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https://velog.io/@gclee/CentOS-7-OpenSSH-%EC%84%A4%EC%B9%98-%EB%B0%8F-%EC%84%B8%ED%8C%85
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https://library.gabia.com/contents/infrahosting/9008/
centos – Issue with world readable sudoers file – Unix & Linux Stack Exchange
https://unix.stackexchange.com/questions/674000/issue-with-world-readable-sudoers-file