@Luciano-S. :thumbsup_tone2: Thank you! It works well.
$ uci export dropbear
$ uci set dropbear.@dropbear[0].PasswordAuth=0
$ uci set dropbear.@dropbear[0].RootPasswordAuth=0
$ uci commit dropbear
$ uci export dropbear
$ cat /etc/config/dropbear
$ /etc/init.d/dropbear restart
Ref:
https://community.onion.io/topic/1600/how-to-configure-dropbear-for-key-based-auth-only/3
https://wiki.openwrt.org/doc/howto/dropbear.public-key.auth
https://wiki.openwrt.org/doc/uci/dropbear