Question

Explain about security that can be provided in these three layers: Application layer, TCP/IP layer, network layer.

Answer 1

Layer	Security Protocol
Application Layer	PGP. S/MIME, HTTPS
Transport Layer	SSL, TLS, SSH
Network Layer	IPSec

Security at Application Layer

end-to-end security is provided at a user level by encryption applications at sender side and decryption at receiver side.

That is, Cryptography is done for security in application layer.

Security at TCP/IP layer

It includes Application layer, Transport layer, network layer and data-link layer.

Now coming to

Transport layer: Using Transport layer protocols HTTP traffic is secured and done by Transport Layer Security (TLS) protocol.

Data Link Layer : Generally provides link-to-link security, link layer encryption .  It typically begins with encrypting plain text on a host serve as it leaves the host, and decrypted when it reaches the next link.

rest has been discussed

Security at Network Layer

IPSec: It provides data authentication, integrity, and confidentiality.It manages encryption, decryption and authentication of packets. It encrypts the application layer data and provides security for routers.