You can use either term. Near usually refers to close to and by can refer to being close to or next to an object.

Yo pensaría la diferencia es como "por" y "cerca", no? Por ejemplo: The bathroom is near the kitchen. El baño está cerca de la cocina. (es que, no hay mucha distancia entre los dos) The bathroom is back there, in the back of the house. El baño está por allá, al fondo de la casa. (no es tan preciso) Ojala yo entienda "cerca" y "por" ;)

By can be used to mean the same thing as near, but the word by also has other uses where near does not. Feel free to use either :)