Report: Moyes linked with another defender reunion
Duffy is under contract with Brighton until 2023 but he was a frustrated figure at times last season, starting just 12 Premier League games and has not been a regular in the first XI this season following the arrival of Adam Webster.
The recent signing of Dutch defender Joel Veltman will add extra to the competition for places. Brighton have not formally put Duffy up for sale but they have suggested that some players will be available on loan for next season.
David Moyes was Everton manager when Duffy made his debut for the Toffees as a 17-year-old and the pair have a good working relationship.
Duffy could be available on loan or a cut-price permanent fee this summer and with Fabian Balbuena, a potential departure and no way back for Winston Reid, Duffy could find himself a target for centre back cover next season.