In some examples, a modular server includes an auxiliary power source and an auxiliary power system. The auxiliary power system includes a battery terminal to electrically couple to the auxiliary power source. The auxiliary power system further includes power terminals. Each power terminal is electrically coupled to a respective resource received within a modular server enclosure. The auxiliary power system further includes a power circuitry electrically coupled to the battery terminal and to each of the power terminals. The auxiliary power system also includes security circuitries. Each security circuitry corresponds to a respective resource received within a modular server enclosure. The auxiliary power source supplies power to the plurality of security circuitries.