RE © 2003, Cisco Systems, Inc. All rights reserved.

RE162 Module 14 PIX VPN

RE163 Learning Objectives Upon completion of this module, you will be able to perform the following tasks: –Identify how the PIX Firewall enables a secure VPN. –Identify the tasks to configure PIX Firewall IPSec support. –Identify the commands to configure PIX Firewall IPSec support. –Configure a VPN between PIX Firewalls. –Describe the Cisco VPN Client.

Overview This module will cover the creation and configuration of secure VPNs. VPNs are a very useful tool in securing traffic between two remote networks. Both site-to-site and remote access VPNs will be covered.

Key Terms IPSec IKE DES, 3DES, AES SHA-1, MD5 RSA Digital Certificates Pre-shared keys Diffie-Hellman

RE166 The PIX Firewall Enables a Secure VPN

RE167 PIX Firewall VPN Topologies

RE168 IPSec Enables PIX Firewall VPN Features –Data confidentiality –Data integrity –Data authentication –Anti-replay

RE169 What Is IPSec? IETF standard that enables encrypted communication between peers –Consists of open standards for securing private communications. –Network layer encryption ensuring data confidentiality, integrity, and authentication. –Scales from small to very large networks. –Included in PIX Firewall version 5.0 and later.

RE1610 IPSec Standards Supported by the PIX Firewall –IPSec (IP Security protocol) Authentication Header (AH) Encapsulating Security Payload (ESP) –Internet Key Exchange (IKE) –Data Encryption Standard (DES) –Triple DES (3DES) –Diffie-Hellman (DH) –Message Digest 5 (MD5) –Secure Hash Algorithm (SHA) –Ravist, Shamir, Adelman signatures (RSA) –Certificate Authorities (CA)

RE1611 IPSec Configuration Tasks

RE1612 Task 1—Prepare to Configure VPN Support

RE1613 IPSec Configuration Tasks Overview –Task 1—Prepare to configure VPN support. –Task 2—Configure IKE parameters. –Task 3—Configure IPSec parameters. –Task 4—Test and verify VPN configuration.

RE1614 Task 1—Prepare to Configure VPN Support –Step 1—Determine the IKE (IKE phase one) policy. –Step 2—Determine the IPSec (IKE phase two) policy. –Step 3—Ensure that the network works without encryption. –Step 4—Implicitly permit IPSec packets to bypass PIX Firewall access lists, access groups, and conduits.

Plan for IKE

IKE Phase One Policy Parameters

Determine IKE Phase One Policy IKE SA lifetime Authentication method Encryption algorithm Hash algorithm Site 1 86,400 seconds DES SHA Site 2 DES SHA Pre-share Parameter 768-bit D-HKey exchange Pre-share 768-bit D-H 86,400 seconds

Plan for IPSec

Determine IPSec (IKE Phase Two) Policy

RE1620 Ensure the Network Works pixfirewall# ping

RE1621 Ensure ACLs do not Block IPSec Traffic

RE1622 Task 2—Configure IKE Parameters

RE1623 Step 1—Enable or Disable IKE –Enables or disables IKE on the PIX Firewall interfaces. –IKE is enabled by default. –Disable IKE on interfaces not used for IPSec. isakmp enable interface-name pixfirewall (config)# pixfirewall(config)# isakmp enable outside

RE1624 Step 2—Configure an IKE Phase One Policy –Creates a policy suite grouped by priority number. –Creates policy suites that match peers. –Can use default values. pixfirewall(config)# isakmp policy 10 encryption des pixfirewall(config)# isakmp policy 10 hash sha pixfirewall(config)# isakmp policy 10 authentication pre-share pixfirewall(config)# isakmp policy 10 group 1 pixfirewall(config)# isakmp policy 10 lifetime 86400

RE1625 isakmp key keystring address peer-address [netmask] pixfirewall(config)# Step 3—Configure the IKE Pre-shared Key –Pre-shared keystring must be identical at both peers. –Use any combination of alphanumeric characters up to 128 bytes for keystring. –Specify peer-address as a host or wildcard address. –Easy to configure, yet is not scalable. pixfirewall(config)# isakmp key cisco123 address

RE1626 pixfirewall# show isakmp policy Protection suite of priority 10 encryption algorithm: DES - Data Encryption Standard (56 bit keys). hash algorithm: Secure Hash Standard authentication method: Pre-Shared Key Diffie-Hellman group: #1 (768 bit) lifetime: 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: seconds, no volume limit Step 4—Verify IKE Phase One Policies –Displays configured and default IKE protection suites.

RE1627 Task 3—Configure IPSec Parameters

RE1628 access-list acl_ID {deny | permit} protocol source_addr source_mask destination_addr destination_mask pixfirewall(config)# Step 1—Configure Interesting Traffic –permit = encrypt –deny = do not encrypt –access-list selects IP traffic by address, network, or subnet pixfirewall# access-list 101 permit ip host host

pix1(config)# show static static (inside,outside) netmask pix1(config)# show access-list access-list 110 permit ip host host PIX1 pix6(config)# show static static (inside,outside) netmask pix2(config)# show access-list access-list 101 permit ip host host PIX6 Example Crypto ACLs –Lists should always be symmetrical.

RE1630 crypto ipsec transform-set transform-set-name transform1 [transform2 [transform3]] pixfirewall(config)# Step 2—Configure an IPSec Transform Set –Sets are limited to up to one AH and up to two ESP transforms. –Default mode is tunnel. –Configure matching sets between IPSec peers. pix1(config)# crypto ipsec transform-set pix6 esp-des

RE1631 Available IPSec Transforms ah-md5-hmac AH-HMAC-MD5 transform ah-sha-hmac AH-HMAC-SHA transform esp-des ESP transform using DES cipher (56 bits) esp-3des ESP transform using 3DES cipher(168 bits) esp-md5-hmac ESP transform using HMAC-MD5 auth esp-sha-hmac ESP transform using HMAC-SHA auth

RE1632 Step 3—Configure the Crypto Map –Specifies IPSec (IKE phase two) parameters. –Map names and sequence numbers group entries into a policy. pixfirewall(config)# crypto map MYMAP 10 ipsec-isakmp pixfirewall(config)# crypto map MYMAP 10 match address 101 pixfirewall(config)# crypto map MYMAP 10 set peer pixfirewall(config)# crypto map MYMAP 10 set transform-set pix6 pixfirewall(config)# crypto map MYMAP 10 set pfs group1 pixfirewall(config)# crypto map MYMAP 10 set security- association lifetime seconds 28800

RE1633 crypto map map-name interface interface-name pixfirewall(config)# Step 4—Apply the Crypto Map to an Interface –Applies the crypto map to an interface. –Activates IPSec policy. pixfirewall(config)# crypto map MYMAP interface outside

pix1(config)# show crypto map Crypto Map "peer2" 10 ipsec-isakmp Peer = access-list 101 permit ip host host (hitcnt=0) Current peer: Security association lifetime: kilobytes/28800 seconds PFS (Y/N): N Transform sets={ pix2, } Example Crypto Map for PIX1

pix2(config)# show crypto map Crypto Map "peer1" 10 ipsec-isakmp Peer = access-list 101 permit ip host host (hitcnt=0) Current peer: Security association lifetime: kilobytes/28800 seconds PFS (Y/N): N Transform sets={ pix1, } Example Crypto Map for PIX2

RE1636 Task 4—Test and Verify VPN Configuration

RE1637 Task 4—Test and Verify VPN Configuration –Verify ACLs and interesting traffic. show access-list –Verify correct IKE configuration. show isakmp show isakmp policy –Verify correct IPSec configuration. show crypto ipsec transform-set

RE1638 Task 4—Test and Verify VPN Configuration (cont.) –Verify the correct crypto map configuration. show crypto map –Clear the IPSec SA. clear crypto ipsec sa –Clear the IKE SA. clear crypto isakmp sa –Debug IKE and IPSec traffic through the PIX Firewall. debug crypto ipsec debug crypto isakmp

RE1639 The Cisco VPN Client

Topology Overview

RE1641 Cisco VPN Client Features –Support for Windows ME, Windows 2000, and Windows XP –Data compression –Split tunneling –User authentication by way of VPN central-site device –Automatic VPN Client configuration –Internal MTU adjustment –CLI to the VPN Dialer –Start Before Logon –Software update notifications from the VPN device upon connection

RE1642 PIX Firewall to VPN Client Pre-Shared Example pixfirewall# write terminal access-list 80 permit ip ip address outside ip address inside ip local pool MYPOOL nat (inside) 0 access-list 80 route outside aaa-server MYTACACS protocol tacacs+ aaa-server MYTACACS (inside) host tacacskey timeout 5 aaa authentication include any inbound MYTACACS sysopt connection permit-ipsec crypto ipsec transform-set AAADES esp-des esp-md5-hmac crypto dynamic-map DYNOMAP 10 set transform-set AAADES

RE1643 PIX Firewall to VPN Client Pre-Shared Example (cont.) pixfirewall# write terminal crypto map VPNPEER 20 ipsec-isakmp dynamic DYNOMAP crypto map VPNPEER client authentication MYTACACS crypto map VPNPEER interface outside isakmp enable outside isakmp identity address isakmp policy 10 authentication pre-share isakmp policy 10 encryption des isakmp policy 10 hash md5 isakmp policy 10 group 2 isakmp policy 10 lifetime vpngroup TRAINING address-pool MYPOOL vpngroup TRAINING idle-time 1800 vpngroup TRAINING password ********

RE1644 VPN Client to PIX Firewall Example –A new connection entry named vpnpeer0 is created. –The remote server IP is the PIX Firewall outside interface. vpnpeer0

RE1645 VPN Client to PIX Firewall Example (cont.) –The group name matches the vpngroup name in the PIX Firewall. –The password is the pre-shared key and must match the vpngroup password. –You can use the digital certificate for authentication. TRAINING

PIX Firewall Assigns the IP Address to the VPN Client

RE1647 Scale PIX Firewall VPNs

CA Server Fulfilling Requests from IPSec Peers Each IPSec peer individually enrolls with the CA server.

RE1649 Enroll a PIX Firewall with a CA –Configure CA support –Generate public or private keys –Authenticate the CA –Request signed certificates from the CA –CA administrator verifies request and sends signed certificates

RE1650 Summary

RE1651 Summary –The PIX Firewall enables a secure VPN. –IPSec configuration tasks include configuring IKE and IPSec parameters. –CAs enable scaling to a large number of IPSec peers. –Remote users can establish secure VPN tunnels between PCs running Cisco VPN Client software and any Cisco VPN-enabled product, such as the PIX Firewall, that supports the Unified Client framework.

RE1652 © 2003, Cisco Systems, Inc. All rights reserved.