systemctl status sshd
● sshd.service - OpenSSH server daemon
Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2019-03-05 16:04:47 CST; 48min ago
Docs: man:sshd(8)
man:sshd_config(5)
Main PID: 5490 (sshd)
CGroup: /system.slice/sshd.service
└─5490 /usr/sbin/sshd -D
Mar 05 16:29:45 server10-20 sshd[6943]: Accepted password for root from 172.16.2.47 port 45637 ssh2
Mar 05 16:36:22 server10-20 sshd[7282]: PAM unable to dlopen(/lib/security/pam_limits.so): /lib/security/pam_limits.so: wrong ELF class: ELFCLASS32
Mar 05 16:36:22 server10-20 sshd[7282]: PAM adding faulty module: /lib/security/pam_limits.so
Mar 05 16:36:24 server10-20 sshd[7282]: Accepted password for root from 172.16.2.47 port 36622 ssh2
Mar 05 16:50:13 server10-20 sshd[8403]: PAM unable to dlopen(/lib/security/pam_limits.so): /lib/security/pam_limits.so: wrong ELF class: ELFCLASS32
Mar 05 16:50:13 server10-20 sshd[8403]: PAM adding faulty module: /lib/security/pam_limits.so
解决方法：
mkdir /lib/security/
cp /lib64/security/pam_limits.so /lib/security/
用一个例子来演示会更加清晰
