Zoom has been used by high schools, yoga classes, and blue chip companies as a video conferencing platform during coronavirus-related home stays. The free version allows up to 100 participants to join a meeting, and more participants can be paid for.

However, Zoom also has a dark side: anyone who knows how to set up a Zoom meeting or join a Zoom meeting can join a meeting by default, as long as they know the meeting link. As a result, trolls "Zoom bomb" meetings, shocking other participants with pornography and causing mayhem.

Earlier this month, prominent technology journalists Kara Swisher and Jessica Lessin hosted a public Zoom meeting to discuss the obstacles faced by female tech entrepreneurs, The New York Times reported.

"They were forced to abruptly end the event after only 15 minutes of conversation when a participant began broadcasting a shocking video called '2 Girls 1 Cup,'" the Times reported.

An open Zoom meeting attended daily by tech journalists and investors was also hit by what appeared to be the same Zoom bomber, TechCrunch reported. The Times spoke to one person who said her online book club's Zoom meeting ended after 30 minutes because someone started posting pornography.

Blocking the vandal does not stop the porn bombs.

Now Zoom has come to the rescue with a blog post titled "How to Keep the Party Crashers from Crashing Your Zoom Event."

"Sharing meeting links on social media and other public forums makes the event very public. Anyone with the link can attend your meeting."

So here are some things you can do if you are the organizer of a Zoom meeting.

Click the arrow next to "Share Screen" in the Host Controls at the bottom of the Zoom screen, select "Advanced Sharing Options" and make sure the "Who can share" option is set to "Hosts only."

This allows all participants to enter the waiting area before the meeting begins and approve one by one or all at once. This can be enabled in Account Management > Account Settings > Meetings > Waiting Room. For more information on waiting rooms, see Zoom.

This is tougher on latecomers, but prevents some people from showing up at the door. Click on "Manage Participants" at the bottom of the host screen and select "Lock Meeting.

This will stop jerks from using the text chat feature during the meeting to upload pornography. Select "Account Management" > "Account Settings" > "Meetings" > "File Transfer.

More tips can be found in a post on the Zoom blog. A few of them are exclusive to paid Zoom accounts, such as making meetings invitation-only and requiring attendees to log in with a password.