6.1 Overview of IPsec
 Benefits of IPsec
 Recommended Uses of IPsec
 Tools Used to Configure IPsec
 What are Connection Security Rules ?
Benefits of IPsec
 IPsec – suite of protocols that allows secure, encrypted
communication between 2 computers over an
unsecured network
 2 goals; to protect IP packet & to defend against
network attacks
 IPsec secures network traffic by using encryption &
data signing
 An IPsec policy defines the type of traffic that Ipsec
examines, how that traffic is secured & encrypted, and
how IPsec peers are authenticated
Recommended Uses of IPsec
 Authenticating & encrypting host-to-host traffic
 Authenticating & encrypting traffic to servers
 Layer 2 Tunneling Protocol (L2TP)/IPsec for VPN
connections
 Site-to-site (gateway-to-gateway) tunneling
 Enforcing logical networks (server/domain isolation)
Tools Used to Configure IPsec
 Windows Firewall with Advanced Security MMC (used
for Windows Server 2008 & Windows Vista)
 IP Security Policy MMC (used for mixed environments
& to configure policies that apply to all Windows
versions)
 Netsh command-line tool
What are Connection Security Rules?
 Connection security rules involve:
- Authenticating 2 computers before they begin

-
communications
Securing information being sent between 2 computers
Using key exchange, authentication, data integrity & data
encryption (optionally)
How firewall rules & connection rules are related:
Firewall rules allow traffic through, but do not secure that
traffic
Connection security rules can secure the traffic, but
creating a connection security rule does not allow traffic
through the firewall
6.2 Configuring Connection
Security Rules
 Choosing a Connection Security Rule Type
 What are Endpoints?
 Choosing Authentication Requirements
 Authentication Methods
 Determining a Usage Profile
Choosing a Connection Security Rule
Type
Rule Type
Description
Isolation
Restricts connections based on authentication
criteria that you define
Authentication Exemption
•Exempts specific computers, or a group or range
of IP addresses, from being required to
authenticate
•Grants access to those infrastructure computers
with which this computer must communicate
before authentication occurs
Server-to-server
Authenticates 2 specific computers, 2 groups of
computers, 2 subnets, or specific computer & a
group of computers or subnet
Tunnel
Provides secure communications between 2 peer
computers through tunnel endpoints (VPN or
L2TP IPsec tunnels)
Custom
Enables you to create a rule with special settings
What are Endpoints?
 Computer endpoints are the computers or the group of
computers that form peers for the connection
 IPsec tunnel mode protects an entire IP packet by
treating it as an AH or ESP payload
 ESP encrypts packets and applies a new unencryptes
header to facilitate routing
 ESP function in 2 modes:
1. Transport mode
2. Tunnel mode
ESP Transport Mode
IP HDR
IP HDR
Data
ESP
HDR
Encrypted
Data
ESP
TRLR
ESP
Auth
ESP Tunnel Mode
IP HDR
New IP
HDR
ESP
HDR
Data
Encrypted
IP Packet
ESP
TRLR
ESP
Auth
Choosing Authentication Requirements
Option
Description
Request Authentication for inbound
and outbound connections
Ask that all inbound/outbound traffic
be authenticated, but allow the
connection if authentication fails
Require authentication for inbound
connections and request authentication
for outbound connections
•Require inbound be authenticated or it
will be blocked
•Outbound can be authentication fails
Require authentication for inbound and Require that all inbound/outbound
outbound connections
traffic be authenticated or the traffic
will be blocked
Authentication Methods
Method
Key Points
Default
Use the authentication method configured on the IPsec
Settings tab
Computer & User (Kerberos
V5)
You can request or require both the user & computer
authenticate before communications can continue; domain
membership required
Computer (Kerberos V5)
Request or require the computer to authenticate using
Kerberos V5
User (Kerberos v5)
Request or require the user to authenticate using Kerberos
V5; domain membership required
Computer certificate
•Request or require a valid computer certificate, requires at
least one CA
•Only accept health certificates: request or require a valid
health certificate to authenticate, requires IPsec NAP
Advanced
Configure any available method; you can specify methods
for First & Second Authentication
Determining a Usage Profile
 Security settings can change dynamically with the network

-

location type
Windows supports 3 network types :
Domain: selected when the computer is a domain member
Private: networks trusted by the user (home or small office
network)
Public: default for newly detected networks, usually the
most restrictive settings are assigned because of the
security risks present on public networks
The network location type is most useful on portable
computers which are likely to move from network to
network
6.3 Configuring IPsec NAP
Enforcement
 IPsec Enforcement for Logical Networks
 IPsec NAP Enforcement Processes
 Requirements to Deploy IPsec NAP Enforcement
IPsec Enforcement for Logical Networks
HRA
VPN
802.1x
DHCP
NPS proxy
SHAs
NAP agent
NAP ECs
NAP administration server
Network policies
NAP health policies
Connection request policies
SHVs
NAP enforcement
servers
SHAs
NAP agent
NAP ECs
NPS servers
Non-compliant
NAP client
Remediation
servers
Certificate services
Email servers
NAP policy servers
Non-NAP
Capable client
Restricted
network
Secure
servers
Boundary
Network
Secure Network
Compliant
NAP client
IPsec NAP Enforcement Processes
IPsec NAP Enforcement
includes:
• Policy validation
• NAP enforcement
• Network restriction
• Remediation
• Ongoing monitoring of
compliance
VPN Server
Active
Directory
IEEE 802.1x
Devices
Health
Registration
Authority
Internet
DHCP Server
Intranet
Perimeter
Network
NAP Health
Policy Server
Restricted
network
Remediation
Server
NAP Client with
limited access
Requirements to Deploy IPsec NAP
Enforcement
 Active Directory
 Active Directory Certificate Services
 Network Policy Server
 Health Registration Authority
6.4 Monitoring IPsec Activity
 Tools used to Monitor IPsec
 Using IP Security Monitor to Monitor Ipsec
 Using Windows Firewall with Advanced Security to
Monitor IPsec
Tools Used to Monitor IPsec
Tool
Key Points
• Used in Windows XP and higher
IP Security Monitor
• MMC snap-in
• Administrators can monitor local and remote IPsec
policy usage
• Only available in Windows 2000
IPsecmon
• Command-line tool
• Reduced level of information available for
troubleshooting
Windows Firewall
with Advanced
Security MMC
New in Windows Vista and Windows Server 2008
• Trace file found in: systemroot\debug\oakley.log
Detailed IKE
tracing using Netsh • Enabled in Windows XP and Windows 2000
through Registry modification
Using IP Security Monitor to Monitor
IPsec
Options for using the IP Security Monitor:
• Modify IPsec data refresh interval to update information in the
console at a set interval
• Allow DNS name resolution for IP addresses to provide additional
information about computers connecting with IPsec
• Computers can monitored remotely:
•
To enable remote management editing, the
HKLM\system\currentcontrolset\services\policyagent key
must have a value of 1
• To Discover the Active security policy on a computer, examine
the Active Policy Node in the IP Security Monitoring MMC
• Main Mode Monitoring monitors initial IKE and SA:
•
Information about the Internet Key Exchange
• Quick Mode Monitoring monitors subsequent key exchanges
related to IPsec:
•
Information about the IPsec driver
Using Windows Firewall with Advanced
Security to Monitor IPsec
The Windows Firewall in Windows Vista and Windows Server 2008 incorporates
IPsec
• Use the Connection Security Rules
and Security Associations nodes to
monitor IPsec connections
• The Connection Security Rules and
Security Associations nodes will not
monitor policies defined in the
IP Security Policy snap-in
• Items that can be monitored include:
•
Security Associations
•
Main Mode
•
Quick Mode
6.5 Troubleshooting IPsec
 IPsec Troubleshooting Process
 Troubleshooting Internet Key Exchange (IKE)
 Troubleshooting IKE Negotiation Events
IPsec Troubleshooting Process
1
2
Stop the IPsec Policy Agent and use the ping command to
verify communications
Verify firewall settings
3
Start the IPsec Policy Agent and use IP Security Monitor
to determine if a security association exists
4
Verify that the policies are assigned
5
Review the policies and ensure they are compatible
6
Use IP Security Monitor to ensure that any changes
are applied
Troubleshooting IKE

Identify connectivity issues related with IPsec
and IKE

Identify firewall and port issues

View the Oakley.log file for potential issues

Determine Main mode exchange issues
Troubleshooting IKE Negotiation Events
Common Security Event log codes:
• Success:
•
541 - IKE Main Mode or Quick Mode established
•
542 - IKE Quick Mode was deleted
•
543 - IKE Main Mode was deleted
• Information Log Entries:
•
Largely pertains to monitoring for denial of service attacks
•
There might not be any errors but resources will
run low, which affects performance for legitimate clients
• Quick Mode audit failures are denoted with 547 error message
End of Chapter 6