Sample configuration Implementing PC-to-WAN Tunnels
6.4.3.2 Tunnel server configuration
Routing table The tunnel server actually has two separate routing tables with which to direct traffic between the two subnets. Both routing tables are set as default routes for the dynamic tunnel IP addresses see Table 6-1 . Any traffic bound for the second support subnet is relayed to the WAN routers interface for routing. Table 6-1. Routing Tables for Figure 6-3 Routing Table 1 Routing Table 2 Subnet 1.195.6. 1.195.7. Netmask 255.255.255.0 255.255.255.0 Description Sales Subnet Support Subnet Dynamic IP table The dynamic IP range starts at 1.196.5.1 and comprises a Class C network 255 addresses. The tunnel server on the corporate LAN is set up to connect multiple single PC tunnel connections, and routes all tunnel traffic to its two physical subnets from the routing parameters. • Range name : Sales Tunnel. • Range description : Remote Tunnel Clients. • First IP : 1.196.5.1. 105 • Total tunnels : The total number of tunnels for this tunnel group is set to 128. As each tunnel session is assigned two IP addresses, this makes the total IP address range equal to 256 IP addresses. • NetMask : 255.255.255.0 for the 256 IP virtual network. Authentication table The group name for this tunnel is SalesSupport. The password in this case is WHOlistenen. These two parameters have been extracted into an ETA file called salsup.eta and distributed via floppy disk to the various tunnel clients. The key file has been created by the tunnel server on the corporate LAN and is specific to this tunnel group. The key file has also been extracted and distributed via floppy disk. By default, this key file is named salsup.key.6.4.3.3 WAN router configuration
The WAN routers function in this scenario is to route network traffic between the two subnets Sales and Support. All hosts on the two subnets have default routes to the router, which routes traffic either between the two networks or out onto the Internet. The WAN router is likewise configured to route tunnel traffic from the virtual network 1.196.5. to the tunnel server at 1.195.6.2 on port 3265.6.4.3.4 Firewall configuration
The local firewall is configured to relay all external tunnel traffic those reaching 1.195.6.1 on port 3265 to the WAN router at 1.195.6.5. The WAN router then routes the traffic to the tunnel server as in the previous WAN router section.6.4.3.5 Network host configurations
All hosts on both the 1.195.6. subnet and the 1.195.7. subnet are configured with default routes pointing to the WAN router.6.4.3.6 Remote client configurations
The remote PC clients are configured similarly to the methods presented earlier in Section 6.4.2 . The only differences are the names of the ETA and key files. In this case, each PC will have salsup.eta and salsup.key files installed for the SalesSupport tunnel user group.6.4.3.7 Tracing the packets
The remote PC begins by opening a tunnel request to the tunnel server. The PC is connected to the Internet via an ISP and has initiated the tunnel connection with its AltaVista Tunnel Telecommuter client. The request passes through the end users ISP transparently, destined for the remote firewalls IP interface on the Internet 1.195.6.1 on the tunnel port of 3265. The remote firewall is set up to relay all traffic received on this port to the WAN routers interface for its subnet 1.195.6.5. The WAN router then routes this traffic to the tunnel servers physical IP address, at 1.195.6.2 on port 3265. The tunnel server checks the authentication information against its Authentication tables, and encrypts a reply using the remote clients private key. This reply is sent back to the remote client, which decrypts the reply with its private key. The two sides then exchange parts of the session key salsup.key,which isParts
» 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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