Where in the constitution does it provide the president with the power/authority to ban immigrants from certain countries?

Well the constitution only applies for naturalized citizens of the United States, so immigrants who arent citizens are not garaunteed the same rights, and thus whether it goes against the principals of the constitution, or is not explicitly written in there (which I am not reading through the entire constitution to find) is irrelevant. In other words, although the 14th Ammendments says, "no state shall make a law that abridges the privledges and immunities of citizens", it doesn't apply to everyone else. However, if we the people are against this, it is our right as citizens to fight back against this practice; with seperation of powers we can either write new laws in congress or judge the validity of the ban in the supreme court.