CCNA Security
Chapter Eight
Implementing Virtual Private Networks
© 2009 Cisco Learning Institute.
1
Lesson Planning
• This lesson should take 3-4 hours to present
• The lesson should include lecture,
demonstrations, discussions and assessments
• The lesson can be taught in person or using
remote instruction
© 2009 Cisco Learning Institute.
2
Major Concepts
• Describe the purpose and operation of VPN types
• Describe the purpose and operation of GRE VPNs
• Describe the components and operations of IPsec VPNs
• Configure and verify a site-to-site IPsec VPN with preshared key authentication using CLI
• Configure and verify a site-to-site IPsec VPN with preshared key authentication using SDM
• Configure and verify a Remote Access VPN
© 2009 Cisco Learning Institute.
3
Lesson Objectives
Upon completion of this lesson, the successful participant
will be able to:
1. Describe the purpose and operation of VPNs
2. Differentiate between the various types of VPNs
3. Identify the Cisco VPN product line and the security features of
these products
4. Configure a site-to-site VPN GRE tunnel
5. Describe the IPSec protocol and its basic functions
6. Differentiate between AH and ESP
7. Describe the IKE protocol and modes
8. Describe the five steps of IPSec operation
© 2009 Cisco Learning Institute.
4
Lesson Objectives
9. Describe how to prepare IPSec by ensuring that ACLs are
compatible with IPSec
10. Configure IKE policies using the CLI
11. Configure the IPSec transform sets using the CLI
12. Configure the crypto ACLs using the CLI
13. Configure and apply a crypto map using the CLI
14. Describe how to verify and troubleshoot the IPSec configuration
15. Describe how to configure IPSec using SDM
16. Configure a site-to-site VPN using the Quick Setup VPN Wizard
in SDM
17. Configure a site-to-site VPN using the step-by-step VPN Wizard
in SDM
© 2009 Cisco Learning Institute.
5
Lesson Objectives
18. Verify, monitor and troubleshoot VPNs using SDM
19. Describe how an increasing number of organizations are
offering telecommuting options to their employees
20. Differentiate between Remote Access IPSec VPN solutions and
SSL VPNs
21. Describe how SSL is used to establish a secure VPN
connection
22. Describe the Cisco Easy VPN feature
23. Configure a VPN Server using SDM
24. Connect a VPN client using the Cisco VPN Client software
© 2009 Cisco Learning Institute.
6
What is a VPN?
Business Partner
with a Cisco Router
Mobile Worker
with a Cisco
VPN Client
CSA
VPN
Internet
Firewall
SOHO with a Cisco
DSL Router
VPN
WAN
VPN
Regional branch with
a VPN enabled
Cisco ISR router
© 2009 Cisco Learning Institute.
Corporate
Network
- Virtual: Information within a private network is
transported over a public network.
- Private: The traffic is encrypted to keep the
data confidential.
7
Layer 3 VPN
IPSec
VPN
Internet
IPSec
SOHO with a Cisco DSL
Router
• Generic routing encapsulation (GRE)
• Multiprotocol Label Switching (MPLS)
• IPSec
© 2009 Cisco Learning Institute.
8
Types of VPN Networks
Remote-access
VPNs
Business Partner
with a Cisco Router
Mobile Worker
with a Cisco
VPN Client
CSA
MARS
VPN
Internet
SOHO with a
Cisco DSL Router
Site-to-Site
VPNs
Firewall
VPN
IP
S
WAN
VPN
Regional branch with
a VPN enabled
Cisco ISR router
Iron Port
CSA
CSA
Web
Email
Server Server
© 2009 Cisco Learning Institute.
CSA
CSA
CSACSA
DNS
9
Site-to-Site VPN
Business Partner
with a Cisco
Router
Hosts send and receive normal
TCP/IP traffic through a VPN gateway
CSA
MARS
VP
N
Internet
SOHO with a
Cisco DSL
Router
Site-to-Site
VPNs
Firewall
VPN
IP
S
WAN
VPN
Regional branch with
a VPN enabled
Cisco ISR router
Iron
Port
CSA
CSA
Web
Email
Server Server
© 2009 Cisco Learning Institute.
CSA
CS
CS A CS
A
A
DNS
10
Remote-Access VPNs
Remote-access
VPNs
Mobile Worker
with a Cisco
VPN Client
CSA
MARS
Internet
Firewall
VPN
Iron Port
IPS
CSA
CSA
Web
Server
© 2009 Cisco Learning Institute.
CSA
Email
Server
CSA
CSA
CSA
DNS
11
VPN Client Software
R1
R1-vpn-cluster.span.com
“R1”
In a remote-access VPN, each host
typically has Cisco VPN Client software
© 2009 Cisco Learning Institute.
12
Cisco IOS SSL VPN
• Provides remote-access
connectivity from any
Internet-enabled host
• Uses a web browser and
SSL encryption
• Delivers two modes of
access:
- Clientless
- Thin client
© 2009 Cisco Learning Institute.
13
Cisco VPN Product Family
Remote-Access
VPN
Site-to-Site VPN
Cisco VPN-Enabled Router
Secondary role
Primary role
Cisco PIX 500 Series Security Appliances
Secondary role
Primary role
Cisco ASA 5500 Series Adaptive Security
Appliances
Primary role
Secondary role
Cisco VPN
3000 Series Concentrators
Primary role
Secondary role
Home Routers
Primary role
Product Choice
© 2009 Cisco Learning Institute.
14
Cisco VPN-Optimized Routers
Remote Office
Cisco Router
Main Office
Cisco Router
Internet
Regional Office
Cisco Router
SOHO
Cisco Router
© 2009 Cisco Learning Institute.
VPN Features:
• Voice and video enabled VPN (V3PN)
• IPSec stateful failover
• DMVPN
• IPSec and Multiprotocol Label Switching
(MPLS) integration
• Cisco Easy VPN
15
Cisco ASA 5500 Series Adaptive
Security Appliances
Central Site
Remote Site
Internet
Intranet
Extranet
Business-to-Business
Remote User
• Flexible platform
• Cisco IOS SSL VPN
• Resilient clustering
• VPN infrastructure for
contemporary applications
• Cisco Easy VPN
• Automatic Cisco VPN
© 2009 Cisco Learning Institute.
• Integrated web-based
management
16
IPSec Clients
A wireless client that is loaded on a pda
Certicom PDA IPsec
VPN Client
Router with
Firewall and
VPN Client
Small Office
Internet
Cisco VPN
Software Client
Software loaded on a PC
A network appliance that connects SOHO LANs to the VPN
Cisco
AnyConnect
VPN Client
Internet
Provides remote users with secure VPN connections
© 2009 Cisco Learning Institute.
17
Hardware Acceleration Modules
• AIM
• Cisco IPSec VPN Shared
Port Adapter (SPA)
• Cisco PIX VPN
Accelerator Card+ (VAC+)
• Enhanced Scalable
Encryption Processing
(SEP-E)
© 2009 Cisco Learning Institute.
Cisco IPsec VPN SPA
18
GRE VPN Overview
© 2009 Cisco Learning Institute.
19
Encapsulation
Encapsulated with GRE
Original IP Packet
© 2009 Cisco Learning Institute.
20
Configuring a GRE Tunnel
Create a tunnel
interface
R1(config)# interface tunnel 0
R1(config–if)# ip address 10.1.1.1 255.255.255.252
R1(config–if)# tunnel source serial 0/0
R1(config–if)# tunnel destination 192.168.5.5
R1(config–if)# tunnel mode gre ip
R1(config–if)#
Assign the tunnel an IP address
R2(config)# interface tunnel 0
R2(config–if)# ip address 10.1.1.2 255.255.255.252
R2(config–if)# tunnel source serial 0/0
R2(config–if)# tunnel destination 192.168.3.3
R2(config–if)# tunnel mode gre ip
R2(config–if)#
Identify the source tunnel interface
Identify the destination of the tunnel
Configure what protocol GRE will encapsulate
© 2009 Cisco Learning Institute.
21
Using GRE
IP
Only
?
User
Traffic
Yes
No
Use
GRE
Tunnel
No
Unicast
Only?
Yes
Use
IPsec
VPN
GRE does not provide encryption
© 2009 Cisco Learning Institute.
22
IPSec Topology
Main Site
Business Partner
with a Cisco Router
Regional Office with a
Cisco PIX Firewall
IPsec
Perimeter
Router
POP
SOHO with a Cisco
SDN/DSL Router
Legacy
Cisco
PIX
Firewall
Legacy
Concentrator
ASA
Mobile Worker with a
Cisco VPN Client
on a Laptop Computer
Corporate
• Works at the network layer, protecting and authenticating IP packets.
- It is a framework of open standards which is algorithm-independent.
- It provides data confidentiality, data integrity, and origin authentication.
© 2009 Cisco Learning Institute.
23
IPSec Framework
Diffie-Hellman
© 2009 Cisco Learning Institute.
DH7
24
Confidentiality
Least secure
Most secure
Key length:
- 56-bits
Key length:
- 56-bits (3 times)
Diffie-Hellman
Key lengths:
-128-bits
DH7
-192
bits
-256-bits
Key length:
- 160-bits
© 2009 Cisco Learning Institute.
25
Integrity
Least secure
Most secure
Key length:
- 128-bits
Diffie-Hellman
© 2009 Cisco Learning Institute.
Key length:
- 160-bits)
DH7
26
Authentication
Diffie-Hellman
© 2009 Cisco Learning Institute.
DH7
27
Pre-shared Key (PSK)
•At the local device, the authentication key and the identity information (device-specific
Diffie-Hellman
DH7authentication is
information)
are sent through a hash algorithm to form hash_I. One-way
established by sending hash_I to the remote device. If the remote device can independently
create the same hash, the local device is authenticated.
• The authentication process continues in the opposite direction. The remote device
combines its identity information with the preshared-based authentication key and sends it
through the hash algorithm to form hash_R. hash_R is sent to the local device. If the local
device can independently create the same hash, the remote device is authenticated.
© 2009 Cisco Learning Institute.
28
RSA Signatures
• At the local device, the authentication key and identity information (device-specific information)
are sent through the hash algorithm forming hash_I. hash_I is encrypted using the local
device's private encryption key creating a digital signature. The digital signature and a digital
certificate are forwarded to the remote device. The public encryption key for decrypting the
signature is included in the digital certificate. The remote device verifies the digital signature by
decrypting it using the public encryption key. The result is hash_I.
• Next, the remote device independently creates hash_I from stored information. If the
calculated hash_I equals the decrypted hash_I, the local device is authenticated. After the
remote device authenticates the local device, the authentication process begins in the opposite
direction and all steps are repeated from the remote device to the local device.
© 2009 Cisco Learning Institute.
29
Secure Key Exchange
Diffie-Hellman
© 2009 Cisco Learning Institute.
DH7
30
IPSec Framework Protocols
Authentication Header
R1
All data is in plaintext.
R2
AH provides the following:
 Authentication
 Integrity
Encapsulating Security Payload
R1
Data payload is encrypted.
R2
ESP provides the following:
 Encryption
 Authentication
 Integrity
© 2009 Cisco Learning Institute.
31
Authentication Header
1. The IP Header and data payload are hashed
IP Header + Data + Key
R2
Hash
IP HDR
Authentication Data
(00ABCDEF)
IP HDR
AH
Data
IP Header + Data + Key
3. The new packet is
Internet
transmitted to the
IPSec peer router
Hash
Data
2. The hash builds a new AH
header which is prepended
to theR1original packet
© 2009 Cisco Learning Institute.
AH
Recomputed Received
Hash = Hash
(00ABCDEF)
(00ABCDEF)
4. The peer router hashes the IP
header and data payload, extracts
the transmitted hash and compares
32
ESP
Diffie-Hellman
© 2009 Cisco Learning Institute.
DH7
33
Function of ESP
Internet
Router
Router
IP HDR
Data
New IP HDR
IP HDR
ESP HDR
IP HDR
Data
Data
ESP ESP
Trailer Auth
Encrypted
Authenticated
• Provides confidentiality with encryption
• Provides integrity with authentication
© 2009 Cisco Learning Institute.
34
Mode Types
Data
IP HDR
Original data prior to selection of IPSec protocol mode
Transport Mode
IP HDR
Encrypted
Data
ESP HDR
ESP ESP
Trailer Auth
Authenticated
Encrypted
Tunnel Mode
New IP HDR
ESP HDR
IP HDR
Data
ESP ESP
Trailer Auth
Authenticated
© 2009 Cisco Learning Institute.
35
Security Associations
IPSec parameters are configured using IKE
© 2009 Cisco Learning Institute.
36
IKE Phases
R1
Host A
R2
Host B
10.0.2.3
10.0.1.3
IKE Phase 1 Exchange
1. Negotiate IKE policy sets
Policy 10
DES
MD5
pre-share
DH1
lifetime
Policy 15
DES
MD5
pre-share
DH1
lifetime
1. Negotiate IKE policy sets
2. DH key exchange
2. DH key exchange
3. Verify the peer identity
3. Verify the peer identity
IKE Phase 2 Exchange
Negotiate IPsec policy
© 2009 Cisco Learning Institute.
Negotiate IPsec policy
37
IKE Phase 1 – First Exchange
R1
Host A
R2
Host B
Negotiate IKE Proposals
10.0.1.3
Policy 10
DES
MD5
pre-share
DH1
lifetime
IKE Policy Sets
10.0.2.3
Policy 15
DES
MD5
pre-share
DH1
lifetime
Policy 20
3DES
SHA
pre-share
DH1
lifetime
Negotiates matching IKE policies to protect IKE exchange
© 2009 Cisco Learning Institute.
38
IKE Phase 1 – Second Exchange
Establish DH Key
Private value, XA
Public value, YA
YA = g XA mod p
Alice
Private value, XB
Public value, YB
Y = gXB mod p
Bob
B
YA
YB
XA
(YB )
mod p = K
XB
(YA )
mod p = K
A DH exchange is performed to establish keying material.
© 2009 Cisco Learning Institute.
39
IKE Phase 1 – Third Exchange
Authenticate Peer
Remote Office
Corporate Office
Internet
HR
Servers
Peer
Authentication
Peer authentication methods
• PSKs
• RSA signatures
• RSA encrypted nonces
A bidirectional IKE SA is now established.
© 2009 Cisco Learning Institute.
40
IKE Phase 1 – Aggressive Mode
R1
Host A
R2
Host B
10.0.2.3
10.0.1.3
IKE Phase 1 Aggressive Mode Exchange
1.Send IKE policy set
and R1’s DH key
Policy 10
DES
MD5
pre-share
DH1
lifetime
3.Calculate shared
secret, verify peer
identify, and confirm
with peer
Policy 15
DES
MD5
pre-share
DH1
lifetime
2.
Confirm IKE policy
set, calculate
shared secret and
send R2’s DH key
4.
Authenticate peer
and begin Phase 2.
IKE Phase 2 Exchange
Negotiate IPsec policy
© 2009 Cisco Learning Institute.
Negotiate IPsec policy
41
IKE Phase 2
R1
Host A
10.0.1.3
R2
Negotiate IPsec
Security Parameters
Host B
10.0.2.3
• IKE negotiates matching IPsec policies.
• Upon completion, unidirectional IPsec Security
Associations(SA) are established for each protocol and
algorithm combination.
© 2009 Cisco Learning Institute.
42
IPSec VPN Negotiation
10.0.1.3
R1
R2
10.0.2.3
1. Host A sends interesting traffic to Host B.
2. R1 and R2 negotiate an IKE Phase 1 session.
IKE SA
IKE Phase 1
IKE SA
3. R1 and R2 negotiate an IKE Phase 2 session.
IPsec SA
IKE Phase 2
IPsec SA
4. Information is exchanged via IPsec tunnel.
IPsec Tunnel
5. The IPsec tunnel is terminated.
© 2009 Cisco Learning Institute.
43
Configuring IPsec
Tasks to Configure IPsec:
Task 1: Ensure that ACLs are compatible with IPsec.
Task 2: Create ISAKMP (IKE) policy.
Task 3: Configure IPsec transform set.
Task 4: Create a crypto ACL.
Task 5: Create and apply the crypto map.
© 2009 Cisco Learning Institute.
44
Task 1
Configure Compatible ACLs
Site 1
AH
ESP
IKE
10.0.1.0/24
10.0.1.3
Site 2
10.0.2.0/24
R2
R1
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
• Ensure that protocols 50 (ESP), 51 (AH) and UDP port 500 (ISAKMP)
traffic are not blocked by incoming ACLs on interfaces used by IPsec.
© 2009 Cisco Learning Institute.
45
Permitting Traffic
AH
ESP
IKE
Site 1
10.0.1.0/24
10.0.1.3
Site 2
10.0.2.0/24
R2
R1
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
R1(config)# access-list 102 permit ahp host 172.30.2.2 host 172.30.1.2
R1(config)# access-list 102 permit esp host 172.30.2.2 host 172.30.1.2
R1(config)# access-list 102 permit udp host 172.30.2.2 host 172.30.1.2 eq isakmp
R1(config)#
R1(config)# interface Serial0/0/0
R1(config-if)# ip address 172.30.1.2 255.255.255.0
R1(config-if)# ip access-group 102 in
!
R1(config)# exit
R1#
R1# show access-lists
access-list 102 permit ahp host 172.30.2.2 host 172.30.1.2
access-list 102 permit esp host 172.30.2.2 host 172.30.1.2
access-list 102 permit udp host 172.30.2.2 host 172.30.1.2 eq isakmp
R1#
© 2009 Cisco Learning Institute.
46
Task 2
Configure IKE
10.0.2.0/24
10.0.1.0/24
10.0.1.3
R2
R1
10.0.2.3
Internet
Site 1
Site 2
Policy 110
DES
MD5
Preshare
86400
DH1
Tunnel
router(config)#
crypto isakmp policy priority
Defines the parameters within the IKE policy
R1(config)# crypto
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
© 2009 Cisco Learning Institute.
isakmp policy 110
authentication pre-share
encryption des
group 1
hash md5
lifetime 86400
47
ISAKMP Parameters
Parameter
Keyword
Accepted Values
Default
Description
Value
encryption
des
3des
aes
aes 192
aes 256
56-bit Data Encryption Standard
Triple DES
128-bit AES
192-bit AES
256-bit AES
des
Message encryption
algorithm
hash
sha
md5
SHA-1 (HMAC variant)
MD5 (HMAC variant)
sha
Message integrity
(Hash) algorithm
preshared keys
RSA encrypted nonces
RSA signatures
rsa-sig
pre-share
authenticati
rsa-encr
on
rsa-sig
group
1
2
5
768-bit Diffie-Hellman (DH)
1024-bit DH
1536-bit DH
1
lifetime
seconds
Can specify any number of
seconds
86,400 sec
(one day)
© 2009 Cisco Learning Institute.
Peer authentication
method
Key exchange
parameters (DH
group identifier)
ISAKMP-established
SA lifetime
48
Multiple Policies
10.0.1.0/24
10.0.1.3
10.0.2.0/24
R2
R1
Internet
Site 2
Site 1
R1(config)#
crypto isakmp policy 100
hash md5
authentication pre-share
!
crypto isakmp policy 200
hash sha
authentication rsa-sig
!
crypto isakmp policy 300
hash md5
authentication pre-share
© 2009 Cisco Learning Institute.
10.0.2.3
R2(config)#
crypto isakmp policy 100
hash md5
authentication pre-share
!
crypto isakmp policy 200
hash sha
authentication rsa-sig
!
crypto isakmp policy 300
hash md5
authentication rsa-sig
49
Policy Negotiations
R1 attempts to establish a VPN tunnel with
R2 and sends its IKE policy parameters
10.0.1.0/24
10.0.1.3
10.0.2.0/24
R2
R1
10.0.2.3
Internet
Site 1
Preshare
3DES
SHA
DH2
43200
R1(config)# crypto
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
© 2009 Cisco Learning Institute.
Site 2
Policy 110
Tunnel
isakmp policy 110
authentication pre-share
encryption 3des
group 2
hash sha
lifetime 43200
R2 must have an ISAKMP policy
configured with the same parameters.
R2(config)# crypto
R2(config–isakmp)#
R2(config–isakmp)#
R2(config–isakmp)#
R2(config–isakmp)#
R2(config–isakmp)#
isakmp policy 100
authentication pre-share
encryption 3des
group 2
hash sha
lifetime 43200
50
Crypto ISAKMP Key
router(config)#
crypto isakmp key keystring address peer-address
router(config)#
crypto isakmp key keystring hostname hostname
Parameter
keystring
peeraddress
hostname
Description
This parameter specifies the PSK. Use any combination of alphanumeric characters
up to 128 bytes. This PSK must be identical on both peers.
This parameter specifies the IP address of the remote peer.
This parameter specifies the hostname of the remote peer.
This is the peer hostname concatenated with its domain name (for example,
myhost.domain.com).
• The peer-address or peer-hostname can be used, but must be
used consistently between peers.
• If the peer-hostname is used, then the crypto isakmp
identity hostname command must also be configured.
© 2009 Cisco Learning Institute.
51
Sample Configuration
10.0.1.0/24
10.0.2.0/24
Internet
Site 1
R1(config)# crypto
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
R1(config–isakmp)#
R1(config-isakmp)#
R1(config)# crypto
R1(config)#
10.0.2.3
Site 2
isakmp policy 110
authentication pre-share
encryption 3des
group 2
hash sha
lifetime 43200
exit
isakmp key cisco123 address 172.30.2.2
Note:
• The keystring cisco1234 matches.
• The address identity method is
specified.
• The ISAKMP policies are compatible.
• Default values do not have to be
configured.
© 2009 Cisco Learning Institute.
R2
R1
10.0.1.3
R2(config)# crypto
R2(config–isakmp)#
R2(config–isakmp)#
R2(config–isakmp)#
R2(config–isakmp)#
R2(config–isakmp)#
R2(config-isakmp)#
R2(config)# crypto
R2(config)#
isakmp policy 110
authentication pre-share
encryption 3des
group 2
hash sha
lifetime 43200
exit
isakmp key cisco123 address 172.30.1.2
52
Task 3
Configure the Transform Set
router(config)#
crypto ipsec transform–set transform-set-name
transform1 [transform2] [transform3]]
crypto ipsec transform-set Parameters
Command
transform-set-name
Description
This parameter specifies the name of the transform set
to create (or modify).
Type of transform set. You may specify up to four
"transforms": one Authentication Header (AH), one
transform1,
Encapsulating Security Payload (ESP) encryption, one
transform2, transform3
ESP authentication. These transforms define the IP
Security (IPSec) security protocols and algorithms.
A transform set is a combination of IPsec transforms that enact a
security policy for traffic.
© 2009 Cisco Learning Institute.
53
Transform Sets
Host A
R1
172.30.1.2
Internet
10.0.1.3
transform-set ALPHA
esp-3des
tunnel
Host B
R2
172.30.2.2
1
10.0.2.3
transform-set RED
esp-des
tunnel
2
3
transform-set BETA
esp-des, esp-md5-hmac
tunnel
4
transform-set BLUE
esp-des, ah-sha-hmac
tunnel
5
6
7
transform-set CHARLIE
esp-3des, esp-sha-hmac
tunnel
8
9
Match
transform-set YELLOW
esp-3des, esp-sha-hmac
tunnel
• Transform sets are negotiated during IKE Phase 2.
• The 9th attempt found matching transform sets (CHARLIE - YELLOW).
© 2009 Cisco Learning Institute.
54
Sample Configuration
Site 1
10.0.1.3
R1
A
Site 2
R2
172.30.1.2
Internet
B
172.30.2.2
10.0.2.3
R1(config)# crypto isakmp key cisco123 address 172.30.2.2
R1(config)# crypto ipsec transform-set MYSET esp-aes 128
R1(cfg-crypto-trans)# exit
R1(config)#
Note:
• Peers must share the
same transform set
settings.
R2(config)# crypto isakmp key cisco123 address 172.30.1.2
R2(config)#crypto ipsec transform-set OTHERSET esp-aes 128
R2(cfg-crypto-trans)# exit
• Names are only locally
significant.
© 2009 Cisco Learning Institute.
55
Task 4
Configure the Crypto ACLs
Host A
R1
Internet
Outbound
Traffic
Encrypt
Bypass (Plaintext)
Inbound
Traffic
Permit
Bypass
Discard (Plaintext)
• Outbound indicates the data flow to be protected by IPsec.
• Inbound filters and discards traffic that should have been
protected by IPsec.
© 2009 Cisco Learning Institute.
56
Command Syntax
Site 1
Site 2
10.0.1.0/24
10.0.2.0/24
R2
R1
10.0.1.3
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
router(config)#
access-list access-list-number [dynamic dynamic-name [timeout minutes]]{deny |
permit} protocol source source-wildcard destination destination-wildcard
[precedence precedence] [tos tos] [log]
access-list access-list-number Parameters
access-list access-list-number
Command
permit
deny
Description
This option causes all IP traffic that matches the specified conditions to be protected by
cryptography, using the policy described by the corresponding crypto map entry.
This option instructs the router to route traffic in plaintext.
protocol
This option specifies which traffic to protect by cryptography based on the protocol,
such as TCP, UDP, or ICMP. If the protocol is IP, then all traffic IP traffic that matches
that permit statement is encrypted.
source and destination
If the ACL statement is a permit statement, these are the networks, subnets, or hosts
between which traffic should be protected. If the ACL statement is a deny statement,
then the traffic between the specified source and destination is sent in plaintext.
© 2009 Cisco Learning Institute.
57
Symmetric Crypto ACLs
Site 2
Site 1
10.0.2.0/24
10.0.1.0/24
10.0.1.3
R2
R1
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
S0/1
Applied to R1 S0/0/0 outbound traffic:
R1(config)# access-list 110 permit tcp 10.0.1.0 0.0.0.255 10.0.2.0 0.0.0.255
(when evaluating inbound traffic– source: 10.0.2.0, destination: 10.0.1.0)
Applied to R2 S0/0/0 outbound traffic:
R2(config)# access-list 101 permit tcp 10.0.2.0 0.0.0.255 10.0.1.0 0.0.0.255
(when evaluating inbound traffic- source: 10.0.1.0, destination: 10.0.2.0)
© 2009 Cisco Learning Institute.
58
Task 5
Apply the Crypto Map
Site 1
Site 2
R2
R1
Internet
10.0.1.3
10.0.2.3
Crypto maps define the following:
 ACL to be used
 Remote VPN peers
Encrypted Traffic
 Transform set to be used
 Key management method
 SA lifetimes
© 2009 Cisco Learning Institute.
Router
Interface
or Subinterface
59
Crypto Map Command
router(config)#
crypto map map-name seq-num ipsec-manual
crypto map map-name seq-num ipsec-isakmp [dynamic dynamic-map-name]
crypto map Parameters
Command Parameters
Description
map-name
Defines the name assigned to the crypto map set or indicates the name of the crypto
map to edit.
seq-num
The number assigned to the crypto map entry.
ipsec-manual
Indicates that ISAKMP will not be used to establish the IPsec SAs.
ipsec-isakmp
Indicates that ISAKMP will be used to establish the IPsec SAs.
cisco
(Default value) Indicates that CET will be used instead of IPsec for protecting the
traffic.
dynamic
(Optional) Specifies that this crypto map entry references a preexisting static crypto
map. If this keyword is used, none of the crypto map configuration commands are
available.
dynamic-map-name
(Optional) Specifies the name of the dynamic crypto map set that should be used as
the policy template.
© 2009 Cisco Learning Institute.
60
Crypto Map Configuration
Mode Commands
Command
Description
set
peer [hostname | ipaddress]
pfs [group1 | group2]
transform-set
[set_name(s)]
security-association
lifetime
match address [accesslist-id | name]
no
exit
© 2009 Cisco Learning Institute.
Used with the peer, pfs, transform-set, and security-association
commands.
Specifies the allowed IPsec peer by IP address or hostname.
Specifies DH Group 1 or Group 2.
Specify list of transform sets in priority order. When the ipsec-manual
parameter is used with the crypto map command, then only one transform set
can be defined. When the ipsec-isakmp parameter or the dynamic parameter
is used with the crypto map command, up to six transform sets can be
specified.
Sets SA lifetime parameters in seconds or kilobytes.
Identifies the extended ACL by its name or number. The value should match
the access-list-number or name argument of a previously defined IP-extended
ACL being matched.
Used to delete commands entered with the set command.
Exits crypto map configuration mode.
61
Sample Configuration
Site 1
Site 2
10.0.1.0/24
10.0.2.0/24
R2
R1
10.0.1.3
10.0.2.3
Internet
S0/0/0
172.30.2.2
R3
S0/0/0
172.30.3.2
R1(config)# crypto map
R1(config-crypto-map)#
R1(config-crypto-map)#
R1(config-crypto-map)#
R1(config-crypto-map)#
R1(config-crypto-map)#
R1(config-crypto-map)#
MYMAP 10 ipsec-isakmp
match address 110
set peer 172.30.2.2 default
set peer 172.30.3.2
set pfs group1
set transform-set mine
set security-association lifetime seconds 86400
Multiple peers can be specified for redundancy.
© 2009 Cisco Learning Institute.
62
Assign the Crypto Map Set
Site 1
Site 2
10.0.1.0/24
10.0.2.0/24
R2
R1
10.0.1.3
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
MYMAP
router(config-if)#
crypto map map-name
R1(config)# interface serial0/0/0
R1(config-if)# crypto map MYMAP
• Applies the crypto map to outgoing interface
• Activates the IPsec policy
© 2009 Cisco Learning Institute.
63
CLI Commands
Show Command
Description
show crypto map
Displays configured crypto maps
show crypto isakmp policy
Displays configured IKE policies
show crypto ipsec sa
show crypto ipsec
transform-set
debug crypto isakmp
debug crypto ipsec
© 2009 Cisco Learning Institute.
Displays established IPsec tunnels
Displays configured IPsec transform
sets
Debugs IKE events
Debugs IPsec events
64
show crypto map
10.0.1.3
Site 1
Site 2
10.0.1.0/24
10.0.2.0/24
R2
R1
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
router#
show crypto map
Displays the currently configured crypto maps
R1# show crypto map
Crypto Map “MYMAP" 10 ipsec-isakmp
Peer = 172.30.2.2
Extended IP access list 110
access-list 102 permit ip host 10.0.1.3 host 10.0.2.3
Current peer: 172.30.2.2
Security association lifetime: 4608000 kilobytes/3600 seconds
PFS (Y/N): N
Transform sets={ MYSET, }
© 2009 Cisco Learning Institute.
65
show crypto isakmp policy
10.0.1.3
Site 1
Site 2
10.0.1.0/24
10.0.2.0/24
R2
R1
10.0.2.3
Internet
router#
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
show crypto isakmp policy
R1# show crypto isakmp policy
Protection suite of priority 110
encryption algorithm:
3DES - Data Encryption Standard (168 bit keys).
hash algorithm:
Secure Hash Standard
authentication method: preshared
Diffie-Hellman group:
#2 (1024 bit)
lifetime:
86400 seconds, no volume limit
Default protection suite
encryption algorithm:
DES - Data Encryption Standard (56 bit keys).
hash algorithm:
Secure Hash Standard
authentication method: Rivest-Shamir-Adleman Signature
Diffie-Hellman group:
#1 (768 bit)
lifetime:
86400 seconds, no volume limit
© 2009 Cisco Learning Institute.
66
show crypto ipsec transform-set
10.0.1.3
Site 1
Site 2
10.0.1.0/24
10.0.2.0/24
R2
R1
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
show crypto ipsec transform-set
Displays the currently defined transform sets
R1# show crypto ipsec transform-set
Transform set AES_SHA: { esp-128-aes esp-sha-hmac }
will negotiate = { Tunnel, },
© 2009 Cisco Learning Institute.
67
show crypto ipsec sa
10.0.1.3
Site 1
Site 2
10.0.1.0/24
10.0.2.0/24
R2
R1
10.0.2.3
Internet
S0/0/0
172.30.1.2
S0/0/0
172.30.2.2
R1# show crypto ipsec sa
Interface: Serial0/0/0
Crypto map tag: MYMAP, local addr. 172.30.1.2
local ident (addr/mask/prot/port): (172.30.1.2/255.255.255.255/0/0)
remote ident (addr/mask/prot/port): (172.30.2.2/255.255.255.255/0/0)
current_peer: 172.30.2.2
PERMIT, flacs={origin_is_acl,}
#pkts encaps: 21, #pkts encrypt: 21, #pkts digest 0
#pkts decaps: 21, #pkts decrypt: 21, #pkts verify 0
#send errors 0, #recv errors 0
local crypto endpt.: 172.30.1.2, remote crypto endpt.: 172.30.2.2
path mtu 1500, media mtu 1500
current outbound spi: 8AE1C9C
© 2009 Cisco Learning Institute.
68
debug crypto isakmp
router#
debug crypto isakmp
1d00h:
offers
1d00h:
1d00h:
ISAKMP (0:1): atts are not acceptable. Next payload is 0 1d00h: ISAKMP (0:1); no
accepted!
ISAKMP (0:1): SA not acceptable!
%CRYPTO-6-IKMP_MODE_FAILURE: Processing of Main Mode failed with peer at 172.30.2.2
• This is an example of the Main Mode error message.
• The failure of Main Mode suggests that the Phase I policy
does not match on both sides.
• Verify that the Phase I policy is on both peers and ensure that
all the attributes match.
© 2009 Cisco Learning Institute.
69
Starting a VPN Wizard
1. Click Configure in main toolbar
1
3
2
2. Click the VPN button
to open the VPN page
Wizards for IPsec
Solutions, includes
type of VPNs and
Individual IPsec
components
3. Choose a wizard
4. Click the VPN
implementation subtype
4
VPN implementation
Subtypes. Vary based
On VPN wizard chosen.
5
5. Click the Launch the
Selected Task button
© 2009 Cisco Learning Institute.
70
VPN Components
VPN Wizards
SSL VPN parameters
Individual IPsec
components used
to build VPNs
Easy VPN server parameters
VPN Components
Public key certificate
parameters
Encrypt VPN passwords
© 2009 Cisco Learning Institute.
71
Configuring a Site-to-Site VPN
Choose Configure > VPN > Site-to-Site VPN
Click the Create a Site-to-Site VPN
Click the Launch the Selected Task button
© 2009 Cisco Learning Institute.
72
Site-to-Site VPN Wizard
Choose the wizard mode
Click Next to proceed to the configuration of parameters.
© 2009 Cisco Learning Institute.
73
Quick Setup
Configure the parameters
• Interface to use
• Peer identity information
• Authentication method
• Traffic to encrypt
© 2009 Cisco Learning Institute.
74
Verify Parameters
© 2009 Cisco Learning Institute.
75
Step-by-Step Wizard
Choose the outside
interface that is used
1 to connect to the
IPSec peer
2 Specify the IP
address of the peer
3
Choose the authentication
method and specify the
credentials
4 Click Next
© 2009 Cisco Learning Institute.
76
Creating a Custom IKE Proposal
Make the selections to configure
2 the IKE Policy and click OK
1
Click Add to define a proposal
© 2009 Cisco Learning Institute.
3 Click Next
77
Creating a Custom IPSec
Transform Set
Define and specify the transform
set name, integrity algorithm,
encryption algorithm, mode of
operation and optional compression
2
1
Click Add
© 2009 Cisco Learning Institute.
3
Click Next
78
Protecting Traffic
Subnet to Subnet
Click Protect All Traffic Between the Following subnets
1
2
Define the IP address
and subnet mask of the
local network
© 2009 Cisco Learning Institute.
3
Define the IP address
and subnet mask of the
remote network
79
Protecting Traffic
Custom ACL
Click the ellipses button
to choose an existing ACL
or create a new one
1
2
Click the Create/Select an Access-List
for IPSec Traffic radio button
3
To use an existing ACL, choose the Select an Existing
Rule (ACL) option. To create a new ACL, choose the
Create a New Rule (ACL) and Select option
© 2009 Cisco Learning Institute.
80
Add a Rule
1
Give the access rule a
name and description
2
Click Add
© 2009 Cisco Learning Institute.
81
Configuring a New Rule Entry
Choose an action and enter a description of the rule entry
1
2
Define the source hosts or networks in the Source Host/Network pane
and the destination hosts or network in the Destination/Host Network pane
3
(Optional) To provide protection for specific protocols, choose
the specific protocol radio box and desired port numbers
© 2009 Cisco Learning Institute.
82
Configuration Summary
• Click Back to modify the configuration.
• Click Finish to complete the configuration.
© 2009 Cisco Learning Institute.
83
Verify VPN Configuration
Choose Configure > VPN > Site-to-Site VPN > Edit Site-to-Site VPN
Check VPN status.
Create a mirroring configuration if
no Cisco SDM is available on the
peer.
Test the VPN
configuration.
© 2009 Cisco Learning Institute.
84
Monitor
Choose Monitor > VPN Status > IPSec Tunnels
1
Lists all IPsec tunnels, their
parameters, and status.
© 2009 Cisco Learning Institute.
85
Telecommuting
• Flexibility in working
location and working
hours
• Employers save on realestate, utility and other
overhead costs
• Succeeds if program is
voluntary, subject to
management discretion,
and operationally feasible
© 2009 Cisco Learning Institute.
86
Telecommuting Benefits
• Organizational benefits:
- Continuity of operations
- Increased responsiveness
- Secure, reliable, and manageable access to information
- Cost-effective integration of data, voice, video, and applications
- Increased employee productivity, satisfaction, and retention
• Social benefits:
- Increased employment opportunities for marginalized groups
- Less travel and commuter related stress
• Environmental benefits:
- Reduced carbon footprints, both for individual workers and
organizations
© 2009 Cisco Learning Institute.
87
Implementing Remote Access
© 2009 Cisco Learning Institute.
88
Methods for Deploying
Remote Access
IPsec Remote
Access VPN
© 2009 Cisco Learning Institute.
Any
Application
Anywhere
Access
SSL-Based
VPN
89
Comparison of SSL and IPSec
SSL
IPsec
Applications
Web-enabled applications, file sharing, e-mail
All IP-based applications
Encryption
Moderate
Key lengths from 40 bits to 128 bits
Stronger
Key lengths from 56 bits to 256 bits
Authentication
Moderate
One-way or two-way authentication
Strong
Two-way authentication using shared secrets
or digital certificates
Ease of Use
Very high
Moderate
Can be challenging to nontechnical users
Overall Security
Moderate
Any device can connect
Strong
Only specific devices with specific
configurations can connect
© 2009 Cisco Learning Institute.
90
SSL VPNs
• Integrated security and routing
• Browser-based full network SSL VPN access
SSL VPN
Internet
Headquarters
SSL VPN
Tunnel
© 2009 Cisco Learning Institute.
Workplace
Resources
91
Types of Access
© 2009 Cisco Learning Institute.
92
Full Tunnel Client Access Mode
© 2009 Cisco Learning Institute.
93
Establishing an SSL Session
1
2
User using
SSL client
3
4
5
© 2009 Cisco Learning Institute.
User makes a connection
to TCP port 443
Router replies with a
digitally signed public key
User software creates a
shared-secret key
SSL VPN
enabled ISR
router
Shared-secret key, encrypted
with public key of the server, is
sent to the router
Bulk encryption occurs using the
shared-secret key with a
symmetric encryption algorithm
94
SSL VPN Design Considerations
• User connectivity
• Router feature
• Infrastructure planning
• Implementation scope
© 2009 Cisco Learning Institute.
95
Cisco Easy VPN
• Negotiates tunnel parameters
• Establishes tunnels according to
set parameters
• Automatically creates a NAT /
PAT and associated ACLs
• Authenticates users by
usernames, group names,
and passwords
• Manages security keys for
encryption and decryption
• Authenticates, encrypts, and
decrypts data through the tunnel
© 2009 Cisco Learning Institute.
96
Cisco Easy VPN
© 2009 Cisco Learning Institute.
97
Securing the VPN
1
Initiate IKE Phase 1
2
Establish ISAKMP
SA
3
Accept Proposal1
4
Username/Password
Challenge
Username/Password
5
System Parameters Pushed
6
7
© 2009 Cisco Learning Institute.
Reverse Router Injection
(RRI) adds a static route
entry on the router for the
remote clients IP address
Initiate IKE Phase 2: IPsec
IPsec SA
98
Configuring Cisco Easy VPN Server
1
4
3
2
5
© 2009 Cisco Learning Institute.
99
Configuring IKE Proposals
Specify required parameters
2
1
Click Add
© 2009 Cisco Learning Institute.
3
Click OK
100
Creating an IPSec Transform Set
3
1
2
4
© 2009 Cisco Learning Institute.
101
Group Authorization and Group
Policy Lookup
1
Select the location where
Easy VPN group policies
can be stored
2
5
Click Next
3
Click Add
4
Click Next
Configure the local
group policies
© 2009 Cisco Learning Institute.
102
Summary of Configuration
Parameters
© 2009 Cisco Learning Institute.
103
VPN Client Overview
R1
R1
R1-vpn-cluster.span.com
R1-vpn-cluster.span.com
• Establishes end-to-end, encrypted VPN tunnels for
secure connectivity
• Compatible with all Cisco VPN products
• Supports the innovative Cisco Easy VPN capabilities
© 2009 Cisco Learning Institute.
104
Establishing a Connection
R1-vpn-cluster.span.com
Once
authenticated,
status changes to
connected.
R1
R1-vpn-cluster.span.com
“R1”
© 2009 Cisco Learning Institute.
105
© 2009 Cisco Learning Institute.
106