Set LogLevel as DEBUG

1) Take a backup of /etc/ssh/sshd_config
cp -p /etc/ssh/sshd_config /etc/ssh/sshd_config.bkp_$(date +%F)

2) Update LogLevel
sed -i ‘s/^LogLevel.*/LogLevel DEBUG/’ /etc/ssh/sshd_config

3) Verify change
grep LogLevel /etc/ssh/sshd_config
systemctl restart sshd
systemctl status sshd