Understanding IPSec: Authentication, Encryption, and Implementation, Slides of Applications of Computer Sciences

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After Seventh Semester Onwards…….

What is IPSec?

• IPSec stands for Internet Protocol Security
• It is at a most basic level a way of adding security

to your network traffic without having to modify

the applications that are using IP

Where is IPSec Used?

• Wireless nets

• Virtual Private Networks (VPNs)

• Non-trusted Local Area Networks (LANs)

IP Basics

• The IP protocol breaks down information

that is to be sent out into small manageable

pieces called packets

• Packets are reassembled at the receiving

side

Parts of the Header

• Source Address

• Destination Address

• Protocol

• Fragment Flag

• Total Length

• Type of Service

• And more…

Data Section

• This portion holds all of the data that you

are trying to transmit

What IPSec does.

• Authentication

• Encryption

• With Two Major modes

• Tunnel
• Transport
  • AH + ESP
  • AH
  • ESP

Authentication

• An Authentication Headers (AH) portion is added

to the IP Packet

• The AH contains fields
  • Next Header
  • AH payload length
  • Security Parameters Index (SPI)
  • Anti-Replay Sequence number
  • Authentication Data field (Information dependent on the cipher used)

Tunnel mode

IP Header

AH Header

SPI and Sequence Number

IP Header

Upper Protocol Headers and Packet Data

ESP Trailer

ESP Authentication Data

Note: Fields in Green are Encrypted

Transport mode

IP Header

AH Header

SPI and Sequence Number

Upper Protocol headers and Packet Data

ESP Trailer

ESP Authentication Data

Note: Fields in Green are Encrypted

Section II

Proposed Algorithm

1. Route Discovery by SAODV SAODV route Discovery: Source Destination [Shared key of both source and destination will be exchanged during this phase] 2. Establishment of SA Data_Message= ((Sequence Number Counter +AH Information/ESP Information) EKS- priv) EKD-pub: SourceDestination (With First UDP Packet) [AH information: authentication algorithm, shared secret key, key lifetime] [ESP information: encryption algorithm, shared secret key, key lifetime] 3.Data Transmission IF (AH implemented packet) Packet with AH header: Source to Destination and Destination to Source ELSE IF (ESP implemented packet) Packet with AH header: Source to Destination and Destination to Source 4. ACK_PKT IF (Check (Authentication)= = true)) Send ACK_PKT ELSE IF ((De encapsulate (Packet) & & check (Authentication)) = = true) Send ACK_PKT ELSE Drop PKT 5. Receive ACK_PKT IF sender Receive (ACK_PCK) = = true) Send next packet Else Retransmit same data packet 6. END

Create a Basic NS Simulation

1. Create event scheduler

2. Create nodes and links

3. Create connections

4. Create traffic sources/sinks

5. Enable tracing

TclClass

Static class TcpClass : public TclClass { public: TcpClass( ) : TclClass(“ Agent/Echo ”) {} TclObject* create(int, const charconst) { return (new EchoAgent ()); } } class echo;

TclObject

Agent

Agent/Echo

TclObject

Agent

EchoAgent

NsObject (^) ??

C++ mirroring OTcl