Virtual Private Network (VPN):VPN network provides the same secure site to site

network connectivity for remote user over the internet.

Why Have VPNs?

VPN Tunnels and Encryption:

VPN Security algorithms:

Symmetric key: Shared secret key is the same key is used by the

sender (for encryption) and the receiver (for decryption).

Shared secret key is often used for long messages.

Data Encryption Standard (DES)

One iteration

Key Exchange—Diffie-Hellman:

Authentication (pre-shared key):

Hash Function (MD5,SHA-1) :is a formula used to convert a variable-length message into

a single string of digits of a fixed length.

VPN protocols :L2TP (layer 2 tunneling protocol): is used to create a media-independent ,

multiprotocol virtual private dialup network (VPDN)…….but it does not provide encryption.

GRE(Generic routing encapsulation ) :  with GRE tunneling cisco router at each site

encapsulates protocol specific packets in IP HEADER creating point to point link to cisco router at other of an Ip cloud ,where the IP header is stripped off .

IPsec( IP security protocol ): is the choice for secure corporate VPNs .it can

provide the security service using internet key exchange (IKE) to handle negotation of protocols and algortithms based on local polivy and to generate the encryption and authentication key to be used by IPSec.

Internet Key Exchange (IKE): used to esablish ashared security policy and authentication keys for services such as

IPSec that require keys . one of its protocols is ISAKMPInternet Security Association and Key

Management Protocol (ISAKMP):   it is protocol used for implementing akey exchange and negotation of security association (SA)

Security association (SA):It is the security database that contains

all the security policy that the VPN will based on.

This security database contains that:1-authentication ,encryption algorithm.2-specification of network traffic.3-IPsec protocols .4-IPsec modes .

IPsec protocols:Encapsulating Security Payload (ESP): a security protocol that provide data

encryption and production with optional authentication …it can completely encapsulates user data

Authentication Header (AH): a security protocol that provide

authentication .it can be used either by itself or with ESP

Tunnel versus Transport Mode:

Tasks to Configure IPSec (site to site)

Task 1 – Prepare for IKE and IPSEC

Task 2 – Configure IKE Task 3 – Configure IPSecTask 4 – Test and Verify IPSEC

Step1- Determine IKE(IKE Phase 1) PolicyDetermine the following policy details:Key distribution method

Authentication method

IPSec peer IP addresses and hostnames

IKE phase 1 policies for all peers

Encryption algorithm

Hash algorithm

IKE SA lifetime

Goal : setup a secure commuication channel for negotiation of

IPSec SA in phase2

Step2-Determine IPSec (IKE Phase 2) PolicyDetermine the following policy details:

IPSec algorithms and parameters for optimal security and performance

IPSec peer details

IP address and applications of hosts to be protected

IKE-initiated Sas

Goal : these are security parameters used to protect data and messages

exchanged between end points

Step 3—Check Current Configuration

Step4- Ensure the Network Works

Step 1—Enable IKE

Step 2—Create IKE Policies

Step 3—Configure ISAKMP Identity

Step4- Verify IKE Configuration

Step1- Configure Transform Sets

Step2- IPSec Security Association Lifetimes

Step 3—Create Crypto ACLs using Extended Access Lists

Purpose of Crypto MapsCrypto maps pull together the various parts

configured for IPSec, including

The traffic to be protected by IPSec and a set of SAs

The local address to be used for the IPSec traffic The destination location of IPSec-protected

traffic The IPSec type to be applied to this traffic

Step 4—Configure IPSec Crypto Maps & apply it to interfaces

Display your configured IKE policies .show crypto isakmp policy Display your configured transform sets.show crypto ipsec transform set

Display security associationsshow crypto isakmp sa

Display the current state of your IPSec SAs.show crypto ipsec sa

Display your configured crypto maps.show crypto map

Enable debug output for IPSec events.debug crypto ipsec

Enable debug output for ISAKMP events.debug crypto isakmp

VPN Remote access:The requirements for VPN Servers include

the need for Internet Security Association and Key Management Protocol (ISAKMP) policies using Diffie-Hellman.

The VPN Remote feature does support transform sets providing Both encryption and authentication ; so it does not support Authentication Header (AH) authentication.

AAA (authentication, authorization and accounting) servers :

are used for more secure access in a remote-access VPN environment.

AAA then checks the following: Who you are (authentication) What you are allowed to do (authorization) What you actually do (accounting)

The accounting information is especially useful for tracking client use for security auditing, billing or reporting purposes

VPN Client: The installation of the Cisco VPN Client is a very

straightforward process. A number of tasks must be completed to establish connectivity to a VPN head-end.

just start setup and the Welcome screen will be presented

The Connection Entries screen is capable of holding multiple entries should multiple access sites. Click the New button at the top of the screen to open the Create New VPN Connection Entry dialog box, shown in Figure

Authentication Tab Group Authentication—A username and

password is necessary to complete the VPN profile.

Transport Tab The Transport tab allows the configuration of

transparent tunneling as well as the choice of whether to use IPsec over UDP or TCP.

Backup Servers Tab: The VPN client contains a Backup Servers

tab to configure a single connection with the capability to connect to multiple servers.

Finish the Connection ConfigurationFrom the main VPN Client window, you can establish

a VPN connection by highlighting one of the profiles and clicking the Connect button at the top of the window. If the connection parameters were properly configured, the VPN connection is successful.

After a VPN connection is established, various statistics about the connection are available.

From the Status pull-down menu, select Statistics. This launches the Statistics window.