Man-in-the-middle attack Network Compromises and Attacks
2.4.3.5 Replay attack
A replay attack is essentially what would happen if an attacker were to record a transmission from A to B, even if the attacker is unable to read the message, then replay the message at a later time. Sometimes attacks of this nature can work if used in concert with an IP spoofing assault or even a man-in-the-middle one. Some VPNs combat this threat by serializing the packets, some by encapsulating the IP header as well as the datagram, and some by using synchronized timestamping. A combination of these techniques could also be used.2.4.3.6 Detection and cleanup
Computer break-in incidents are difficult to detect and more difficult to prosecute. According to the Computer Emergency Response Team CERT, a full 35 of all high-degree break-ins go completely undetected by the system administrators responsible for the equipment compromised; an even higher 85 of all incidents go unreported. Sometimes it is only by accident that an administrator notices the tell-tale symptoms of a break-in. Strange things found in the temporary directory, strange processes running, applications found that were not distributed with the operating system, and users reporting that they are having trouble logging in or have forgotten their passwords somehow are clues. When attackers are careful to clean up after themselves, the odds that someone will notice decrease dramatically. If they are careless or just joyriders, detection is much easier and cleanup is simpler. The biggest gut-wrenching feeling occurs when the attacker seems not to have changed anything. If only a minimal clue to their penetration is left, you can be assured that you need to sanitize—and quickly. For a whole host of security-related documents, including current advisories, check with CERT directly at http:www.cert.org . In closing, always try to be quick to respond to any threat or apparent break-in as soon as you are notified or as soon as you discover it. The faster you are at taking care of things, the less impact there is overall. Even though you are sure to have a restricted budget and inadequate resources for your security efforts, try to follow through with all measures you can take to pursue the attackers. If they think you are too busy or uncaring, they will come back, with better tricks and harsher consequences. Be attentive to what they were trying to do as well as what they did. If you can connect the dots, you may put yourself in front of them, and possibly even catch them. Dont just assume they will disappear or that they didnt really do anything anyway. Just to reiterate: keep good backups, change user accounts and passwords regularly, and develop a registry for access and authentication levels that can be deployed organization-wide.2.5 Patents and Legal Ramifications
Cryptographic routines are complex mathematical systems, and the people who have created them are experts who have spent a great deal of resources to create and protect their systems. 41 As any good lawyer will tell you, intellectual property is just as tangible as real property, and in some cases easier to support in a court of law. Even using some technologies could constitute a legally binding agreement with the softwares creators, so you need to take care when dealing with any and all such systems. The U.S. government classifies all encryption routines as munitions, which is to say that they consider the mathematical formulas that protect data a dangerous technology. Cryptography, to the Feds, is the same as treason, illegal arms trading, smuggling, racketeering, and drug sales. The boys on the Hill do not take such matters lightly, either. You may ask yourself, How could a little code hurt the giant U.S. government or its citizens? To learn exactly why the government treats these technologies with such kid gloves, we have to look back at some historical elements. Remember the enigma box? It was a WWII German code box that scrambled military orders sent from the high command to the field. Along similar lines, the Japanese had developed a system involving a code box called Purple. In times of war, code cracking and encryption take on a very important role, best described by the saying: loose lips sink ships. The protection of even simple communication is of paramount importance to the government. If all the routines developed on U.S. soil were exported abroad with no restrictions and a war were to break out, it would be unclear to our military leaders if their communications were safe. Products and services described in this book may be prohibited from being exported outside of the United States, or crippled in such a way as to make them freely exportable. Generally a reduction in the size of the key used to encrypt the data allows for a license to ship overseas. International organizations are already working on strong world-wide encryption technologies, and we are sure that the next 10 years will paint a new landscape of the data protection universe. One typical legal protection that a cryptographic creator has is the patent. DES, contrary to popular belief, is patented, but it is distributed royalty-free, which is one of the reasons why it pops up almost everywhere. All public key two-key systems are patented as well, by either RSA Data Security Inc., or by the Public Key Partners PKP group see Table 2-1 . Obviously they make it their business to collect license fees and monitor for stray usages of their software. Table 2-1. Cryptographic Patents Encryption Routine Patent Information Hellman-Merkle Patent 4,218,582, expired August 19, 1997. Supposedly covers all public key systems. Rivest-Shamir-Adleman Patent 4,405,829, expires September 2, 2000. Covers the RSA algorithm. Hellman-Pohlig Patent 4,424,414, expires January 3, 2001. Related to Diffie-Hellman expired 1997. Schnorr Patent 4,995,082, expires February 19, 2008. The DSS Algorithm is based on this. Kravitz Patent 5,231,668, expires July 27, 2008. The actual DSS Algorithm.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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