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Internet Protocol Security (IPSec)
Reviewing IPSec
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Understanding Vulnerabilities
Threat Analysis
What Is IPSec?
Microsoft IPSec Features
Advantages and Disadvantages of IPSec
IPSec Security Services
Authentication Methods
How IPSec Is Deployed
Threat Analysis
1.
Identify threats
2.
Prioritize threats based on:
Probability of occurrence
Severity of potential damage
3.
Divide the number representing damage by the
number representing probability to determine the
threat level
4.
Address threats with the highest threat levels first
Example
Assume that you have identified two potential threats to your enterprise:
1. Threat A has been identified as having a high amount of damage
(Damage = 10) and a low probability of occurring (Probability = 10),
so the threat level is 1 (10/10 = 1).
2. Threat B has been identified as having a high amount of damage
(Damage = 8) and a fairly high probability of occurring (Probability = 3),
so the threat level is 2.67 (8/3 = 2.67).
Therefore, you would address Threat B first, because it has a higher
threat level.
What Is IPSec?
Can use security
protocols to encrypt or
digitally sign traffic
Can use tunnel mode
to secure traffic
between two networks
Can use transport
mode to secure traffic
between any two hosts
Tunnel Mode
Router
Router
Transport Mode
Router
Internet Protocol Security (IPSec) is a set of extensions to
the Internet Protocol (IP) family.
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It provides cryptographic security services that allow for
authentication, integrity, access control, and confidentiality.
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IPSec services are similar to Secure Sockets Layer (SSL), but at the
network layer, in a way that is completely transparent to your
applications and much more powerful. This is because your
applications do not need to have any knowledge of IPSec to be able
to use it.
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You can create encrypted tunnels, (virtual private networks [VPNs]),
or simply perform encryption between computers.
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The many options offered by IPSec make it much more complex
than SSL.
Microsoft IPSec Features
Implementation
Policy-based configuration
management
IPSec functionality over NAT
Description
Makes configuration, implementation, and
administration easier
Automatically detects the presence of a NAT
device and uses UDP-ESP encapsulation to
allow IPSec traffic to pass through the NAT
IPSec certificate-to-account
mapping
Allows you to set restrictions on which
computers are allowed to connect
Default traffic exemptions
Exempts only Internet Key Exchange (IKE)
traffic from IPSec filtering
Command-line management
Scripts and automates IPSec configuration
Computer startup security
Permits only the following traffic during
computer startup
Persistent policy for
enhanced security
Is applied before the local policy or the Active
Directory–based policy
IPSec is based on an end-to-end security model that establishes trust and
security from a source IP to a destination IP address. Any computers that
only route data from source to destination are not required to support IPSec,
unless firewall-type packet filtering or network address translation (NAT) is
in place.
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This model allows for the successful deployment of IPSec in the following
enterprise scenarios:
Local area network (LAN): client/server and peer-to-peer
Wide area network (WAN): router-to-router and gateway-to-gateway using
IPSec tunnels
Remote access: dial-up clients and Internet access from private networks
IPSec tunnel mode
 When you use IPSec tunnel mode, IPSec encrypts the IP header and the
payload. Tunnel mode provides the protection of an entire IP packet.
IPSec transport mode
 Transport mode is the default mode IPSec encrypts only the IP payload.
Advantages and Disadvantages of IPSec
Advantages
Flexible security protocols
Transparent to users and
applications
Authentication
Confidentiality
Open industry (IETF)
standards
Data integrity
Dynamic rekeying
Secure end-to-end links
Easy implementation and
centralized management by
using policies
Disadvantages
Administrative overhead
Increased performance
requirement
Supportability
Policy management
Local policy configuration
IPSec Security Services
Feature
Description
Automatic key management
IKE services dynamically exchange and
manage keys between communicating
computers
Automatic security
negotiation
IKE services dynamically negotiate a
common set of security settings using IKE
services
Public key infrastructure
support
IPSec supports the use of public key
certificates for authentication
Preshared key support
IPSec can use a preshared key for
authentication
Authentication Methods
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Kerberos V5
The default authentication method for IPSec
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Public key certificates
Using this authentication method, security credentials can be
presented without being compromised in the process
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Preshared key authentication
Both parties agree on a shared, secret key that is used for
authentication in an IPSec policy
How IPSec Is Deployed
Using policy-based management
Easy management
Easy implementation
Eliminates administrative overhead
Using local policies
One local policy
Group Policy settings can be stored on individual
computers
Policy-based configuration management
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You can assign IPSec policies through Group Policy configuration of Active
Directory domains and organizational units.
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This allows the IPSec policy to be assigned at the site, domain, or
organizational unit level, eliminating the administrative overhead of
configuring each computer separately.
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IPSec Encapsulating Security Payload (ESP) packets can now pass
through a NAT device that allows UDP traffic. The Internet Key Exchange
(IKE) protocol automatically detects the presence of a NAT device and uses
UDP.
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ESP encapsulation to allow IPSec traffic to pass through the NAT device.
Refs:
www.microsoft.com
www.wikipedia.com