Thank you to all for the responses. Since this could eventually become a more 
serious issue some additional analysis on the log was completed identifying 21 
distinct originating IP addresses from the countries listed below. UFW rules 
were added to block these IP addresses and the authentication failures have 
stopped.

Korea (the Republic of) [KR] 
China [CN] 
United States of America [US] 
India [IN] 
Germany [DE] 
Cameroon [CM] 
Singapore [SG] 
Brazil [BR] 
Russian Federation [RU] 
Singapore [SG]
China [CN]

-Bryan
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