如何使用公钥ssh认证

Question

我有 2 个 ubuntu 12.04（测试版）服务器（node1 和 node2），并且想在它们之间建立无密码的 root 访问。其他用户不应访问其他框。另请注意，ssh 默认端口更改为 220。

这是我所做的：

sudo -i
cd /root/.ssh
ssh-keygen -t rsa # with default name and empty password
cat id_rsa.pub > authorized_keys

然后将 id_rsa & id_rsa.pub 复制到 node2 并将 id_rsa.pub 添加到authorized_keys。两台主机都有相同的 /root/.ssh/config 文件：

Host node1
Hostname 1.2.3.4
Port 220
IdentityFile /root/.ssh/id_rsa

Host node2
Hostname 5.6.7.8
Port 220
IdentityFile /root/.ssh/id_rsa

现在的问题是，当我输入时，ssh node2它会要求我输入密码。可能是什么问题？

更新：

客户端调试信息：

debug1: Server host key: RSA ***
debug1: Host '[*.*.*.*]:220' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:6
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: /root/.ssh/id_rsa ((nil))
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/id_rsa
debug1: read PEM private key done: type RSA
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password
debug2: we did not send a packet, disable method
debug1: Next authentication method: password

服务器上的调试信息：

debug1: userauth-request for user root service ssh-connection method none [preauth]
debug1: attempt 0 failures 0 [preauth]
debug1: PAM: initializing for "root"
debug1: PAM: setting PAM_RHOST to "*.*.*.*"
debug1: PAM: setting PAM_TTY to "ssh"
debug1: userauth-request for user root service ssh-connection method publickey [preauth]
debug1: attempt 1 failures 0 [preauth]
debug1: test whether pkalg/pkblob are acceptable [preauth]
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: temporarily_use_uid: 0/0 (e=0/0)
debug1: trying public key file /root/.ssh/authorized_keys
debug1: fd 4 clearing O_NONBLOCK
debug1: matching key found: file /root/.ssh/authorized_keys, line 2
Found matching RSA key: ****
debug1: restore_uid: 0/0
debug3: mm_answer_keyallowed: key 0x7f0647b0c1b0 is allowed
debug3: mm_request_send entering: type 22
debug2: userauth_pubkey: authenticated 0 pkalg ssh-rsa [preauth]
Postponed publickey for root from *.*.*.* port 38887 ssh2 [preauth]

权限：

drwx------ 2 root root   4096 Mar 26 15:34 .ssh

-rw------- 1 root root  840 Mar 26 14:50 authorized_keys
-rw-r--r-- 1 root root  225 Mar 26 15:34 config
-rw------- 1 root root 1679 Mar 26 14:47 id_rsa
-rw-r--r-- 1 root root 2652 Mar 26 14:39 known_hosts

配置文件中的一些行：

PermitRootLogin without-password
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile  %h/.ssh/authorized_keys
UsePAM no # also tried yes

Answer 1

一些建议：

• 检查 /root/.ssh 的权限（及其内容
• 检查 ssh 是否允许 root 登录和/或公钥身份验证 (/etc/ssh/sshd_config iirc)
• 使用 ssh -v -v 查看更多调试输出