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HTTP Tunnel
HTTP tunneling is used to create a network link between two computers in conditions of restricted network connectivity including firewalls, NATs and ACLs, among other restrictions. The tunnel is created by an intermediary called a proxy server which is usually located in a DMZ. Tunneling can also allow communication using a protocol that normally wouldn’t be supported on the restricted network. HTTP CONNECT method The most common form of HTTP tunneling is the standardized HTTP CONNECT method. In this mechanism, the client asks an HTTP proxy server to forward the TCP connection to the desired destination. The server then proceeds to make the connection on behalf of the client. Once the connection has been established by the server, the proxy server continues to proxy the TCP stream to and from the client. Only the initial connection request is HTTP - after that, the server simply proxies the established TCP connection. This mechanism is how a client behind an HTTP proxy can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Firewall (computing)
In computing, a firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. A firewall typically establishes a barrier between a trusted network and an untrusted network, such as the Internet. History The term ''firewall'' originally referred to a wall intended to confine a fire within a line of adjacent buildings. Later uses refer to similar structures, such as the metal sheet separating the engine compartment of a vehicle or aircraft from the passenger compartment. The term was applied in the late 1980s to network technology that emerged when the Internet was fairly new in terms of its global use and connectivity. The predecessors to firewalls for network security were routers used in the late 1980s. Because they already segregated networks, routers could apply filtering to packets crossing them. Before it was used in real-life computing, the term appeared in the 1983 computer-hacking movie ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BOSH (protocol)
Bidirectional-streams Over Synchronous HTTP (BOSH) is a transport protocol that emulates a bidirectional stream between two entities (such as a client and a server) by using multiple synchronous HTTP request/response pairs without requiring the use of polling or asynchronous chunking. For applications that require both "push" and "pull" communications, BOSH is significantly more bandwidth-efficient and responsive than most other bidirectional HTTP-based transport protocols and AJAX. BOSH achieves this by avoiding HTTP polling, yet it does so without resorting to chunked HTTP responses as is done in the technique known as Comet. To date, BOSH has been used mainly as a transport for traffic exchanged between Jabber/XMPP clients and servers (e.g., to facilitate connections from web clients and from mobile clients on intermittent networks). For "push", a BOSH client starts an HTTP request, but the server postpones sending a reply until it has data to send. After receiving a reply, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunneling Protocols
In computer networks, a tunneling protocol is a communication protocol which allows for the movement of data from one network to another. It involves allowing private network communications to be sent across a public network (such as the Internet) through a process called encapsulation. Because tunneling involves repackaging the traffic data into a different form, perhaps with encryption as standard, it can hide the nature of the traffic that is run through a tunnel. The tunneling protocol works by using the data portion of a packet (the payload) to carry the packets that actually provide the service. Tunneling uses a layered protocol model such as those of the OSI or TCP/IP protocol suite, but usually violates the layering when using the payload to carry a service not normally provided by the network. Typically, the delivery protocol operates at an equal or higher level in the layered model than the payload protocol. Uses A tunneling protocol may, for example, allow a foreig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypertext Transfer Protocol
The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access, for example by a mouse click or by tapping the screen in a web browser. Development of HTTP was initiated by Tim Berners-Lee at CERN in 1989 and summarized in a simple document describing the behavior of a client and a server using the first HTTP protocol version that was named 0.9. That first version of HTTP protocol soon evolved into a more elaborated version that was the first draft toward a far future version 1.0. Development of early HTTP Requests for Comments (RFCs) started a few years later and it was a coordinated effort by the Internet Engineering Task Force (IETF) and the World Wide Web Consortium (W3C), with work later moving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Virtualization Using Generic Routing Encapsulation
Network Virtualization using Generic Routing Encapsulation (NVGRE) is a network virtualization technology that attempts to alleviate the scalability problems associated with large cloud computing deployments. It uses Generic Routing Encapsulation (GRE) to tunnel layer 2 packets over layer 3 networks. Its principal backer is Microsoft. See also * Virtual Extensible LAN (VXLAN), a similar competing specification * Generic Networking Virtualization Encapsulation (GENEVE), an industry effort to unify both VXLAN and NVGRE technologies * Generic Routing Encapsulation Generic Routing Encapsulation (GRE) is a tunneling protocol developed by Cisco Systems that can encapsulate a wide variety of network layer protocols inside virtual point-to-point links or point-to-multipoint links over an Internet Protocol netw ..., GRE for transporting L3 packets. References External links NVGRE Overview November 19, 2012, by Joe Onisick Tunneling protocols {{Compu-network-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Extensible LAN
Virtual Extensible LAN (VXLAN) is a network virtualization technology that attempts to address the scalability problems associated with large cloud computing deployments. It uses a VLAN-like encapsulation technique to encapsulate OSI layer 2 Ethernet frames within layer 4 UDP datagrams, using 4789 as the default IANA-assigned destination UDP port number. VXLAN endpoints, which terminate VXLAN tunnels and may be either virtual or physical switch ports, are known as VXLAN tunnel endpoints (VTEPs). VXLAN is an evolution of efforts to standardize on an overlay encapsulation protocol. Compared to VLAN which provides limited number of layer-2 VLANs (typically using 12-bit VLAN ID), VXLAN increases scalability up to 16 million logical networks (with 24-bit VNID) and allows for layer-2 adjacency across IP networks. Multicast or unicast with head-end replication (HER) is used to flood Broadcast, unknown-unicast and multicast traffic. The VXLAN specification was originally created by VMwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Private Network
A virtual private network (VPN) extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. The benefits of a VPN include increases in functionality, security, and management of the private network. It provides access to resources that are inaccessible on the public network and is typically used for remote workers. Encryption is common, although not an inherent part of a VPN connection. A VPN is created by establishing a virtual point-to-point connection through the use of dedicated circuits or with tunneling protocols over existing networks. A VPN available from the public Internet can provide some of the benefits of a wide area network (WAN). From a user perspective, the resources available within the private network can be accessed remotely. Types Virtual private networks may be classified into several categories: ;Remote acce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudo-wire
In computer networking and telecommunications, a pseudowire (or pseudo-wire) is an emulation of a point-to-point connection over a packet-switched network (PSN). The pseudowire emulates the operation of a "transparent wire" carrying the service, but it is realized that this emulation will rarely be perfect. The service being carried over the "wire" may be Asynchronous Transfer Mode (ATM), Frame Relay, Ethernet or time-division multiplexing (TDM) while the packet network may be Multi-protocol Label Switching (MPLS), Internet Protocol (IPv4 or IPv6), or Layer 2 Tunneling Protocol Version 3 (L2TPv3). The first pseudowire specifications were the Martini draft for ATM pseudowires, and the TDMoIP draft for transport of E1/T1 over IP. In 2001, the Internet Engineering Task Force (IETF) set up the PWE3 working group, which was chartered to develop an architecture for service provider edge-to-edge pseudowires, and service-specific documents detailing the encapsulation techniques. Othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ICMP Tunnel
An ICMP tunnel establishes a covert connection between two remote computers (a client and proxy), using ICMP echo requests and reply packets. An example of this technique is tunneling complete TCP traffic over ping requests and replies. Technical details ICMP tunneling works by injecting arbitrary data into an echo packet sent to a remote computer. The remote computer replies in the same manner, injecting an answer into another ICMP packet and sending it back. The client performs all communication using ICMP echo request packets, while the proxy uses echo reply packets. In theory, it is possible to have the proxy use echo request packets (which makes implementation much easier), but these packets are not necessarily forwarded to the client, as the client could be behind a translated address ( NAT). This bidirectional data flow can be abstracted with an ordinary serial line. ICMP tunneling is possible becausRFC 792 which defines the structure of ICMP packets, allows for an arb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whitelist
A whitelist, allowlist, or passlist is a mechanism which explicitly allows some identified entities to access a particular privilege, service, mobility, or recognition i.e. it is a list of things allowed when everything is denied by default. It is the opposite of a blacklist, which is a list of things denied when everything is allowed by default. Email whitelists Spam filters often include the ability to "whitelist" certain sender IP addresses, email addresses or domain names to protect their email from being rejected or sent to a junk mail folder. These can be manually maintained by the user or system administrator - but can also refer to externally maintained whitelist services. Non-commercial whitelists Non-commercial whitelists are operated by various non-profit organisations, ISPs, and others interested in blocking spam. Rather than paying fees, the sender must pass a series of tests; for example, their email server must not be an open relay and have a static IP address. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
