  We study weak lensing properties of filaments that connect clusters of
galaxies through large cosmological $N$-body simulations. We select 4639 halo
pairs with masses higher than $10^{14}h^{-1}\mathrm{M}_\odot$ from the
simulations and investigate dark matter distributions between two haloes with
ray-tracing simulations. In order to classify filament candidates, we estimate
convergence profiles and perform profile fitting. We find that matter
distributions between haloes can be classified in a plane of fitting
parameters, which allow us to select straight filaments from the ray-tracing
simulations. We also investigate statistical properties of these filaments,
finding them to be consistent with previous studies. We find that $35\%$ of
halo pairs possess straight filaments, $4\%$ of which can directly be detected
at $S/N\geq2$ with weak lensing. Furthermore, we study statistical properties
of haloes at the edges of filaments. We find that haloes are preferentially
elongated along filamentary structures and are less massive with increasing
filament masses. However, the dependence of these halo properties on masses of
straight filaments is very weak.
