Logwatch出現pam(sshd)error - Linux

pam_succeed_if(sshd:auth): error retrieving information about user chaya : 1
time(s)
pam_succeed_if(sshd:auth): error retrieving information about user carlota :
1 time(s)
pam_succeed_if(sshd:auth): error retrieving information about user charisse
: 1 time(s)

每天Linux的Log都會出現這種訊息
我在iptables的rule該怎麼寫
才不會出現這些不該有的攻擊？

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