  In this paper, we have considered flat
Friedmann-Lema\^{i}tre-Robertson-Walker metric in the framework of perfect
fluid models and modified $f(G)$ gravity (where $G$ is the Gauss Bonnet
invariant). Particularly, we have considered particular realistic $f(G)$
configurations that could be used to cure finite-time future singularities
arising in the late-time cosmic accelerating epochs. We have then developed the
viability bounds of these models induced by weak and null energy conditions, by
using the recent estimated numerical figures of the deceleration, Hubble, snap
and jerk parameters.
