What kind of security measures are used in different layers of TCP/IP? Explain.

Question

What will be an ideal response?

Answer 1

The TCP/IP protocol stack has in built security mechanisms at the various levels.
These are as follows:
TCP: The TCP suite uses the SSL/TLS security suite. This protocol is
summarized as follows:
Secure Socket Layer/Transport Layer Security (SSL/TLS): The SSL/TLS protocol
divides the data into records. These records are of four types: user data,
handshake messages, alerts and change cipher specs. User A first contacts user B
to initiate dialogue. B sends his certificate to A. After verifying the certificate, A
extracts B.s public key. It then picks a random number R, encrypts it with B.s
public key and sends it to B. Both now compute the session key using this random
number.
IP: The IP layer uses the IP Security protocol (IPSec) for security purposes. This
protocol, coupled with the Internet Key Exchange (IKE) protocol, makes the IP
layer security quite robust. A Security Association (SA) is established between
the two end parties. The IKE protocol uses a Diffie Hellman key exchange
process to ensure integrity of the messages passed.
The security is additionally protected by an optional certificate that either party
may request from each other. Having established a shared session key using IKE, the IPSec protocol comes into play. The IPSec protocol has two components, the
Authentication Header (AH) and the Encapsulating Security Payload (ESP). AH
provides integrity protection only while ESP provides encryption and/or integrity
protection. In most cases, only one of the two is used.
IPSec operates in two modes, the tunnel and the transport mode. In the tunnel
mode, the original IP packet is kept intact and a new IP header is added to the
packet. The transport mode adds the IPSec information between the IP header and
the remainder of the packet.