what finish to put on shiny finished old pine table top

[alilou]

I just purchased a very old knotty pine harvest table from a flea market. It has a very shiny finish now & I don't know what kind of finish this is. I'd like to do a little sanding & apply a new finish. Since it is a table top I'd like to use polyurethane but I'm concerned about the shiny top that it now has. I really don't want to completely strip the current finish. I'd appreciate any suggestions. I've done very little furniture refinishing