What was the public's general consensus on internment in Australia during and leading up to WW2?

Civilian internment in Australia was enabled by the National Security Act (1939). From the National Archives of Australia webpage on wartime internment:

"During World War II, Australian authorities established internment camps for three reasons – to prevent residents from assisting Australia's enemies, to appease public opinion and to house overseas internees sent to Australia for the duration of the war."

Fears of a Fifth Column movement was of concern to Australians at the time. There were sizable and established (read: almost 100 years) migrant populations - such as the Germans of South Australia and Italians of North Queensland - that still retained links to the homeland. Local propaganda reflected/exacerbated the approval of internment.

Australia interned about 7000 residents, including nationals from over 30 other countries, such as Finland, Hungary, Portugal and Russia. As a percentage of the major Axis resident populations, 15% of Italians, 33% of Germans and almost 100% of Japanese were interred.

A further 8000 people were sent to Australia to be interned from Britain, Palestine, Iran, Malaya, New Zealand and New Caledonia. The most infamous group to be sent to Australia was the Germans and Italians prisoners on the Dunera in 1940. Here is an article from the BBC about the "The Dunera Boys"