Towards an optical synthesis of low phase noise continuous millimeter waves in a compact and an all-fiber system, we present the all-electrical locking of the optical frequency of a distributed feedback laser (DFB) diode at 1549 nm tunable over 2 nm, on a fibered Fabry-Perot (FP) cavity. We demonstrate a 6 MHz servo bandwidth and a frequency noise suppression down to 3.10^-1 Hz/√Hz at 80 kHz carrier offset frequency in the error signal. Furthermore, we use a Brillouin fiber laser in order to refine the stabilized laser linewidth and we then demonstrate a frequency noise suppression down to 4 Hz/√Hz at 1 MHz offset frequency, limited by the phase noise floor of the measurement instrument.