The supernode can be configured to assign addresses from a different network range: -d 10.0.0.0-10.255.0.0/16 would the supernode make use of the complete 10.0.0.0 class A range but handle /16 -sized sub-networks. Also, named communities could be pre-assigned certain sub-networks, please see the explanatory comments in the community.list file. Failure to disable supernode functions may result in network activity beyond the incidental personal use provisions of the Electronic Communications Policy, and supernode traffic may significantly degrade computer performance. Use of Skype on all other platforms, including Mac OS-X and Linux, is allowed. Suitable operating system. Some operating systems handle large numbers of sockets better than others. Linux, Windows 2000/NT/XP, and Mac OS/X will typically make better ultrapeers than Windows 95/98/ME or Mac Classic. Sufficient bandwidth. We recommend at least 15KB/s downstream and 10KB/s upstream bandwidth. An out of the box Sumcoin Super-Node for Raspberry Pi made for running a GB ATM's or other Node services. Running your own Sumcoin Node adds security as an ATM Operator. Jun 18, 2008 Supernodes are chosen dynamically by the Skype system, and they engender varying degrees of concern and irritation from network administrators. (Skype 3 for Windows has a checkbox to disable becoming a supernode; the current Mac release, 2.7, does not.).
We will explain the theoretical bases of what a node and a supernode are. So that blockchain projects have created the same, how can we participate and what are their tasks within the blockchain network in which they are executed.
What is a Node?
A node in the context of the blockchain, usually refers to a computer that has downloaded the software of the cryptocurrency in question (Bitcoin, Ethereum, Monero, among others) to participate in the network between peers.
The cryptocurrency blockchain is structured as a network architecture between peers (peer-to-peer or P2P). The term peer-to-peer or P2P means that the computers that participate in the network are equal to each other. The term is not new, because making a bit of history, the first massive use of P2P networks was made by the music file sharing network, Napster.
While the Napster network was not at all complex (just a file sharing protocol), comparing it with the blockchain networks of now, its basic principles are the same. In that sense, the oldest P2P network, which most resembles the work of the current blockchains, is the SETI @ HOME network. SETI @ HOME is a computer network, created by SETI to analyze the data of radio telescopes located throughout the world, for the analysis of data from them, in the search for intelligent life in the galaxy. People can participate in this network, just downloading the software from its official website and executing it.
In this way, it is configured that in P2P networks, each computer that participates in the network receives the name of node. In the network, all nodes share the responsibility to provide network services. This is because the interconnection of the network nodes, is what allows the operation of the same.
So in this way, the term blockchain network refers to the set of nodes that execute the P2P protocol of a given blockchain. The network in its entirety orchestrates and coordinates in a completely federated, decentralized and distributed way, the actions that each user does within the network. This implies that this network of computers throughout the world constantly retransmits and transmits new transactions to each other. Each computer in this network is a node that has downloaded the complete blockchain. With this the network becomes redundant, and the work together makes it scalable with respect to its expansion.
Due to the decentralization of the blockchain, anyone can participate within them. Simply download the node software from them and execute it. Usually, the main wallets of each project allow this functionality. Initially, the network begins the pareo of the blockchain, until reaching the point of synchronization with the network. At that moment, the node begins its full operation, not only allowing and verifying transactions but also supporting an image of the global blockchain. Normally nodes can perform the following functions: routing, blockchain database, mining and wallet or purse services.
The nodes are the individual parts of the largest data structure that is a blockchain. As node owners voluntarily contribute their computing resources to store and validate transactions, they have the opportunity to charge transaction fees and earn a reward in the underlying cryptocurrency for doing so.
The processing of these transactions may require large amounts of computing and processing capacity, which means that the average capabilities of a computer are inadequate. In general, professional miners tend to invest in extremely powerful computing devices known as CPUs (central processing units) or GPUs (graphics processing units) to keep up with the demand for processing power that is required to validate transactions and, as such, earn the rewards that come with doing it.
A node can be a communication endpoint or a redistribution point of communication, linking to other nodes. Each node in the network is considered equal, however, certain nodes have different roles in the way they support the network. For example, not all nodes will store a complete copy of a chain of blocks or validate transactions.
A complete node downloads a complete copy of a chain of blocks and checks the new transactions that arise based on the consensus protocol used by that particular cryptocurrency or utility token. All nodes use the same consensus protocol to remain compatible with each other. It is the nodes in the network that confirm and validate the transactions, placing them in blocks. The nodes always come to their own conclusion about whether a transaction is valid and should be added to a block with other transactions, regardless of how other nodes act.
What are the basic tasks of a node?
When a miner or user by some mechanism of the protocol in question, tries to add a new block of transactions to the blockchain, it transmits the block to all the nodes of the network. On the basis of the legitimacy of the block (validity of the signature and transactions), the nodes can accept or reject the block. When a node accepts a new block of transactions, it saves it and stores it on the rest of the blocks it has already stored. In summary, this is what the nodes do:
They check if a block of transactions is valid and accept or reject it. Store and store transaction blocks (storing the blockchain transaction history). Transmit and extend this transaction history to other nodes that may need to be synchronized with the blockchain (they must be updated in the transaction history).
Classification of Nodes
In blockchain networks, there are traditionally three types of nodes, which provide different functions within the network. These types of nodes are:
Broadcast nodes: they only issue transactions and receive blockchain information, from a third party. They follow what dictates the greatest mining power and are known as light purses, widely used in mobile devices or simply by people who do not want to download the entire blockchain. Complete nodes: when you install a complete node software such as Bitcoin Core, in addition to having the safest wallet, you will be downloading a copy of the blockchain and you will become a node in the Bitcoin network. So you will issue your transactions, propagate the rest of the network and verify that the consensus rules are met. Mining nodes: the miners must necessarily have a copy of the chain of blocks, in addition to operating the software miner they prefer (BTCMiner, CGMiner). These nodes, in addition to mining bitcoins and therefore helping to create new blocks, also issue and propagate transactions.
How safe is a node?
The nodes can be online or offline. The online nodes are receiving, saving and transmitting all the last blocks of transactions to and from other nodes, while the nodes without connection do not. When an offline node comes back online, it will first have to catch up with the rest of the blockchain by downloading all the blocks that were added to the blockchain since the node was disconnected. This process is often called synchronization with the blockchain.
Theoretically, a complete blockchain can be executed in a single node, but as it would be stored in a single device, it would be extremely vulnerable to situations like power outages, hackers or systemic failures. The more full nodes are running in a blockchain, the better their recovery capacity in the face of such catastrophes. When the data of the blockchain is distributed in so many devices, it will be very difficult for a corrupt entity to erase all this data at once. Even if a large number of nodes suddenly fall and become inaccessible due to a global crisis, theoretically a single node can keep a whole chain of blocks operational. And even if all the nodes are disconnected, only one node with the complete blockchain history is needed to get back online and make all the data accessible again.
In addition to the security that the nodes can add to the network, for its large number. The nodes are also vulnerable to computer attacks, which may alter their functioning. For example, a pirate can violate the security of the software in question, and without altering the data of the blockchain, it can redirect the profits of said nodes to addresses different from those programmed by their owners. Stealing address attacks are the types of attacks most common to this type of software, and that is why developers recommend using updated versions of their blockchain software.
Some of these security flaws can be easily solved, using a bit of common sense towards computer security, or using software tools that create security mechanisms to isolate blockchain software from the rest of our computer systems. Among these measures can be mentioned:
Use official or developer software with a long and proven track record. Safeguard private keys, mnemonic keys, and any other privileged information of our activity in the blockchain. Use computers or electronic equipment solely and exclusively for our mining activities. Use sandboxing software to isolate software applications from the rest of our system. Use MAC (Mandatory Access Control) systems or system privileges that allow us to run our blockchain software with the minimum access permissions to our OS and other system APIs (this isolation is greater than a sandboxing).
What are the Master Nodes (Masternodes)?
The master nodes or masters, are unique characteristics of some current blockchains. Masternodes are usually much more equipped than normal nodes. In addition to validating, saving and transmitting transactions, sometimes masternodes also facilitate other events in the chain of blocks depending on their nature, such as voting events, execution of protocol operations and compliance with the laws of the block chain. correspondent. Masternodes are generally always online (24/7) and provide much more memory than normal nodes. Because the accommodation of a masternode usually requires many more resources (electricity, uptime, maintenance, storage space, memory), the accommodation in general provides a payment in the form of interest.
However, given the peculiarity of the masternodes, not everyone can run one. The power to control a masternode can be abused, and therefore requires the host to deposit a minimum (often quite large) amount of cryptocurrencies as collateral. This guarantee is taken as a hostage when the masternode host violates the rules of the block chain. The interest rate received by a masternode host is calculated on your security deposit. Of this money retained, depends the gain of the owner of the masternode, which is measured by a percentage of all transactions and operations handled by the set of masternodes in question. Projects such as DASH and Ethereum have the use and creation of masternodes in their structure.
Also published on Medium.
I pose the question in the headline based on the early feedback from readers of my new book, “Take Control of Back to My Mac,” which covers using Mac OS X 10.5 Leopard plus the .Mac service (soon to be called MobileMe) for remotely accessing files on and remotely controlling the screens of Macs you manage or own.
The trouble with Back to My Mac, in comparison with Skype and LogMeIn, is that Back to My Mac requires a publicly routable IP address on either a computer that’s to be reachable or a router to which one or more computers with Back to My Mac are connected.
The question I’ve heard from multiple readers is, “I’m not a network engineer. Galactic petting zoo!!! mac os. How do I figure out if I have such an IP address?”
There’s a short non-answer and a long answer. The short non-answer is that I can’t give you a good short answer because the Internet is broken. The current system of public and private networks, designed in part to get around a shortage in the current IP addressing system, doesn’t allow easy end-to-end connections. For the long answer, read on. (I expand on the short non-answer in the last section, too.)
Public IP versus Private IP — Let me back up to explain what a public IP address really is. The Internet is Balkanized through something called Network Address Translation (NAT), which allows a single public IP address that’s reachable, or routable, from any other computer on the Internet to act as a kind of proxy for 1, 1,000, or 1,000,000 private IP addresses. A gateway mediates traffic between the public address and the private one. (You can read more about NAT in “Punch Through NAT with Port Map’s Port Forwarding,” 2008-04-16.)
If a computer on which you want to enable Back to My Mac has a public IP address – as do some computers in my office network – then Back to My Mac works without a hitch. It allows any other computers that you log into with your .Mac account name and password, and on which you enable Back to My Mac in the .Mac system preference pane, to access that publicly addressed computer. (If you have a public IP that’s assigned to individual computers, you probably already know that you do, because you’re likely paying your ISP more for that privilege.)
Where a computer is on a private network, using a range of addresses that can be reached only through a router, Back to My Mac has to perform a NAT end-run using one of two widely available protocols that let a privately addressed computer punch through the NAT gateway with the router’s assistance. Those protocols are NAT-PMP (NAT Port Mapping Protocol), an open standard used exclusively by Apple, and UPnP (Universal Plug and Play), another standard used widely by other routers and supported by Apple and Microsoft for various services.
By subverting NAT, these two protocols enable a router that has a public IP address to make services on private computers available publicly. It’s a secondary problem to let other computers know precisely which ports – a kind of numbered cubbyhole on an IP address, in this case the address of the router – are used by whatever game, remote access service, IP phone, or other software that has engaged NAT-PMP or UPnP.
Apple plays nice with networks by using these two protocols. LogMeIn, Skype, and other remote connection and voice-over-IP programs use their own techniques to link computers that can’t be reached via public IP addresses. Skype, for instance, uses “supernodes,” which are computers with a logged-in Skype user, a high bandwidth connection, and a reachable address. Supernodes are chosen dynamically by the Skype system, and they engender varying degrees of concern and irritation from network administrators. (Skype 3 for Windows has a checkbox to disable becoming a supernode; the current Mac release, 2.7, does not.)
Your Network’s Layout — The next piece in figuring out whether you have a publicly reachable IP is looking at how your broadband network is set up. Most of us at home have a cable, DSL, or fiber modem that connects to some incoming wire, and has one or more local Ethernet jacks, and optionally Wi-Fi.
Some broadband modems act as full-fledged routers: they assign private addresses to networked computers and let you configure firewall and other network settings. Others act like bridges: they enable the ISP to assign you an address (which can be public or private, and either dynamic or static) and relay traffic from the ISP’s network to yours.
With a modem that acts as a router, you may be unable to use Back to My Mac because that modem controls access to the network. If the modem doesn’t support or allow you to enable UPnP, you’re stuck using manual port mapping (if supported), which lets you set up only one computer to be reachable via Back to My Mac. (I cover the ugly details of port mapping in my book. It gets rather involved.)
I have this kind of modem in my home, for Qwest DSL service, and I’m stuck because it’s made by 2Wire. Although Qwest gives me a public IP address, 2Wire does not offer UPnP support in any of its modems; its customers are ISPs, typically DSL providers who don’t wish to allow users to make public services from networked computers available, largely due to security and control reasons.
A theoretical malicious program could use UPnP or NAT-PMP to open a tunnel to itself from other agents in the outside world, and become, for instance, a mail server delivering spam or any of a number of other activities. So there’s some justification for disabling UPnP, but it should be left up to the user, since viruses can work without enabling direct port mapping.
With the second kind of modem, the one that bridges a network, you can connect your AirPort Extreme Base Station or other gateway to the broadband modem, obtain what’s typically a publicly reachable IP address, enable the automatic port mapping option (NAT-PMP or UPnP), and then Bob’s your uncle: Back to My Mac typically works. Many broadband networks are set up this way, and it’s one of the best cases in which to use Back to My Mac.
Now, how can you tell which type of modem you have, and how can you tell whether you have a public IP address? Let’s get into that next. Naomi mac os.
Reach Out and IP Someone — We start with the broadband modem. Can you view your modem’s configuration by connecting to it over your local network via a Web browser? If not, then you find yourself in one of two situations:
- The modem is a bridge, and you still need to determine whether or not devices you plug into it obtain or can be assigned a public IP address.
- Your modem has a configuration locked down by your ISP, and you can neither enable UPnP if available nor use manual port mapping if UPnP is unavailable. In this second case, you’re out of luck with Back to My Mac.
If you can connect to your broadband modem via a Web browser, do so (this may require a password, which may require a call to your ISP), and see what the summary screen or status screen tells you about the modem’s Wide Area Network (WAN) connection – the modem’s connection back to the ISP’s network.
That screen should provide you the address the modem is using. In some cases, you’ll see just one number; with my Qwest modem, I see both a private address in Qwest’s network and a separate public address to which Qwest connects my modem, both of them clearly labeled.
You can tell whether this WAN address is public or private by looking at its first few numbers. Current IP addresses – using the ancient IPv4 numbering system – have four numbers separated by dots, like 10.0.0.1. If the WAN port’s IP address starts with 192.168 or 10., or begins with 172. followed by the numbers 16 to 31, it’s a private address. (Examples: 192.168.0.1, 10.0.0.1, 172.16.5.1.) You’ll need to contact your ISP to see if you can get a public address.
If the number doesn’t fit any of those patterns, it should be a public address, and should be generally reachable.
Now, if you can’t connect to your broadband modem from the local network or if you want to ensure the address you’re looking at for the WAN port is truly public, you can use a Web site that tries to tell you your current IP address; WhatIsMyIPAddress.com is one of many examples. These sites tell you what they believe the address is of the router or computer that sent the request. However, if your network is nested in one or more layers of NAT, the page shows the IP address of an ISP’s router.
Visit that link. Does it match the configuration screen (if any) of the broadband modem? If so, you’re almost certainly set to go.
If not, or if that doesn’t apply, you can try at least one technique to see if the router is reachable: the command-line tool ping. Make a note of the address from the Web page and leave your home or office. Using Mac OS X from another network, launch Terminal (in Applications/Utilities); under Windows, launch the Command Prompt program in the Applications folder. At the prompt type:
ping -c 10 address
replacing address with the IP address that you copied. Do you see a few lines in response in the Terminal like this one?
64 bytes from 34.33.111.253: icmp_seq=0 ttl=127 time=10.564 ms
That means the modem is responding to an “are you alive” request over the Internet, and is likely reachable.
Let’s put this all together.
Back into Back to My Mac — If, in any of the cases above, you believe or know that you have a public IP address connected to a modem or router that can use NAT-PMP or UPnP, or that you have used manual port mapping to enable access to one computer via Back to My Mac, turn on Back to My Mac and see if you can reach the computer from outside your local network. (You can’t properly test Back to My Mac with two computers on the same local network, since Leopard doesn’t offer any visual indication to show whether a computer in the Shared list in the Finder sidebar is available via Bonjour over the local network or via Back to My Mac over the Internet.)
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If that doesn’t work, or you determine you don’t have a public IP address, there’s nothing more you can do on your own; it’s time to call your ISP if you want any hope of making Back to My Mac work.
To recap, Back to My Mac should work on a network in which one of these conditions is met:
- Your ISP has assigned your modem a public IP address and it supports either UPnP or manual port mapping.
- Your ISP bridges their network across the modem, providing a public IP address for your router, which supports NAT-PMP, UPnP, or manual port mapping.
Back to My Mac won’t work on a network in which either of these conditions are true: Chernobyl 8-bit mac os.
- Your ISP doesn’t provide a public IP address to your modem or your router.
- You can’t configure UPnP, NAT-PMP, or manual port mapping on your modem or router.
If your network should allow proper Back to My Mac functioning, and you still get a yellow dot (in Mac OS X 10.5.3) in the .Mac preference pane’s Back to My Mac view (see “Back to My Mac Communicates Faults in 10.5.3,” 2008-05-29) then you either need to read my book, or try an alternative like LogMeIn Free for Mac or Timbuktu plus Skype. I have advised many TidBITS readers to try these alternatives because their networks simply won’t work with Back to My Mac.
The Future with IPv6 — As I said at the outset, the Internet is broken. IPv4 addresses are in short supply and running out. But take heart: IPv6 is IPv4’s replacement, has vastly more potential addresses (4 billion to the fourth power, versus 4 billion), and is designed and implemented in a way that will restore much of the end-to-end principle of the Internet. This introduces more security concerns, but also makes it much more likely that network services will just work.
IPv6 isn’t a simple migration; every single device on the Internet must support the new protocol and deal with the long, perhaps eternal, transition from IPv4. Mac OS X and Windows have supported IPv6 for years, but DSL and cable modems have lagged even as other components of broadband networks have been upgraded. Comcast, for instance, uses IPv6 for its vast internal routing network, because they simply couldn’t obtain enough IPv4 numbers for their needs. (You can read more about this in a recent article I wrote for the Economist, “Your Number’s Up.”)
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I bring up IPv6 not to complicate your understanding, but because Apple has enabled IPv6 in two key places that have to do with your network and Back to My Mac. IPv6 can be tunneled over existing IPv4 networks, which means that data addresses using the new scheme can be wrapped within packages addressed with the old.
In fact, Back to My Mac takes advantage of this. Connections made with Back to My Mac use tunnels of IPv6 to transport data packets, which are wrapped in strong encryption. Back to My Mac essentially creates two IPv6 end points, one on each computer connected via Back to My Mac. Ultimately, this should enable better connectivity using more services – perhaps allowing third-party Mac developers to wire in their own services.
The other key point is that Apple has enabled IPv6 in their Draft N routers: any Wi-Fi-enabled base station released in 2007 or 2008, including the revised AirPort Express Base Station. Apple isn’t supporting just IPv6 addressing – which would be like letting postal carriers know that a house has an old house number and a new house number – but is also allowing tunneling IPv6 from the local network out to IPv6 gateways on the Internet.
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These gateways, run at no cost to the user, let you connect native IPv6 networks, such as those run by Apple’s recent AirPort base stations, to each other using the current Internet without any need for changes by your ISP. Over time, experts and network operators have told me, IPv6 connections will expand further into the backbone of the Internet, and eventually IPv4 will primarily be tunneled inside of IPv6, instead of the reverse.
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With IPv6, the idea of a public or private IP address more or less goes away, and the necessity of building and using a service like Back to My Mac drops a bit, too. You’d still want the security of Back to My Mac’s authentication (proving your identity) and encryption (securing the connection), but you’ll no longer need to muck about with the question of public and private IP addresses.