Virtual private network

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What is the basic concept of IP VPN?
From the security standpoint, VPNs either trust the underlying delivery network, or must enforce security with mechanisms in the VPN itself. Securities and Exchange Commission and the Ontario Securities Commission laid charges against former senior financial officials from Nortel including Frank Dunn who was fired from Nortel in In their paper [41] they allege the NSA specially built a computing cluster to precompute multiplicative subgroups for specific primes and generators, such as for the second Oakley group defined in RFC This section needs additional citations for verification. Addresses starting with fe

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This way operating systems can be retrofitted with IPsec. This method of implementation is also used for both hosts and gateways. However, when retrofitting IPsec the encapsulation of IP packets may cause problems for the automatic path MTU discovery , where the maximum transmission unit MTU size on the network path between two IP hosts is established. If a host or gateway has a separate cryptoprocessor , which is common in the military and can also be found in commercial systems, a so-called bump-in-the-wire BITW implementation of IPsec is possible.

IPsec was developed in conjunction with IPv6 and was originally required to be supported by all standards-compliant implementations of IPv6 before RFC made it only a recommendation. IPsec is most commonly used to secure IPv4 traffic. In , these documents were superseded by RFC and RFC with a few incompatible engineering details, although they were conceptually identical.

In addition, a mutual authentication and key exchange protocol Internet Key Exchange IKE was defined to create and manage security associations. In , as part of Snowden leaks , it was revealed that the US National Security Agency had been actively working to "Insert vulnerabilities into commercial encryption systems, IT systems, networks, and endpoint communications devices used by targets" as part of the Bullrun program.

The OpenBSD IPsec stack was the first implementation that was available under a permissive open-source license, and was therefore copied widely. In the forwarded email from , Theo de Raadt did not at first express an official position on the validity of the claims, apart from the implicit endorsement from forwarding the email. Gregory Perry's email falls into this category. In their paper [41] they allege the NSA specially built a computing cluster to precompute multiplicative subgroups for specific primes and generators, such as for the second Oakley group defined in RFC If an organization were to precompute this group, they could derive the keys being exchanged and decrypt traffic without inserting any software backdoors.

A second alternative explanation that was put forward was that the Equation Group used zero-day exploits against several manufacturers' VPN equipment which were validated by Kaspersky Lab as being tied to the Equation Group [42] and validated by those manufacturers as being real exploits, some of which were zero-day exploits at the time of their exposure. This can be and apparently is targeted by the NSA using offline dictionary attacks. From Wikipedia, the free encyclopedia.

Security Architecture for the Internet Protocol". The spelling "IPsec" is preferred and used throughout this and all related IPsec standards. All other capitalizations of IPsec [ US Naval Research Laboratories. IP Security Document Roadmap. Cryptographic Suites for IPsec. For example, an IPv4 address and its subnet mask may be IP addresses are assigned to a host either dynamically at the time of booting, or permanently by fixed configuration of the host hardware or software.

Persistent configuration is also known as using a static IP address. In contrast, when a computer's IP address is assigned newly each time it restarts, this is known as using a dynamic IP address. The configuration of a static IP address depends in detail on the software or hardware installed in the computer.

Computers used for the network infrastructure, such as routers and mail servers, are typically configured with static addressing, Static addresses are also sometimes convenient for locating servers inside an enterprise. The address assigned with DHCP usually has an expiration period, after which the address may be assigned to another device, or to the originally associated host if it is still powered up. A network administrator may implement a DHCP method so that the same host always receives a specific address.

DHCP is the most frequently used technology for assigning addresses. It avoids the administrative burden of assigning specific static addresses to each device on a network. It also allows devices to share the limited address space on a network if only some of them are online at a particular time.

Typically, dynamic IP configuration is enabled by default in modern desktop operating systems. Dialup and some broadband networks use dynamic address features of the Point-to-Point Protocol. In the absence or failure of static or stateful DHCP address configurations, an operating system may assign an IP address to a network interface using stateless auto-configuration methods, such as Zeroconf. A sticky dynamic IP address is an informal term used by cable and DSL Internet access subscribers to describe a dynamically assigned IP address which seldom changes.

The addresses are usually assigned with DHCP. Since the modems are usually powered on for extended periods of time, the address leases are usually set to long periods and simply renewed. If a modem is turned off and powered up again before the next expiration of the address lease, it often receives the same IP address.

These addresses are only valid on the link, such as a local network segment or point-to-point connection, that a host is connected to. These addresses are not routable and like private addresses cannot be the source or destination of packets traversing the Internet. When the link-local IPv4 address block was reserved, no standards existed for mechanisms of address autoconfiguration. APIPA has been deployed on millions of machines and has, thus, become a de facto standard in the industry.

An IP address conflict occurs when two devices on the same local physical or wireless network claim to have the same IP address.

A second assignment of an address generally stops the IP functionality of one or both of the devices. Many modern operating systems notify the administrator of IP address conflicts. When IP addresses are assigned by multiple people and systems with differing methods, any of them may be at fault. IP addresses are classified into several classes of operational characteristics: It normally refers to a single sender or a single receiver, and can be used for both sending and receiving.

Usually, a unicast address is associated with a single device or host, but a device or host may have more than one unicast address. Some individual PCs have several distinct unicast addresses, each for its own distinct purpose. Sending the same data to multiple unicast addresses requires the sender to send all the data many times over, once for each recipient. Broadcasting is an addressing technique available in IPv4 to send data to all possible destinations on a network in one transmission operation, while all receivers capture the network packet all-hosts broadcast.

In addition, a directed limited broadcast uses the all-ones host address with the network prefix. For example, the destination address used for directed broadcast to devices on the network IPv6 does not implement broadcast addressing, and replaces it with multicast to the specially-defined all-nodes multicast address.

A multicast address is associated with a group of interested receivers. In IPv4, addresses In either case, the sender sends a single datagram from its unicast address to the multicast group address and the intermediary routers take care of making copies and sending them to all receivers that have joined the corresponding multicast group. Like broadcast and multicast, anycast is a one-to-many routing topology.

However, the data stream is not transmitted to all receivers, just the one which the router decides is logically closest in the network. Anycast address is an inherent feature of only IPv6.

In IPv4, anycast addressing implementations typically operate using the shortest-path metric of BGP routing and do not take into account congestion or other attributes of the path. Anycast methods are useful for global load balancing and are commonly used in distributed DNS systems.

A host may use geolocation software to deduce the geolocation of its communicating peer. Public IP addresses may be used for communication between hosts on the global Internet. For security and privacy considerations, network administrators often desire to restrict public Internet traffic within their private networks. The source and destination IP addresses contained in the headers of each IP packet are a convenient means to discriminate traffic by IP address blocking or by selectively tailoring responses to external requests to internal servers.

The basic concept of a VPN is to connect networks in separate offices making them appear as one network or to connect remote individuals to their corporate network making them appear as though they were physically on the same network.

With a VPN separate networks and individuals are "virtually" present. PCs, servers, printers and other devices all see each other as if they were all "local". Employees can interact with each other as though they were in the same building. VPNs connect private networks through public networks like the Internet so they are cheaper, simpler and more flexible than other ways of connecting?

VPNs also use strong encryption to provide privacy and strong authentication to guarantee identity, so they are more secure than traditional networks. The gateways and clients are configured with the private addresses of other locations on the VPN. When they see a packet addressed to a device at one of those locations, they take the original private packet and wrap it inside another packet with public addresses.

The outside packet or wrapper is routed through the Internet to a gateway at the other location. The second gateway removes the wrapper and sends the original private packet onto the local network. This process is known as encapsulation and is the basis for VPN tunnels. When building a VPN one must consider several parameters including cost, security, time to market and performance.

Cost includes both capital cost i. There is a wide range of security implementations from completely unsecured no encryption and no authentication where the VPN simply routes private packets over the public network, to strong security that protects all connections with powerful encryption and digital certificate based authentication. VPNs can be implemented very quickly in simple, homogenous environments that don't change very much, but connecting diverse and changing environments can take a long time and may require the help of VPN experts or even outsourcing.

Finally, VPN performance varies widely and depends on the capabilities of the VPN gateways as well as the quality and performance of the intervening networks.

A VPN can be implemented inexpensively using low cost VPN appliances and consumer Internet connections, but it may not have the performance you're looking for. On the other hand, VPNs that use high quality IP services and more expensive VPN products provide substantially better performance than existing data networks.

It's available free from our Web site, and available here: Please add a title for your question. Meet all of our Networking experts. View all Networking questions and answers. VPN services, enterprises choosing between the technologies should consider factors like Companies are approaching network infrastructure upgrades with SD-WAN deployment, but a new survey shows they're weighing issues