How does IPsec provide secure networking for applications within an organization?

IPsec does not take advantage of FTP; FTP is an application-layer protocol for file transfer, and IPsec operates at the network layer to secure IP communications, independent of specific application protocols.

While IPsec can be used to secure GRE tunnels, GRE itself is a separate tunneling protocol, and IPsec provides the security mechanisms, not the GRE tunnels directly.

IPsec operates by establishing Security Associations (SAs) between communicating peers. Each SA is a simplex connection that defines the security parameters, including cryptographic algorithms, keys, and protocols (Authentication Header or Encapsulating Security Payload), necessary for secure communication, ensuring data confidentiality, integrity, and authenticity for applications.

IPsec does not leverage TFTP; TFTP is an insecure file transfer protocol that IPsec could protect, but it doesn't provide the security mechanisms itself.