At least in my version of dropbear (v2015.67), the message logged for a bad password attempt starts with a capital B, and therefore is not caught by "egrep 'login attempt for nonexistent user' ..." in the lines 90 and 91:
Mon Sep 24 15:25:27 2018 authpriv.warn dropbear[2177]: Bad password attempt for 'root' from 192.168.1.19:45424
I would suggest to add a "-i" option after "egrep".
At least in my version of dropbear (v2015.67), the message logged for a bad password attempt starts with a capital B, and therefore is not caught by "
egrep 'login attempt for nonexistent user' ...
" in the lines 90 and 91:Mon Sep 24 15:25:27 2018 authpriv.warn dropbear[2177]: Bad password attempt for 'root' from 192.168.1.19:45424
I would suggest to add a "-i" option after "egrep".