Information AboutHamachi |
| CATEGORIES ABOUT HAMACHI | |
| freeware | |
| network-related software | |
Hamachi is a Zero-configuration Virtual Private Networking (VPN) Freeware application. It is the first VPN application capable of establishing direct links between computers that are both NAT ed without requiring NAT reconfiguration. Currently available as a beta for Microsoft Windows and Linux . Mac OS X version is in development, with a console version available . HOW HAMACHI WORKS Hamachi installs a virtual Network Interface on a computer. Hamachi then Tunnels all IP and IPX traffic sent to this interface over a specially initiated real UDP connection between hosts. It is able to benefit from the existing routing functions in the computer's TCP/IP Stack . Hamachi uses a 3rd party "mediation server" to Bootstrap the connections between hosts on a Hamachi network. It is hypothesized that Hamachi establishes the connection between two NATed hosts by directing them to initiate network connections to each other at the exact same time. The mediation server knows the public NATed IP addresses of the two hosts. It tells each of the hosts to connect to each other at the same time to their respective public IP addresses. The NAT devices open ports on the public sides of their routers to accept return traffic. The NAT devices leave the ports open based on idle timers. This then allows the two hosts to continue the connection on their own. As long as Hamachi sends periodic traffic, also known as keep alive traffic, the ports will remain open on the NAT devices. Normally a NAT would silently drop unsolicited traffic, thereby preventing a connection. However since the network traffic was initiated from both hosts at the same time the NAT devices are willing to accept the traffic and forward it on to the respective hosts. This process does not work on all NAT devices. About 5% of NAT devices do not support Hamachi. Hamachi provides an alternative configuration called the "Magic Option" that requires explicitly setting a port forward on the unsupported NAT device. When a user named G12 brought up UDP Hole Punching on the Hamachi forums one of Hamachi’s developers, apankrat, responded by saying, "... There is a possiblity that the mediation server accepts connections from both clients and so by knowing which tcp Port number was used for outbound traffic on the other side the known entry port to direct to the right machine through the NAT is known. Since Hamachi is not Open Source Software and no Patent s seemed to have been filed, the Source Code is not available for review so its actual function is secret. No open source projects are known to exist that replicate Hamachi's functionality. Port translation It must also be able to determine the return port that connections are being translated to on the NAT device. The mediation server might assume that return Port numbers on the NAT device are assigned in numerical order, and thus assume that the port number the NAT device will use will be the port number subsequent to a port number used to connect to the mediation server. Relayed tunneling Apparently Hamachi 1.0 will offer a paid service called relayed tunneling {Link without Title} for those few users that are unable to configure an unsupported NAT device. In addition, the Hamachi 1.0 beta available now from {Link without Title} has this feature already, in the form of "low-bandwidth relays". The premium version will (when it is completed) offer a high-bandwidth version of this service. However, if you have control over the NAT firewall of at least one end, you should port-forward the appropriate UDP port (set in the Magic Option setting) to the computer, thus usually avoiding the need for a relay at all. USES Hamachi's ability to penetrate NAT and proxy servers has meant that it has become a popular way to access one LAN from another one (eg. your home LAN from school or work). The most popular use of Hamachi has been for gaming. Most games will see the Hamachi connection as a Local Area Network, and so games hosted by any of your peers on the Hamachi network will appear in the 'LAN' category for most games. This use has become especially popular because it avoids the latency issues that other connections can have. Hamachi is also frequently used in conjunction with Windows' Remote Desktop and Virtual Network Computing (VNC) sessions, in which case it provides both communication and security services to these applications. PREMIUM (PAY) SERVICE Having a premium account unlocks a number of features both on the server side and in the client itself. These include advanced network management, an ability to natively run Hamachi as service, an ability to join 'full' networks, an option to have unencrypted networks (improves performance), an option for network-wide chat, an ability to use relays for talking with 'unreachable' peers, etc A comparison matrix of Basic vs Premium is available {Link without Title} . Currently, not all features are implemented for premium. However, the 1.0 beta mentioned above has support for a trial premium setup using the trial key (TRIAL). SEE ALSO
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