There have been many times setting up a tent where it is not possible to secure it via pegs for several reasons, for example camping on rock or in sand. There are also other reasons, wanting additional security even when using tent pegs, for example in high winds. Below are some photos that demonstrate a way to do that.
Here is a tent setup on a island that effectively is rock. Click on the thumbnails below to see a bigger photo.
Rocks secure the tent without pegs. Below shows the rocks at the corners.
How that works is to have some rope tied to the corner. Take the rope and loop it around a smaller rock.
Place a larger rock on the rope between the tent and the smaller rock.
In this case, these rocks provide additional security to tent pegs.
Can this be used in sand? Sure, tent pegs don’t work at all in sand. See in the photo below the tent is on a sand beach with rocks at the tent corners.
So how does it work? In the first two photos wind were around 20 knots. In the tent on the grass, winds reached over 50 knots. The tent on the beach had wind gusts reached to 20-25 knots. In all cases, the tent stayed put.