Former Real Madrid star and Spanish international Karanka had been working at the Santiago Bernabeu under Jose Mourinho.
Karanka did not follow Mourinho to Chelsea in the summer, and once Carlo Ancelotti arrived, he parted company with the club despite having some three years left on his deal.
Now it is understood Karanka is showing an interest in taking on a managerial role, and it is believed he has expressed an interest in both the Middlesbrough and Crystal Palace vacancies.
Indeed, Karanka is currently the bookmakers favourite for the Boro job, and his agents have confirmed an interest from a number of clubs.
"Some clubs have asked about the situation of Karanka and we are managing some options but there are no agreements," a spokesman for Gestifute, run by leading agent Jorge Mendes, told Sky Sports.
As well as England, Karanka is reported to be attracting interest from France and the Middle East.