Are international students who live in the US allowed to make money on ebay?

I’m an international student in the US, been there for three years. I was thinking why not make some cash while my stay in the US. I know for sure that working in the US without a permit is illegal. But I’m not quiet certain if making deal online such as ebay is legal. Any other ideas on how to make money other than ebay are appreciated .

Thank you. Please no stupid answers. Best answer will be given five stars.