Wow, so this article was impetus enough for me to get key-based SSH working correctly on my Synology.

Of curiousity, I looked in my Synology's GUI for the logs, and find you can export them to CSV (System Logs > Connections).

I have _a lot_ of this sort:

    Warning,Connection,2014/08/03 21:10:17,SYSTEM,User [root] from [111.74.239.52] failed to log in via [SSH] due to authorization failure.

Curious how many distinct IPs, cut/grep/sed/sort:

  cut -d ' ' -f 5 ~/Downloads/connection.csv  | grep -E '[0-9.]+' | sed 's/\[//' | sed 's/\]//' | sort -u | wc

There are 143 distinct IPs, in the 111.x.y.z, 202, 210, 222, etc. ranges:

  ...  cut -d '.' -f -2 | sort -u
  111.74
  115.230
  115.239
  ...
  220.177
  222.186
  222.187

I punched a few into (http://www.whereisip.net/index.php) and they're mostly in China (except a 23.9... in Rochester, NY). All the successful log-ins are from myself, at least ( grep 'logged in' ...).