Metallic wire meshes are used worldwide for rockfall protective systems, such as rockfall net barriers and drapery meshes. Within different types of meshes, the doubletwisted hexagonal mesh is commonly used. This paper focuses on the implementation and validation of a computational tool for the simulation of the behaviour of such meshes as a single part and as a component of a rockfall protective system. The discrete element method (DEM) is used to model the rockfall mesh and the impacting blocks. The opensource framework YADE has been extended in this context. Tensile tests of a plane net sheet subjected to a constant strain rate are used to calibrate the numerical model. Finally, the simulation of an impacting block on a horizontally spanned net is investigated where numerical results are compared to experimental results.