Stalking, cyber-bullying and child grooming are all ongoing threats to internet users, with young children particularly vulnerable.

Associate Professor of Charles Sturt University's School of Psychology Gene Hodgins said the impact of online threats could be severe, but reminded parents of the role they played in alleviating the risks.

"Depending on the extent of issues like bullying, a child may start to feel things like guilt, they might think it's their fault or that they've contributed to the bullying in some way, or they may feel hopeless, and all of those things can lead to lowered moods, depression, not wanting to go to school or socially withdrawing themselves," Dr Hodgins said.

"If a parent starts to notice those signs in their child, the best thing to do is to approach them openly, ask them if they're feeling OK or mention, say, you've noticed them spending a lot of time in their rooms."

The prompt for online safety follows a warning released by the Australian Federal Police for parents to check their online privacy settings before posting pictures of their children on social media.

AFP Commander of the Australian Centre to Counter Child Exploitation and Child Protection Operations Hilda Sirec said the back-to-school period was a timely reminder to implement safe online practices.

If a child is withdrawing from social settings, seeming down or using social media frequently, start an open conversation.

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"We are urging parents and carers who are sharing those images to make sure they're using secure privacy settings and only sharing images with people they know and trust," she said.

"Some [child assault] offenders go to great lengths in order to gain access to children and the AFP is seeing instances of online grooming starting from the information that parents and carers are sharing online."

According to eSafety Commissioner Julie Inman Grant, parents should approach privacy with common sense.

"While the risks are real, it's important for parents not to panic, there are simple things you can do to limit the risk including only sharing content with people you know and trust [and changing settings to] 'friends only' on Facebook, for instance," she said. "Since school is also about learning, this is also a good opportunity to talk to your child about privacy, safety and consent."

Report online child exploitation via www.accce.gov.au/report. For children's mental health support, call the Kids Helpline on 1800 551 800, or Beyond Blue on 1300 224 636.