Virtual Private Networks: Private Internet Access For Mac
Kathryn Garivay
A virtual private network (VPN) is a mechanism for creating a secure connection between a computing device and a computer network, or between two networks, using an insecure communication medium such as the public Internet.[1]
A VPN can extend access to a private network (one that disallows or restricts public access) to users who do not have direct access to it, such as an office network allowing secure access from off-site over the Internet.[2]
A VPN is created by establishing a virtual point-to-point connection through the use of tunneling protocols over existing networks. A VPN available from the public Internet can provide some of the benefits[example needed] of a private wide area network (WAN).[4]
Typically, individuals interact with remote access VPNs, whereas businesses tend to make use of site-to-site connections for business-to-business, cloud computing, and branch office scenarios. However, these technologies are not mutually exclusive and, in a significantly complex business network, may be combined to enable remote access to resources located at any given site, such as an ordering system that resides in a data center.
VPNs cannot make online connections completely anonymous, but they can increase privacy and security by encrypting all communication between remote locations over the open Internet. To prevent disclosure of private information or data sniffing, VPNs typically allow only authenticated remote access using[clarification needed] tunneling protocols and secure encryption techniques.
Tunnel endpoints must be authenticated before secure VPN tunnels can be established.[citation needed] User-created remote-access VPNs may use passwords, biometrics, two-factor authentication, or other cryptographic methods. Network-to-network tunnels often use passwords or digital certificates. Depending on the VPN protocol, they may store the key to allow the VPN tunnel to establish automatically, without intervention from the administrator. Data packets are secured by tamper proofing via a message authentication code (MAC), which prevents the message from being altered or tampered without being rejected due to the MAC not matching with the altered data packet.
Tunneling protocols can operate in a point-to-point network topology however, this would theoretically not be considered a VPN because a VPN by definition is expected to support arbitrary and changing sets of network nodes. But since most router implementations support a virtual, software-defined tunnel interface, customer-provisioned VPNs often are simply[ambiguous] defined tunnels running conventional routing protocols.
A device at the edge of the customer's network which provides access to the PPVPN. Sometimes it is just a demarcation point between provider and customer responsibility. Other providers allow customers to configure it.
A device, or set of devices, at the edge of the provider network that connects to customer networks through CE devices and presents the provider's view of the customer site. PEs are aware of the VPNs that connect through them, and maintain VPN state.
A device that operates inside the provider's core network and does not directly interface to any customer endpoint. It might, for example, provide routing for many provider-operated tunnels that belong to different customers' PPVPNs. While the P device is a key part of implementing PPVPNs, it is not itself VPN-aware and does not maintain VPN state. Its principal role is allowing the service provider to scale its PPVPN offerings, for example, by acting as an aggregation point for multiple PEs. P-to-P connections, in such a role, often are high-capacity optical links between major locations of providers.
VLAN is a Layer 2 technique that allows for the coexistence of multiple local area network (LAN) broadcast domains interconnected via trunks using the IEEE 802.1Q trunking protocol. Other trunking protocols have been used but have become obsolete, including Inter-Switch Link (ISL), IEEE 802.10 (originally a security protocol but a subset was introduced for trunking), and ATM LAN Emulation (LANE).
Developed by Institute of Electrical and Electronics Engineers, VLANs allow multiple tagged LANs to share common trunking. VLANs frequently comprise only customer-owned facilities. Whereas VPLS as described in the above section (OSI Layer 1 services) supports emulation of both point-to-point and point-to-multipoint topologies, the method discussed here extends Layer 2 technologies such as 802.1d and 802.1q LAN trunking to run over transports such as metro Ethernet.
As used in this context, a VPLS is a Layer 2 PPVPN, emulating the full functionality of a traditional LAN. From a user standpoint, a VPLS makes it possible to interconnect several LAN segments in a way that is transparent to the user, making the separate LAN segments behave as one single LAN.[22]
PW is similar to VPLS but can provide different L2 protocols at both ends. Typically, its interface is a WAN protocol such as Asynchronous Transfer Mode or Frame Relay. In contrast, when aiming to provide the appearance of a LAN contiguous between two or more locations, the Virtual Private LAN service or IPLS would be appropriate.
EtherIP (RFC 3378)[23] is an Ethernet-over-IP tunneling protocol specification. EtherIP has only a packet encapsulation mechanism. It has no confidentiality or message integrity protection. EtherIP was introduced in the FreeBSD network stack[24] and the SoftEther VPN[25] server program.
Ethernet VPN (EVPN) is an advanced solution for providing Ethernet services over IP-MPLS networks. In contrast to the VPLS architectures, EVPN enables control-plane-based MAC (and MAC,IP) learning in the network. PEs participating in the EVPN instances learn the customer's MAC (MAC,IP) routes in control-plane using MP-BGP protocol. Control-plane MAC learning brings a number of benefits that allow EVPN to address the VPLS shortcomings, including support for multi-homing with per-flow load balancing and avoidance of unnecessary flooding over the MPLS core network to multiple PEs participating in the P2MP/MP2MP L2VPN (in the occurrence, for instance, of ARP query). It is defined RFC 7432.
This section discusses the main architectures for PPVPNs, one where the PE disambiguates duplicate addresses in a single routing instance, and the other, virtual router, in which the PE contains a virtual router instance per VPN. The former approach, and its variants, have gained the most attention.
One of the challenges of PPVPNs involves different customers using the same address space, especially the IPv4 private address space.[26] The provider must be able to disambiguate overlapping addresses in the multiple customers' PPVPNs.
In the method defined by RFC 2547, BGP extensions advertise routes in the IPv4 VPN address family, which are in the form of 12-byte strings, beginning with an 8-byte route distinguisher (RD) and ending with a 4-byte IPv4 address. RDs disambiguate otherwise duplicate addresses in the same PE.[citation needed]
PEs understand the topology of each VPN, which is interconnected with MPLS tunnels directly or via P routers. In MPLS terminology, the P routers are label switch routers without awareness of VPNs.[citation needed]
The virtual router architecture,[27][28] as opposed to BGP/MPLS techniques, requires no modification to existing routing protocols such as BGP. By the provisioning of logically independent routing domains, the customer operating a VPN is completely responsible for the address space. In the various MPLS tunnels, the different PPVPNs are disambiguated by their label but do not need routing distinguishers.[citation needed]
Some virtual networks use tunneling protocols without encryption to protect the privacy of data. While VPNs often provide security, an unencrypted overlay network does not fit within the secure or trusted categorization.[29] For example, a tunnel set up between two hosts with Generic Routing Encapsulation (GRE) is a virtual private network but is neither secure nor trusted.[30][31]
Native plaintext tunneling protocols include Layer 2 Tunneling Protocol (L2TP) when it is set up without IPsec and Point-to-Point Tunneling Protocol (PPTP) or Microsoft Point-to-Point Encryption (MPPE).[32]
From a security standpoint, a VPN must either trust the underlying delivery network or enforce security with a mechanism in the VPN itself. Unless the trusted delivery network runs among physically secure sites only, both trusted and secure models need an authentication mechanism for users to gain access to the VPN.[citation needed]
Mobile virtual private networks are used in settings where an endpoint of the VPN is not fixed to a single IP address, but instead roams across various networks such as data networks from cellular carriers or between multiple Wi-Fi access points without dropping the secure VPN session or losing application sessions.[37] Mobile VPNs are widely used in public safety where they give law-enforcement officers access to applications such as computer-assisted dispatch and criminal databases,[38] and in other organizations with similar requirements such as field service management and healthcare.[39][need quotation to verify]
A limitation of traditional VPNs is that they are point-to-point connections and do not tend to support broadcast domains; therefore, communication, software, and networking, which are based on layer 2 and broadcast packets, such as NetBIOS used in Windows networking, may not be fully supported as on a local area network. Variants on VPN such as Virtual Private LAN Service (VPLS) and layer 2 tunneling protocols are designed to overcome this limitation.[40]
A VPN, which stands for virtual private network, establishes a digital connection between your computer and a remote server owned by a VPN provider, creating a point-to-point tunnel that encrypts your personal data, masks your IP address, and lets you sidestep website blocks and firewalls on the internet. This ensures that your online experiences are private, protected, and more secure.
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