Telco Small to Medium Solutions
3.2.1.2 Hardwaresoftware
VPNs and WANs require the same types of equipment at this level. ISDN or frame relay routers are available through such manufacturers as Cisco Systems, Farallon, Motorola, and Ascend Communications. Both sides of the connection require a router, which connects to the local ISP. The WAN requires no extraneous software to complete the solution. Use the same networking protocol on each end and the network is functioning. The VPN solution requires software of some kind to allow secure access to the central network. SSH, L2F, L2TP, and PPTP are solid solutions for small to medium network-to- network connections. Note that dedicated or specific hardware may be needed to support any of these VPN solutions. SSH is available for Unix servers, L2F and L2TP are supported on Cisco routers running IOS including ISDN and frame relay routers, and PPTP is currently available on Windows NT 4.0 Server, as well as some ISDN routers. Also note that these softwarehardware combinations are required on each end of the connection.3.2.1.3 Administration
Expertise for a traditional WAN setup should be in a typical network administrators skill set. Total set-up time for both sides of the WAN should not exceed 10 to 20 hours, which includes tracking down the best equipment, ordering lines, and configuring the connection. These types of connections do not usually require much recurring maintenance, as they tend to stay solid once properly configured. As much as 10 hours a month in maintenance time is standard, even if there are major connection or configuration problems. The main failure point in this kind of connection is the telco provider, because they dont tend to communicate with their customers when lines are undergoing maintenance or fail completely. Another recurring issue is training end users in the use and general maintenance of the connection, as this scenario would not need a dedicated network administrator on both ends. When implementing a virtual private network, the initial consideration for a network engineer is research and training. Most network administrators need to know how a VPN works and how it fits with the organizations networking needs. This book should get the process started, but an internal needs assessment should be done as well. Initial setup of a VPN will consume a significant amount of time, possibly as much as 20 to 40 hours, including research, training, pitching the solution upstairs, and actually implementing the network. Recurring maintenance shouldnt be significantly different from the WAN solution presented earlier with two exceptions: the ISP used and security of the VPN. Both issues are discussed at length later in this section. However, suffice it to say that the network administrator can add about 5 to 10 hours a month to the WAN maintenance estimate a maximum of 30 hours total per month for dealing with security and the Internet service provider.3.2.1.4 Security, scalability, and stability
The WAN connection is arguably the most secure and stable solution for a network of any size. The connections are entirely private and are using proven, industry standard technology. Any questions concerning the stability of a WAN would affect any network, LAN, WAN, or VPN. Failures of equipment, protocols, systems, and server, for example, while not common, 47 are a fact of life for any network. Where remote-to-central connections are concerned WAN and VPN, the additional failure point is the telco provider. These are beyond the network administrators control, for the most part, and the selection of a telco provider that communicates problems and planned downtimes to its customers is the best bet. VPNs strength is not its stability, in a general sense. VPNs are a new technology, running on an inherently unreliable technology the Internet. When dealing with Internet routing issues, communication between various platforms, encryption processes and the like, you can expect a less robust system. But as the world moves more to an interconnected society and as real standards emerge protocols, hardware, etc., VPNs will have a stabler base on which to operate. The real differences between the VPN and the WAN come to light when scalability is considered. Moving from our simple smallmedium to a large WAN requires a serious investment in equipment, workforce, and telco lines, especially when adding multiple networks across a nationwide organization. The main cost difference would be line charges for the upgrade. If the central office had to upgrade to a T1 with all the equipment necessary for this, the remote sites would likewise need at least a fractional T1 with the equipment necessary to make this work. With the VPN, initially only the central network would need an upgrade in bandwidth and equipment, even to accept connections from multiple networks. Then, boosting the VPN servers capacity becomes minuscule when compared to the equipment and line upgrades on the WAN solution.3.2.2 Large Solutions
Large WAN or VPN scenarios can encompass many different configurations, from multiple large interconnected networks to a central network connecting many smaller networks. For simplicitys sake, we present the two scenarios in Figure 3-5 .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
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