Question : Problem: GRE over IPSEC Configuration for two remote offices

How do I configure a GRE tunnel to link two remote offices together while sending the traffic using a  IPSEC to provide the maximum security and encryption for  the traffic being passed over the internet.    I am proposing to use routers on both sides which have been configured with public addresses on their outside interfaces and diverse private networks on their inside interfaces. Router A has a 10.1.x.x set of networks behind it, Router B has a set of 135.209.x.x set of networks behind it.

Answer : Problem: GRE over IPSEC Configuration for two remote offices

 If you feel the need for using GRE, then the following link will give you some examples, look for "router-to-router" or "GRE" in the web page:
 http://www.cisco.com/en/US/tech/tk583/tk372/tech_configuration_examples_list.html

  Personally, I prefer a plain old site-to-site IPSec VPN between routers - works great.  Something like the following (an example from the same URL above):
  http://www.cisco.com/en/US/tech/tk583/tk372/technologies_configuration_example09186a008009448f.shtml

HTH