A vent plug for a milking liner has an inlet that faces the outer surface of the liner. The position of the vent inlet reduces the likelihood that it will become clogged with debris from the floor of the milking parlor. In one embodiment, the vent plug has a plurality of redundant inlets that allow the vent plug to function if one of the inlets becomes clogged. In another embodiment, the inlet is angled at a nonparallel angle with respect to the vent passage.