本地生成的的RSA密钥传需要传到远程主机相应用户家目录下的.ssh子目录下，注意该子目录的权限设置是有严格要求的：其所属用户当然是该用户，其权限应该是700, 即不允许其它用户进入并访问该目录；否则，无法自动登录的。

这种情况下，使用ssh 的-v参数显示详细消息大致如下：

$ ssh -v feng@myremote.host.net
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to myremote.host.net [50.116.14.251] port 22.
debug1: Connection established.
debug1: identity file /home/feng/.ssh/identity type -1
debug1: identity file /home/feng/.ssh/id_rsa type 1
debug1: identity file /home/feng/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
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 'myremote.host.net' is known and matches the RSA host key.
debug1: Found key in /home/feng/.ssh/known_hosts:8
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
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
Credentials cache file '/tmp/krb5cc_501' not found

debug1: Unspecified GSS failure.  Minor code may provide more information
Credentials cache file '/tmp/krb5cc_501' not found

debug1: Unspecified GSS failure.  Minor code may provide more information

debug1: Unspecified GSS failure.  Minor code may provide more information

debug1: Next authentication method: publickey
debug1: Offering public key: /home/feng/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Offering public key: .ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /home/feng/.ssh/identity
debug1: Trying private key: /home/feng/.ssh/id_dsa
debug1: Next authentication method: password
feng@myremote.host.net's password:

了解关于ssh免密码登录，强烈推荐这篇文章，基于ssh密钥对的自动登录原理及实际操作

另请参看 ssh无密码登入设置(完全版)/linux下免输入密码ssh登录

配置ssh不需要密码登录远程主机，网上有很多文章，但好像完整的不多，笔者参照操作，但得到消息：

Agent admitted failure to sign using the key.

原来是没有启动ssh-agent及把私钥加入到ssh-agent，参考如下文章得以解决问题。下文是完整的配置无密码登录ssh远程主机的方法，推荐参阅。

[注]正文来自http://www.jiangmiao.org/blog/559.html，在此表示感谢！

现有2台机器

1、服务器192.168.1.112

2、个人机192.168.1.110

要使110无需密码通过ssh登入112

步骤

1、创建密钥

miao@u32-192-168-1-110:~/.ssh$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase): (忽略)
Enter same passphrase again: (忽略)
Your identification has been saved in /home/miao/.ssh/id_rsa.
Your public key has been saved in /home/miao/.ssh/id_rsa.pub.

2、复制公密到服务器

miao@u32-192-168-1-110:~/.ssh$ scp id_rsa.pub miao@192.168.1.112:/home/miao/.ssh/192.168.1.110
miao@192.168.1.112's password:
id_rsa.pub                                                                   100%  404     0.4KB/s   00:00
miao@u32-192-168-1-110:~/.ssh$

3、添加公密到192.168.112的信任区域

miao@debian-192-168-1-112:~/.ssh$ cat 192.168.1.110 >> authorized_keys
miao@debian-192-168-1-112:~/.ssh$

注： 2，3两步可由命令ssh-copy-id一步到位

miao@ubuntu-192-168-1-110:~/.ssh$ ssh-copy-id miao@192.168.1.112
Password:
Now try logging into the machine, with "ssh 'miao@192.168.1.112'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

4、启动ssh-agent

如果ssh 192.168.112返回 Agent admitted failure to sign using the key
ps -Af | grep agent查看有无ssh-agent有无运行，若没有

miao@u32-192-168-1-110:~/.ssh$ ssh-agent

5、添加id_rsa到ssh-agent

miao@u32-192-168-1-110:~/.ssh$ ssh-add id_rsa

6、完成

from http://www.jiangmiao.org/blog/559.html