Testing of communication protocols and applications using simulated networks is necessary. In this paper, we show the development of a network emulator called as .Lenet.. Since our objective is to provide a network emulator as a user can use it more convenient, Lenet is developed as a userland application which is typically used by end users. Even though a userland application, Lenet has similar functions and accuracy to the existing software emulators of an in-kernel implementation type. Lenet gives two kinds of emulation. One is by parameters to simulate specific network conditions for an end-to-end. Another type of emulation is to replay the behavior of a real network using a replay scenario created by packet capture or written by a user. We present some evaluation results of Lenet on performance and convenience.