IPsec & Encryption

This post is in relation to a question asked by reader

Question:

Angus has left a new comment on your post "IP Security & Authentication Header (AH)":

May I ask a question about IPsec?
Which of the following VPN methods will transmit data across the local network in plain text without encryption?

A. Secure Sockets Layer (SSL)
B. IPsec
C. Transport Layer Security (TLS)
D. Layer 2 Tunneling Protocol (L2TP)
The book answer is B, but why? IPsec does provide the encryption, dosen't it?


Answer:

You are perfectly right IPSec do provide Encryption.


Let us see each choice one by one:

A. Secure Sockets Layer (SSL)

SSL is the predecessor of Transport Layer Security (TLS).SSL encrypts data of OSI Layer -4 and provide end to end connectivity


B. IPSec

IPSec helps in
i. Authentication
ii. Encryption

Encryption is decided by Security Association (SA)



C. Transport Layer Security (TLS)

TLS also encrypts data of OSI Layer -4 and provide end to end connectivity and is actualyy successor of SSL.



D.Layer 2 Tunneling Protocol (L2TP)

L2TP is essentially a Layer 5 Protocol.It does not provide encryption by itself. With the help of IPSec encryption is provided for data transfer.




So, in my view, the corect answer should be D. Layer 2 Tunneling Protocol (L2TP) and not the B. IPsec.

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