By default Location Based Access is disabled. Navigate to Tools -> Administration and you will not find Location Based Access Tab:
To enable the location based access tab, set the profile option ‘ASE_ADMINISTER_LOCATION_BASED_ACCESS_CONTROL’ to Yes:
Once this is set, Location Based Access tab will start appearing in the Tools -> Administration:
Click Enable Location Based access checkbox to enable the Location Based access:
Make sure atleast one valid IP address is entered otherwise the application will become inaccessible.
Also, please make sure that you make IT Security Manager Role Public.
By default you can enter only 10000 characters. If you want to extend this limit, please set the following profile option to Yes at site level: