問題描述：
上週給公司搭建大數據平臺，選取三臺機器，安裝配置一切順利。後來發現/home目錄的掛載盤容量不夠用，所以就擴容了，在擴容之前將/home/hadoop文件夾複製到其他地方，擴容後再複製回來，現在問題來了，hadoop文件夾遷移回來後，發現免匙SSH無用了。
問題排查：
1.檢測權限
2.debug SSH
通過命令 ssh -vvv master 查看日誌
OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to master [127.0.0.1] port 22.
debug1: Connection established.
debug1: identity file /home/hadoop/.ssh/identity type -1
debug1: identity file /home/hadoop/.ssh/identity-cert type -1
debug3: Not a RSA1 key file /home/hadoop/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /home/hadoop/.ssh/id_rsa type 1
debug1: identity file /home/hadoop/.ssh/id_rsa-cert type -1
debug1: identity file /home/hadoop/.ssh/id_dsa type -1
debug1: identity file /home/hadoop/.ssh/id_dsa-cert type -1
debug1: identity file /home/hadoop/.ssh/id_ecdsa type -1
debug1: identity file /home/hadoop/.ssh/id_ecdsa-cert 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
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
debug3: Wrote 960 bytes for a total of 981
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_setup: found hmac-md5
debug1: kex: server->client aes128-ctr hmac-md5 none
debug2: mac_setup: found hmac-md5
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
debug3: Wrote 24 bytes for a total of 1005
debug2: dh_gen_key: priv key bits set: 114/256
debug2: bits set: 512/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: Wrote 144 bytes for a total of 1149
debug3: check_host_in_hostfile: host master filename /home/hadoop/.ssh/known_hosts
debug3: check_host_in_hostfile: host master filename /home/hadoop/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 5
debug1: Host 'master' is known and matches the RSA host key.
debug1: Found key in /home/hadoop/.ssh/known_hosts:5
debug2: bits set: 525/1024
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
debug3: Wrote 16 bytes for a total of 1165
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug3: Wrote 48 bytes for a total of 1213
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/hadoop/.ssh/identity ((nil))
debug2: key: /home/hadoop/.ssh/id_rsa (0x2ae9888a6330)
debug2: key: /home/hadoop/.ssh/id_dsa ((nil))
debug2: key: /home/hadoop/.ssh/id_ecdsa ((nil))
debug3: Wrote 64 bytes for a total of 1277
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic,password
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup gssapi-keyex
debug3: remaining preferred: gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_is_enabled gssapi-keyex
debug1: Next authentication method: gssapi-keyex
debug1: No valid Key exchange context
debug2: we did not send a packet, disable method
debug3: authmethod_lookup gssapi-with-mic
debug3: remaining preferred: publickey,keyboard-interactive,password
debug3: authmethod_is_enabled gssapi-with-mic
debug1: Next authentication method: gssapi-with-mic
debug3: Trying to reverse map address 127.0.0.1.
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
Credentials cache file '/tmp/krb5cc_501' not found
debug2: we did not send a packet, disable method
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/hadoop/.ssh/identity
debug3: no such identity: /home/hadoop/.ssh/identity
debug1: Offering public key: /home/hadoop/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug3: Wrote 368 bytes for a total of 1645
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /home/hadoop/.ssh/id_dsa
debug3: no such identity: /home/hadoop/.ssh/id_dsa
debug1: Trying private key: /home/hadoop/.ssh/id_ecdsa
debug3: no such identity: /home/hadoop/.ssh/id_ecdsa
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: password3.從日誌信息並沒有看到是權限問題，通過比較可以正常免匙的機器發現以下不同：
在這期間我嘗試新建了用戶test，在新建的用戶中配置免匙ssh依然不行，但是發現root用戶的免匙SSH是ok的，現在目標又回到了權限問題，可是發現權限都是ok的。
4.在快要放棄的時候搜到了這篇帖子：http://www.linuxidc.com/Linux/2013-07/87267.htm
看了這篇文章後我立刻用ls -laZ檢查了我的.ssh目錄：
[hadoop@master ~]$ ls -laZ .ssh
drwx------. hadoop hadoop unconfined_u:object_r:file_t:s0 .
drwxr-xr-x. hadoop hadoop unconfined_u:object_r:file_t:s0 ..
-rw-------. hadoop hadoop unconfined_u:object_r:file_t:s0 authorized_keys
-rw-------. hadoop hadoop unconfined_u:object_r:file_t:s0 id_rsa
-rw-r--r--. hadoop hadoop unconfined_u:object_r:file_t:s0 id_rsa.pub
-rw-r--r--. hadoop hadoop unconfined_u:object_r:file_t:s0 id_rsa.pub.slave1
-rw-r--r--. hadoop hadoop unconfined_u:object_r:file_t:s0 id_rsa.pub.slave2
-rw-r--r--. hadoop hadoop unconfined_u:object_r:file_t:s0 known_hosts
我也是“果然不是ssh_home_t”。
5.解決問題：
切換到root用戶，修復context:
[root@master ~]# restorecon -r -vv /home/
[hadoop@master ~]$ ls -laZ .ssh
drwx------. hadoop hadoop unconfined_u:object_r:ssh_home_t:s0 .
drwxr-xr-x. hadoop hadoop unconfined_u:object_r:user_home_dir_t:s0..
-rw-------. hadoop hadoop unconfined_u:object_r:ssh_home_t:s0 authorized_keys
-rw-------. hadoop hadoop unconfined_u:object_r:ssh_home_t:s0 id_rsa
-rw-r--r--. hadoop hadoop unconfined_u:object_r:ssh_home_t:s0 id_rsa.pub
-rw-r--r--. hadoop hadoop unconfined_u:object_r:ssh_home_t:s0 id_rsa.pub.slave1
-rw-r--r--. hadoop hadoop unconfined_u:object_r:ssh_home_t:s0 id_rsa.pub.slave2
-rw-r--r--. hadoop hadoop unconfined_u:object_r:ssh_home_t:s0 known_hosts
6.驗證是否解決：
[hadoop@master ~]$ ssh master
Last login: Wed May 31 09:01:48 2017 from 10.0.17.19
Starting Nexus OSS...
Started Nexus OSS.
-bash: /etc/profile.d/mystart.sh: line 2: syntax error near unexpected token `&&'
-bash: /etc/profile.d/mystart.sh: line 2: ` && '
[hadoop@master ~]$
7.問題總結：
根本原因是我將/home/hadoop目錄做了移動，可是移動回來的時候用的是root用戶，即便我改回了hadoop:hadoop，可是目錄下的文件夾的context變了，而ssh鑑權又非常嚴格必須是ssh_home_t纔可以。