The steering gear leaks at the input shaft.
This is common in older vehicles. The input shaft has a seal and bushing that get worn over time. The typical repair is to replace the steering gear. If you vehicle is equipped with air bags, special precautions and procedures will need to be followed to not damage the air bag components. A qualified mechanic can properly assess and make the right repairs to fix the leak. They can also check any other steering components that may be worn, like the pitman arm, as this might be a good time to replace them as well.