Yes, it is, but you also have to have the will to do it.
The Howard government introduced its policies to address this issue in 2001 - and illegal immigration by boat almost vanished. Those policies were in place until 2007 when a Labor government was elected and they abandoned those policies. And you can see the results of this in the graph.
Finally in July 2013, even the Labor government (facing an election only three months away) finally conceded their approach wasn't working, and reintroduced the same type of policies. This graph shows those results:
The Liberal/National government (conservative) elected in September 2013 has kept the policies in place, and the number is basically down to zero.
It is easier for Australia to secure its borders than most countries. But you still have to make the choice to do it.