)
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<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: Host 'localhost' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:2
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found
debug1: Unspecified GSS failure. Minor code may provide more information
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/identity
debug1: Offering public key: /root/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 277
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
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
Last login: Wed May 13 01:13:48 2015 from localhost
ssh 192,168,1,10
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<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: Host '192.168.1.10' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:1
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found
debug1: Unspecified GSS failure. Minor code may provide more information
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/identity
debug1: Offering public key: /root/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Trying private key: /root/.ssh/id_ecdsa
debug1: No more authentication methods to try.
Permission denied (publickey,gssapi-keyex,gssapi-with-mic).
這句很重要，說明除了驗證密鑰的方式，沒有其他方式可以選擇，而現在沒傳公鑰所以鏈接是注定失敗的 ，那么我們就要添加一個方式就是 密碼驗證方式，到這里我就恍然大悟了，需要設置passwordauthority yes ！！！！
解決方式：
打開ssh配置文件修改
命令：vim /etc/ssh/sshd_config
其中有一項 passwordauthority ，這個要注意了，我們設置無密碼登錄就需要把本機的公鑰傳到服務器上去，加入服務器的authorized_keys文件里，才可以訪問到此服務器，如果passwordauthority no 就不允許ssh進行密碼訪問，所以這個設置不能過早的設置。
正確的順序是：
1、passwordauthority yes；
2、把公鑰id_rsa.pub傳到服務器上，命令：scp ~/.ssh/id_rsa.pub 遠程用戶名@遠程服務器IP:~/
3、把公鑰追加到authorized_keys里,命令：cat ~/id_rsa.pub >> ~/.ssh/authorized_keys
4、更改授權，命令：chmod 600 ~/.ssh/authorized_keys
5、passwordauthority no //此時再更改為不許密碼登陸，使用密鑰即可。
反思：除了跟着網上步驟一步步做，還需要自己思考，知道how還要知道why，這樣才能把握住問題，靈活應變。
ps:最近挺累的，真的，尤其，夏天又到了，看着別的菇涼穿的美美的，我好想去逛街，啊啊，好想穿着裙子美美的出去玩耍~~%>_<%，哎，but,i can't !
不過還好，堅持學習的這段時間，每天都有進步，也都有新的收獲，加油吧。gogo!!
over 成功連接~！！