Ease of configuration and maintenance
9.2.2.7 High-speed access
For those with ultra-high-capacity lines, such as fractional or full DS3s T3s, the PIX, with its two 100-megabit Ethernet cards, can easily handle a significant amount of Internet traffic. Although we wouldnt recommend piping a T3s full load of traffic through only one machine, the fact that the capacity is there is quite a benefit.9.2.2.8 Links
By using an additional card that comes separately, the PIX firewall can be used to create an encrypted channel between itself and another such unit somewhere out on the public side of the PIX. This private link encryption feature gives the PIX firewall its most tremendous benefit: it lets organizations link private Internets securely using the public networks, with very simple configuration. Thats what this book is all about. One slight disadvantage is that the PIX firewall supports only IP traffic. We suppose this could be considered an advantage as well.9.2.3 Limitations of the PIX Firewall
Even though the PIX is a nearly complete solution to the development of a virtually private network, it does have some drawbacks in terms of maintenance, network address translation limits, and price.9.2.3.1 Hardware solution
Hardware can be tricky if mismanaged, difficult to debug if misconfigured, and hard to replace quickly if broken. Hardware like the PIX is provided by only one vendor, and you cant be sure what will happen to the vendor in the future.9.2.3.2 Dynamic address use
There is a limited pool of addresses that the PIX can assign to hosts on your internal network that want to communicate with the outside. Cisco sells a few different varieties of the product, allowing for 32, 256, or 1024 sessions simultaneously. Remember that one user could be using many different sessions at once, so there is a definite limit on how much a PIX can handle when its connected to a huge network.9.2.3.3 Budgetary considerations
A whole squadron of Cisco PIX units might be prohibitively expensive to widely distribute across your network. The PIX firewall has a suggested retail price in the tens of thousands of dollars, and the encryption cards required to create VPN tunnels go for a few thousand each.9.2.3.4 Maintenance
As with any new equipment, you have to consider the need for ongoing maintenance and growth. The PIX firewall, which may be initially easy to configure, could grow to have a complex configuration even if there are no other firewalls providing a similar function. The persons in charge of coordinating network activity need to establish a plan for how traffic needs to be restricted, and to which networks these restrictions apply. Subtle mistakes in the configuration could lead to potentially large security holes. 1509.3 Configuring the PIX as a Gateway
The PIX firewall comes standard with two switchable 10100 Megabit Ethernet cards, a serial console port, a failover control card, some required cabling and mounting parts, and possibly a secure encryption card, depending on the bundle purchased. In this section we will set up a PIX unit right out of the box, configure it for basic operation, and set up an average firewall. Beyond that, we will illustrate the setup of multiple PIX units so that they may link to one another across the Internet, thus creating a VPN. In this section, we show you how to connect to the PIX so you can configure it, how to set up your firewall on the PIX, and how to do some initial testing. Configuration of the PIX doesnt affect configuration of any other hosts on the inner or outer networks, which you can still set up using traditional rules. The configuration examples in this chapter were set up using the 4.1.6 version of the PIX operating software.9.3.1 Connecting to the PIX
Example 9-1 shows the PIX boot screen, which is sent to the console port when the unit powers on. A serial console cable, supplied with the unit, must be attached to a personal computer, and the terminal software must be configured as follows before any commands may be input into the system: • 9600 baud • 8 bits, no parity, 1 stop bit To confirm that the connections are made properly and that the terminal software is set up right, simply booting the PIX firewall should produce the output seen in Example 9-1 . Example 9-1. PIX Console Startup Screen Copyright c 1996-1998 by Cisco Systems, Inc. Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph c of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph c 1 ii of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. Cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134-1706 Type ? for help armadillo 09.3.2 A Sample Configuration
The configuration of the firewall is pretty straightforward. Given our test scenario featured in Figure 9-2 , we have developed a configuration that meets those requirements. Here are the configuration parameters we entered into our PIX:Parts
» Virtual Private Networks 2nd 1999
» How VPNs relate to Intranets
» What Are We Protecting with Our VPN?
» Firewalls How VPNs Solve Internet Security Issues
» Authentication How VPNs Solve Internet Security Issues
» Encryption How VPNs Solve Internet Security Issues
» Tunneling How VPNs Solve Internet Security Issues
» A Note on IP Address and Domain Name Conventions Used in This Book
» Packet restriction or packet filtering routers
» Bastion host What Types of Firewalls Are There?
» DMZ or perimeter zone network
» Proxy servers What Types of Firewalls Are There?
» A Brief History of Cryptography
» Cryptography: How to Keep a Secret
» Cryptography in Network Communications
» Hash algorithms Cryptographic Algorithms
» Secret key systems Cryptographic Algorithms
» Public key cryptosystems Cryptographic Algorithms
» Use of Cryptosystems and Authentication in a VPN
» ESP Encapsulating Security Payload
» AH Authentication Header VPN Protocols
» Internet Key Exchange, ISAMKPOakley
» ISO X.509 v.3 Digital Certificates
» LDAP Lightweight Directory Access Protocol Radius
» PPTP Point-to-Point Tunneling Protocol
» Basic Firewalling Methodologies for Compromising VPNs
» Ciphertext-only attack Cryptographic Assaults
» Known plaintext attack Cryptographic Assaults
» Chosen plaintext attack Cryptographic Assaults
» Chosen ciphertext attack Cryptographic Assaults
» Brute force attacks Cryptographic Assaults
» Password guessers and dictionary attacks
» Social engineering Cryptographic Assaults
» Address spoofing Network Compromises and Attacks
» Session hijacking Network Compromises and Attacks
» Man-in-the-middle attack Network Compromises and Attacks
» Replay attack Network Compromises and Attacks
» Detection and cleanup Network Compromises and Attacks
» Patents and Legal Ramifications
» General WAN, RAS, and VPN Concepts
» Telco Small to Medium Solutions
» Security, scalability, and stability
» Hardwaresoftware Small to Medium Solutions
» Administration Small to Medium Solutions
» Hardwaresoftware Administration Security, scalability, and stability
» Differences Between PPTP, L2F, and L2TP
» Dialing into an ISP That Supports PPTP
» Dialing into an ISP That Doesnt Support PPTP
» Where PPTP Fits into Our Scenario
» The encapsulation process Dissecting a PPTP Packet
» Accept encrypted authentication RAS authentication methods
» Accept Microsoft encrypted authentication
» Accept any authentication, including clear text
» Data encryption PPTP Security
» Availability Features of PPTP
» Easy Implementation Features of PPTP
» Multiprotocol Tunneling Features of PPTP
» Ability to Use Corporate and UnregisteredIP Addresses
» Choosing the protocols to tunnel
» Choosing your authentication method
» IP address negotiation using DHCP
» Outbound authentication using PPTP filtering
» Filtering caveats PPTP Filtering
» Installing PPTP Filtering by IP Address
» Configuring Users for Dial-up Access
» Configuring PPTP for Dial-up Networking on a Windows NT Client
» Configuring PPTP for Dial-up Networking on a Windows 95 or 98 Client
» Setting up global PPTP parameters Setting up a port for PPTP
» Configuring PPTP on an Ascend MAX 4004
» Making the Calls Configuring and Testing Layer 2 Connections
» The Event Viewer Login problems
» The Dial-Up Networking Monitor
» ping and traceroute Connectivity Testing
» Fixed IP addresses How to Allow PPTP Through Firewalls
» How PPTP Can Bypass a Proxy Server
» Three-part encryption technique Security
» Support for an emerging security standard
» Support for Security Dynamics SecureID
» Accessibility Flexibility Advantages of the AltaVista Tunnel System
» Platform Limitations AltaVista Tunnel Limitations
» Extranet server System Considerations
» Telecommuter client System Considerations
» Planning How the AltaVista Tunnel Works
» AltaVista Tunnel Extranet server
» Security procedures The Guts
» AltaVista Tunnel Telecommuter Client
» Sample configuration Implementing a LAN-to-LAN Tunnel
» Tunnel server configuration Implementing a LAN-to-LAN Tunnel
» Firewall configuration Host configuration
» Sample configuration Implementing Single Connections-to-LAN Tunnels
» Tunnel server configuration Implementing Single Connections-to-LAN Tunnels
» Firewall configuration Implementing Single Connections-to-LAN Tunnels
» Local host configuration Implementing Single Connections-to-LAN Tunnels
» Remote PC configuration Implementing Single Connections-to-LAN Tunnels
» Sample configuration Implementing PC-to-WAN Tunnels
» Tunnel server configuration Implementing PC-to-WAN Tunnels
» Tracing the packets Implementing PC-to-WAN Tunnels
» Preparing to Install Installing the AltaVista Tunnel
» Windows NT 4.0 Installing the AltaVista Tunnel Extranet Serverfor Windows NT
» Installing the AltaVista Tunnel Telecommuter Client for Windows
» Installing the AltaVista Tunnel Telecommuter Client for MacOS
» Initial configuration Adding Routes and Dynamic Addresses
» Managing routes and dynamic IPs
» Group configuration Adding Tunnel Groups
» Tunnel client information Adding Tunnel Groups
» Tools for Tunnel Management Changing Port Settings
» Rekey Interval and Minimum Encryption Settings
» Configuring Unix-to-Windows NT Tunnel Connections
» Getting Busy Configuring the AltaVista Telecommuter Client
» Tunnel Server and Client Configuration Checks
» Local Network and Internet Gateway Configuration Checks
» Encryption Capabilities The SSH Software
» Useful sshd parameters for our purposes
» Understanding SSH authentication ssh
» Useful ssh parameters for our purposes
» The VPN Components Creating a VPN with PPP and SSH
» Setting up the master and slave Linux systems
» Creating a user account on the slave
» Setting up SSH authentication
» Configuring sudo on the slave
» Putting pty-redir on the master
» Setting up the slaves scripts
» Testing the Connection Creating a VPN with PPP and SSH
» A Performance Evaluation Creating a VPN with the Unix Secure Shell
» ISP Assigned Addresses Global Pool
» Hardware solution Advantages of the PIX Firewall
» Superior to Unix and other router firewalls
» Single point of controlfailure
» Dynamic address translation Advantages of the PIX Firewall
» PIX acts like a proxy server
» Ease of configuration and maintenance
» High-speed access Advantages of the PIX Firewall
» Links Advantages of the PIX Firewall
» Hardware solution Limitations of the PIX Firewall
» Dynamic address use Limitations of the PIX Firewall
» Budgetary considerations Limitations of the PIX Firewall
» Maintenance Limitations of the PIX Firewall
» A Sample Configuration Configuring the PIX as a Gateway
» Firewall Configuration on the PIX
» debug xlate Testing, Tracing, and Debugging
» arp Testing, Tracing, and Debugging
» show interface Testing, Tracing, and Debugging
» Offering Services to the Internet Through Conduits and the static Command
» Tunneling with the link Directive
» Choosing an ISP Managing and Maintaining Your VPN
» Connectivity Problems Solving VPN Problems
» Authentication Errors Solving VPN Problems
» Routing Problems Dealing with an ISP
» Compatibility with Other Products
» Delivering Quality of Service
» Restrict What VPN Users Can Get To
» Avoid Public DNS Information for VPN Servers and Routers
» Keeping Yourself Up-to-Date Managing and Maintaining Your VPN
» Network Connections Hardware and Operating System VPN Package
» Connection Hardware and Operating System VPN Package
» Connection Hardware and Operating System
» VPN Package Remote Access Users
Show more