Hadoop SSH免密码登录以及失败解决方案

1. 创建ssh-key

这里我们采用rsa方式，使用如下命令：

xiaosi@xiaosi:~$ ssh-keygen -t rsa -f ~/.ssh/id_rsa
Generating public/private rsa key pair.
Created directory '/home/xiaosi/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/xiaosi/.ssh/id_rsa.
Your public key has been saved in /home/xiaosi/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:n/sFaAT94A/xxxxxxxxxxxxxxxxxxxxxxx xiaosi@xiaosi
The key's randomart image is:
+---[xxxxx]----+
|    o= .. .. |
|    o.= .. .|
|     *.* o .|
|    +.4.=E+..|
|    .SBo=. h+ |
|    ogo..oo. |
|     or +j..|
|     ...+o=.|
|     ... o=+|
+----[xxxxx]-----+

备注：

这里会提示输入pass phrase，一定不要输入任何字符，回车即可。

2. 生成authorized_keys文件

xiaosi@xiaosi:~$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

备注：

记得要把authorized_keys文件放到.ssh目录下，与rsa等文件放在一起，否则免登录失败，debug如下（ssh -vvv localhost进行调试，查找错误原因）：

xiaosi@xiaosi:~$ ssh -vvv localhost
OpenSSH_7.2p2 Ubuntu-4ubuntu1, OpenSSL 1.0.2g-fips 1 Mar 2016
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "localhost" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to localhost [127.0.0.1] port 22.
debug1: Connection established.
debug1: identity file /home/xiaosi/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /home/xiaosi/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/xiaosi/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/xiaosi/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/xiaosi/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/xiaosi/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/xiaosi/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/xiaosi/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu1
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu1 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to localhost:22 as 'xiaosi'
debug3: hostkeys_foreach: reading file "/home/xiaosi/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/xiaosi/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys from localhost
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected],aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected],aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug1: kex: algorithm: [email protected]
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: [email protected] MAC:  compression: none
debug1: kex: client->server cipher: [email protected] MAC:  compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:378enl3ckhdpObP8fnsHr1EXz4d1q2Jde+jUplkub/Y
debug3: hostkeys_foreach: reading file "/home/xiaosi/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/xiaosi/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys from localhost
debug1: Host 'localhost' is known and matches the ECDSA host key.
debug1: Found key in /home/xiaosi/.ssh/known_hosts:1
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS received
debug2: key: /home/xiaosi/.ssh/id_rsa (0x5602df5e80c0)
debug2: key: /home/xiaosi/.ssh/id_dsa ((nil))
debug2: key: /home/xiaosi/.ssh/id_ecdsa ((nil))
debug2: key: /home/xiaosi/.ssh/id_ed25519 ((nil))
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
debug3: preferred gssapi-keyex,gssapi-with-mic,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: Offering RSA public key: /home/xiaosi/.ssh/id_rsa
debug3: send_pubkey_test
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/xiaosi/.ssh/id_dsa
debug3: no such identity: /home/xiaosi/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/xiaosi/.ssh/id_ecdsa
debug3: no such identity: /home/xiaosi/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/xiaosi/.ssh/id_ed25519
debug3: no such identity: /home/xiaosi/.ssh/id_ed25519: No such file or directory
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
xiaosi@localhost's password: 

3. 验证

xiaosi@xiaosi:~$ ssh localhost
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:378enl3ckhdpObP8fnsHr1EXz4d1q2Jde+jUplkub/Y.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts.
sign_and_send_pubkey: signing failed: agent refused operation
xiaosi@localhost's password: 

4. authorized_keys权限

我们可以看到还是让我输入密码，很大可能是authorized_keys文件权限的问题，我们给该文件赋予一定权限：

xiaosi@xiaosi:~$ chmod 600 ~/.ssh/authorized_keys

再次验证：

xiaosi@xiaosi:~$ ssh localhost
Welcome to Ubuntu 16.04 LTS (GNU/Linux 4.4.0-24-generic x86_64)
 * Documentation: https://help.ubuntu.com/
0 个可升级软件包。
0 个安全更新。
Last login: Thu Jun 16 08:05:50 2016 from 127.0.0.1

到此表示OK了。

备注：

或者第一次需要输入密码，以后再次登陆就不需要输入密码了。

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