IPSec Flashcards
What are the two methods used in IPSec?
Authentication Header and Encapsulating Security Payload
What two services are provided by IPSec?
Transport and Tunnel mode
How do AHs achieve authentication (sender side) ?
- Apply hash to plaintext to create message digest
- Append message digest to plaintext
How do AHs achieve authentication (receiver side) ?
- Apply hash to plaintext
- Compare between message digest and hashed plaintext
What is the IP header format for AH in IPv4 for transport mode?
Original IP Header, AH, TCP, Data
What do the security parameters index do?
Allows sender and receiver to know what protocols are used
What does the sequence number in an ESP header prevent?
Replay attacks
What 4 fields can be encrypted in the ESP header?
Payload, padding, pad length, next header
What policy choices exist in IPSec?
Discard packet, protect packet with AH and ESP security protocols, let packet bypass IPSec processing
A security association is defined by 3 parameters, what are they?
Security Parameters Index, IP destination address, Security Protocol Identifier: AH or ESP
What defines IPSec transport mode?
It only encrypts the data being sent without setting up a secure connection. This can be inferred from not having a new IP header.
What defines IPSec tunnel mode
Tunnel mode sets up a secure connection and also encrypts the data being sent. This can be inferred from having a new IP header.
