If you do not plan to change settings on your ubiquiti router remotely it is a recommended security measure to disable SSH and graphical interface (GUI) access from the Internet. By default anyone that knows your public IP can try to log-in using the GUI or SSH.
The commands to disable the above as as follows:
configure
set service gui listen-address 192.168.0.1
set service ssh listen-address 192.168.0.1
commit
save
exit
(192.168.0.1 is the default gateway, if you LAN gateway is not 192.168.0.1, you should change the IP to match your LAN gateway IP).
It is also possible to disable SSH completely from the GUI. Click on system tab and un-check ssh access. This will block SSH completely wont work even from your LAN, , only the GUI will remain accessible.