分類： LINUX
環境： centos6a,centos6b,centos6c
需求：從centos6a免密碼，自動登陸到centos6b或者centos6c
步驟：
1 修改每臺機器的/etc/hosts文件，內容如下
127.0.0.1 localhost
192.168.0.2 centos6a
192.168.0.3 centos6b
192.168.0.4 centos6c
2 本機創建ssh密鑰
centos6a#: ssh-keygen -t rsa -P '' -f
~/.ssh/id_dsa
-P表示密碼，-P '' 就表示空密碼，也可以不用-P參數，這樣就要三車回車，用-P就一次回車。
3 拷貝密鑰到“被登陸機”輸入密碼，
centos6a#:~/.ssh#scp id_rsa.pub centos6b:~/.ssh/
centos6a#:~/.ssh#scp id_rsa.pub centos6c:~/.ssh/
4 ssh到“被登陸機”(centos6b,centos6c)把密鑰改成 “authorized_keys”
centos6b#:~/.ssh# mv id_rsa.pub authorized_keys
centos6c#:~/.ssh# mv id_rsa.pub authorized_keys
5 在“被登陸機”(centos6b,centos6c)上執行命令 restorecon
說明：There is a bug in CentOS 6 / SELinux that results in all client presented certificates to be ignored when SELinux is set to Enforcing. To fix this simply:
centos6b#:restorecon -R -v ~/.ssh
centos6c#:restorecon -R -v ~/.ssh
或者
centos6b#: setenforce 0
centos6c#: setenforce 0
6 ssh centos6b 這樣就實現無密碼登陸
