Linux Cache

https://developers.ripple.com/xrp-ledger-overview.html

The XRP Ledger is a decentralized cryptographic ledger powered by a network of peer-to-peer servers. The XRP Ledger is the home of XRP, a digital asset designed to bridge the many different currencies in use worldwide. Ripple stewards the development of the XRP Ledger, and advances XRP as a key contribution to the Internet of Value: a world in which money moves the way information does today.
The Digital Asset for Payments

XRP is a digital asset native to the XRP Ledger. Anyone with a cryptographic key and an internet connection can receive, hold, and send XRP to anyone else. XRP’s creators have developed it to be a desirable bridge currency that can facilitate trades in any other currency. XRP has many properties which make it an appealing asset for many other use cases, too:

Censorship-Resistant Transaction Processing: No single party decides which XRP transactions succeed or fail, and no one can “roll back” a transaction after it completes. As long as those who choose to participate in the network keep it healthy, they can send and receive XRP in seconds.
Fast, Efficient Consensus Algorithm: The XRP Ledger’s consensus algorithm settles transactions in 4 to 5 seconds, processing at a throughput of up to 1500 transactions per second. These properties put XRP at least an order of magnitude ahead of other top digital assets.
Finite XRP Supply: When the XRP Ledger began, 100 billion XRP were created, and no more XRP will ever be created. (Each XRP is subdivisible down to 6 decimal places, for a grand total of 100 quintillion drops of XRP.) The available supply of XRP decreases slowly over time as small amounts are destroyed to pay transaction costs.
Responsible Software Governance: A team of full-time, world-class developers at Ripple maintain and continually improve the XRP Ledger’s underlying software. Ripple acts as a steward for the technology and an advocate for its interests, and builds constructive relationships with governments and financial institutions worldwide.
Secure, Adaptable Cryptography: The XRP Ledger relies on industry standard digital signature systems like ECDSA (the same scheme used by Bitcoin) but also supports modern, efficient algorithms like Ed25519. The extensible nature of the XRP Ledger’s software makes it possible to add and disable algorithms as the state of the art in cryptography advances.
Modern Features for Smart Contracts: Features like Escrow, Checks, and Payment Channels support cutting-edge financial applications including the Interledger Protocol. This toolbox of advanced features comes with safety features like a process for amending the network and separate checks against invariant constraints.
On-Ledger Decentralized Exchange: In addition to all the features that make XRP useful on its own, the XRP Ledger also has a fully-functional accounting system for tracking and trading obligations denominated in any way users want, and an exchange built into the protocol. The XRP Ledger can settle long, cross-currency payment paths and exchanges of multiple currencies in atomic transactions, bridging gaps of trust with XRP.

Censorship-Resistant Transaction Processing

XRP is part of a new class of money which includes Bitcoin and other cryptocurrencies:

These Decentralized digital assets exist in computer systems without a central administrator. As long as the system is sufficiently decentralized, no one can roll back transactions, freeze balances, or block someone from using a decentralized digital asset. These assets are natively digital, so they can be used online across any distance.

This combines qualities of physical and centralized digital money. Prior to the invention of Bitcoin in 2009, all currencies could be divided into those two categories:

Physical coins and paper money, which individuals can use to do business without going through a central party. As physical objects, they cannot be used online, and doing business long-distance is slow and inconvenient.
Centralized digital currencies, which need an administrator to confirm transactions. The administrator also has the power to censor or roll back transactions, or disallow some individuals from using the digital currency. If the operator of a digital currency decides someone has violated its terms of service, it can freeze or even confiscate that person’s money. However, as digital balances, these currencies can be used online and are convenient across long distances.

Note:
Users of the XRP Ledger can freeze non-XRP currencies issued in the XRP Ledger. For more information, see the Freeze documentation.

The XRP Ledger’s system of trusted validators uses a small amount of human interaction to achieve better distribution of authority than other decentralized systems. Fully-automated systems for reaching consensus from an unknown set of participants are vulnerable to concentrations of voting power. For example, Bitcoin mining is disproportionately concentrated in places with cheap electricity. As Ripple curates a list of distinct validators operated by different entities in different jurisdictions, the XRP Ledger can become more resistant to censorship and outside pressures than proof-of-work mining. For more information on Ripple’s plan to decentralize the recommended set of validators, see the Decentralization Strategy Update.
Fast, Efficient Consensus Algorithm

The XRP Ledger’s biggest difference from most cryptocurrencies is that it uses a unique consensus algorithm that does not require the time and energy of “mining”, the way Bitcoin, Ethereum, and almost all other such systems do. Instead of “proof of work” or even “proof of stake”, The XRP Ledger’s consensus algorithm uses a system where every participant has an overlapping set of “trusted validators” and those trusted validators efficiently agree on which transactions happen in what order. As of early 2018, the amount of electricity the Bitcoin network uses per transaction is more than a family home in the USA uses in an entire day, and confirming the transaction takes hours. A single XRP transaction uses a negligible amount of electricity, and takes 4 or 5 seconds to confirm.

Furthermore, each new “ledger version” in the XRP Ledger (the equivalent of a “block”) contains the full current state of all balances, so a server can synchronize with the network in minutes instead of spending hours downloading and re-processing the full transaction history.

For more information on how the XRP Ledger’s consensus algorithm works, see The XRP Ledger Consensus Process. For background on why the XRP Ledger uses this consensus algorithm, see Consensus Principles and Rules.
Finite XRP Supply

Alongside war and political turmoil, hyperinflation is one of the leading causes of death for currencies. While the decentralized system of validators provides XRP with some resistance to political factors, the rules of the XRP Ledger provide a simpler solution to hyperinflation: the total supply of XRP is finite. Without a mechanism to create more, it becomes much less likely that XRP could suffer hyperinflation.

The supply of XRP available to the general public does change due to a few factors:

Sending transactions in the XRP Ledger destroys a small amount of XRP. Senders choose how much to destroy, with certain minimums based on the expected work of processing the transaction and how busy the network is. If the network is busy, potential transactions that promise to destroy more XRP can cut in front of the transaction queue. This is an anti-spam measure to make it prohibitively expensive to DDoS the XRP Ledger network. For more information, see Transaction Cost.
Each account in the XRP Ledger must hold a small amount of XRP in reserve. This is an anti-spam measure to disincentivize making the ledger data occupy too much space. XRP Ledger validators can vote to change the amount of XRP required as a reserve, to compensate for changes in XRP’s real-world value. (The last time this happened was in December 2013, when the reserve requirement decreased from 50 XRP to 20 XRP.) If the reserve requirement decreases, XRP that was previously locked up by the reserve becomes available again.
Ripple (the company) holds a large reserve of XRP in escrow. At the start of each month, 1 billion XRP is released from escrow for Ripple to use. (Ripple uses XRP to incentivize growth in the XRP Ledger ecosystem and sells XRP to institutional investors. Ripple also sells XRP programmatically on exchanges, limited to a small percentage of overall exchange volume. Ripple publishes sales figures quarterly in the XRP Markets Report.) At the end of each month, any remaining XRP the company does not sell or give away is stored into escrow for a 54-month period. For more information on Ripple’s escrow policy, see Ripple Escrows 55 Billion XRP for Supply Predictability. For more information on the technical capabilities of the Escrow feature, see Escrow.

Responsible Software Governance

Any piece of software can only be as good as the developers who code and manage it. Ripple employs a team of world-class engineers dedicated full-time to maintaining and improving the XRP Ledger software, especially the core server, rippled. The source code for rippled is available to the public with a permissive open-source license, as are many other parts of the XRP Ledger ecosystem. Ripple engineers follow best practices for software engineering, including:

A famously strict and thorough code review process
Comprehensive code coverage and unit tests
Regularly running automated checks for potential vulnerabilities and memory leaks
Regularly commissioning external reviews by professional organizations

As an entity that is obligated to hold large amounts of XRP for the long term, Ripple has a strong incentive to ensure that XRP is widely used in ways that are legal, sustainable, and constructive. Ripple provides technical support to businesses whose goals align with Ripple’s ideal of an Internet of Value. Ripple also cooperates with legislators and regulators worldwide to guide the implementation of sensible laws governing digital assets and associated businesses.
Secure, Adaptable Cryptography

Cryptography is one of the hardest parts of any distributed system, and a mistake can lead to money stolen by malicious actors anywhere in the world. The XRP Ledger uses industry-standard schemes for signing and verifying transactions, algorithms that have successfully protected hundreds of billions of US dollars’ worth of value for many years. The XRP Ledger also layers multi-signing functionality so you can use multi-factor authorization or split keys across multiple people as a backup, and provides new algorithms with a path to migrate the keys you use if a breakthrough in cryptography makes the old algorithms obsolete.

For more information, see Cryptographic Keys and Multi-Signing.
Modern Features for Smart Contracts

Besides simple value transfer with XRP payments, the XRP Ledger has several advanced features that provide useful functions for building applications that use the Internet of Value to serve previously unknown or impractical needs. Rather than running applications as “smart contracts” in the network itself, the XRP Ledger provides tools for settling contracts, while letting the applications themselves run anywhere, in whatever environment or container is appropriate. This “keep it simple” approach is flexible, scalable, and powerful.

A sample of advanced features in the XRP Ledger:

Payment Channels allow asynchronous balance changes as fast as you can create and validate signatures.
Escrow locks up XRP until a declared time passes or cryptographic condition is met.
DepositAuth lets users decide who can send them money and who can’t.
A Decentralized Exchange lets users trade obligations and XRP on-ledger.
Invariant Checking provides an independent layer of protections against bugs in transaction execution.
Amendments provide smooth upgrades to the existing feature set, so the technology can continue to evolve without fracturing the ecosystem or causing uncertainty around times of transition.

On-Ledger Decentralized Exchange

One of the biggest features that sets the XRP Ledger apart from other cryptocurrency networks is that it also contains a full currency exchange that runs on the XRP Ledger. Within this system, businesses (typically called “gateways”) can freely issue any currency they want to customers, and those customers can freely trade issued currencies for XRP or other issued currencies issued by any gateway. The XRP Ledger can execute atomic cross-currency transactions this way, using orders in the exchange to provide liquidity.

For more information on how the decentralized exchange works, see Decentralized Exchange. For more information on the gateway business model, see the Become an XRP Ledger Gateway.

Ubuntu16.04部署ethereum接口服务节点

更新仓库索引

root@localhost:~# apt update
Hit:1 http://mirrors.cloud.aliyuncs.com/ubuntu xenial InRelease
Hit:2 http://mirrors.cloud.aliyuncs.com/ubuntu xenial-updates InRelease
Hit:3 http://mirrors.cloud.aliyuncs.com/ubuntu xenial-security InRelease
Reading package lists... Done
Building dependency tree
Reading state information... Done
69 packages can be upgraded. Run 'apt list --upgradable' to see them.
root@localhost:~#

安装软件管理工具

root@localhost:~# apt-get install software-properties-common
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
linux-headers-4.4.0-87 linux-headers-4.4.0-87-generic
linux-image-4.4.0-87-generic linux-image-extra-4.4.0-87-generic
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
python3-pycurl python3-software-properties unattended-upgrades
Suggested packages:
libcurl4-gnutls-dev python-pycurl-doc python3-pycurl-dbg bsd-mailx
The following NEW packages will be installed:
python3-pycurl python3-software-properties software-properties-common
unattended-upgrades
0 upgraded, 4 newly installed, 0 to remove and 69 not upgraded.
Need to get 104 kB of archives.
After this operation, 799 kB of additional disk space will be used.
Do you want to continue? [Y/n]

添加软件源仓库

root@localhost:~# add-apt-repository ppa:ethereum/ethereum

More info: https://launchpad.net/~ethereum/+archive/ubuntu/ethereum
Press [ENTER] to continue or ctrl-c to cancel adding it

gpg: keyring `/tmp/tmpgbqt2ny9/secring.gpg' created
gpg: keyring `/tmp/tmpgbqt2ny9/pubring.gpg' created
gpg: requesting key 923F6CA9 from hkp server keyserver.ubuntu.com
gpg: /tmp/tmpgbqt2ny9/trustdb.gpg: trustdb created
gpg: key 923F6CA9: public key "Launchpad PPA for Ethereum" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
OK
root@localhost:~#

更新仓库索引

root@localhost:~# apt-get update
Hit:1 http://mirrors.cloud.aliyuncs.com/ubuntu xenial InRelease
Hit:2 http://mirrors.cloud.aliyuncs.com/ubuntu xenial-updates InRelease
Hit:3 http://mirrors.cloud.aliyuncs.com/ubuntu xenial-security InRelease
Get:4 http://ppa.launchpad.net/ethereum/ethereum/ubuntu xenial InRelease [17.5 kB]
Get:5 http://ppa.launchpad.net/ethereum/ethereum/ubuntu xenial/main amd64 Packages [5,944 B]
Get:6 http://ppa.launchpad.net/ethereum/ethereum/ubuntu xenial/main i386 Packages [5,956 B]
Get:7 http://ppa.launchpad.net/ethereum/ethereum/ubuntu xenial/main Translation-en [2,936 B]
Fetched 32.4 kB in 2s (12.3 kB/s)
Reading package lists... Done
root@localhost:~#

缺乏依赖 (跳过)

root@localhost:~# apt-get install cpp-ethereum
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
cpp-ethereum : Depends: alethzero but it is not going to be installed
Depends: mix-ide but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
root@localhost:~#

选用geth版本进行安装

root@localhost:~# apt-get install ethereum
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
linux-headers-4.4.0-87 linux-headers-4.4.0-87-generic
linux-image-4.4.0-87-generic linux-image-extra-4.4.0-87-generic
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
abigen bootnode evm geth puppeth rlpdump swarm wnode
The following NEW packages will be installed:
abigen bootnode ethereum evm geth puppeth rlpdump swarm wnode
0 upgraded, 9 newly installed, 0 to remove and 69 not upgraded.
Need to get 22.8 MB of archives.
After this operation, 86.1 MB of additional disk space will be used.
Do you want to continue? [Y/n]

查看安装路径

root@localhost:~# dpkg -L geth
/.
/usr
/usr/bin
/usr/bin/geth
/usr/share
/usr/share/doc
/usr/share/doc/geth
/usr/share/doc/geth/changelog.gz
/usr/share/doc/geth/AUTHORS.gz
/usr/share/doc/geth/copyright
root@localhost:~#

geth用法参数

root@localhost:~# geth --help
NAME:
geth - the go-ethereum command line interface

Copyright 2013-2018 The go-ethereum Authors

USAGE:
geth [options] command [command options] [arguments...]

VERSION:
1.8.12-stable-37685930

COMMANDS:
account Manage accounts
attach Start an interactive JavaScript environment (connect to node)
bug opens a window to report a bug on the geth repo
console Start an interactive JavaScript environment
copydb Create a local chain from a target chaindata folder
dump Dump a specific block from storage
dumpconfig Show configuration values
export Export blockchain into file
export-preimages Export the preimage database into an RLP stream
import Import a blockchain file
import-preimages Import the preimage database from an RLP stream
init Bootstrap and initialize a new genesis block
js Execute the specified JavaScript files
license Display license information
makecache Generate ethash verification cache (for testing)
makedag Generate ethash mining DAG (for testing)
monitor Monitor and visualize node metrics
removedb Remove blockchain and state databases
version Print version numbers
wallet Manage Ethereum presale wallets
help, h Shows a list of commands or help for one command

ETHEREUM OPTIONS:
--config value TOML configuration file
--datadir "/root/.ethereum" Data directory for the databases and keystore
--keystore Directory for the keystore (default = inside the datadir)
--nousb Disables monitoring for and managing USB hardware wallets
--networkid value Network identifier (integer, 1=Frontier, 2=Morden (disused), 3=Ropsten, 4=Rinkeby) (default: 1)
--testnet Ropsten network: pre-configured proof-of-work test network
--rinkeby Rinkeby network: pre-configured proof-of-authority test network
--syncmode "fast" Blockchain sync mode ("fast", "full", or "light")
--gcmode value Blockchain garbage collection mode ("full", "archive") (default: "full")
--ethstats value Reporting URL of a ethstats service (nodename:secret@host:port)
--identity value Custom node name
--lightserv value Maximum percentage of time allowed for serving LES requests (0-90) (default: 0)
--lightpeers value Maximum number of LES client peers (default: 100)
--lightkdf Reduce key-derivation RAM & CPU usage at some expense of KDF strength

DEVELOPER CHAIN OPTIONS:
--dev Ephemeral proof-of-authority network with a pre-funded developer account, mining enabled
--dev.period value Block period to use in developer mode (0 = mine only if transaction pending) (default: 0)

ETHASH OPTIONS:
--ethash.cachedir Directory to store the ethash verification caches (default = inside the datadir)
--ethash.cachesinmem value Number of recent ethash caches to keep in memory (16MB each) (default: 2)
--ethash.cachesondisk value Number of recent ethash caches to keep on disk (16MB each) (default: 3)
--ethash.dagdir "/root/.ethash" Directory to store the ethash mining DAGs (default = inside home folder)
--ethash.dagsinmem value Number of recent ethash mining DAGs to keep in memory (1+GB each) (default: 1)
--ethash.dagsondisk value Number of recent ethash mining DAGs to keep on disk (1+GB each) (default: 2)

TRANSACTION POOL OPTIONS:
--txpool.nolocals Disables price exemptions for locally submitted transactions
--txpool.journal value Disk journal for local transaction to survive node restarts (default: "transactions.rlp")
--txpool.rejournal value Time interval to regenerate the local transaction journal (default: 1h0m0s)
--txpool.pricelimit value Minimum gas price limit to enforce for acceptance into the pool (default: 1)
--txpool.pricebump value Price bump percentage to replace an already existing transaction (default: 10)
--txpool.accountslots value Minimum number of executable transaction slots guaranteed per account (default: 16)
--txpool.globalslots value Maximum number of executable transaction slots for all accounts (default: 4096)
--txpool.accountqueue value Maximum number of non-executable transaction slots permitted per account (default: 64)
--txpool.globalqueue value Maximum number of non-executable transaction slots for all accounts (default: 1024)
--txpool.lifetime value Maximum amount of time non-executable transaction are queued (default: 3h0m0s)

PERFORMANCE TUNING OPTIONS:
--cache value Megabytes of memory allocated to internal caching (default: 1024)
--cache.database value Percentage of cache memory allowance to use for database io (default: 75)
--cache.gc value Percentage of cache memory allowance to use for trie pruning (default: 25)
--trie-cache-gens value Number of trie node generations to keep in memory (default: 120)

ACCOUNT OPTIONS:
--unlock value Comma separated list of accounts to unlock
--password value Password file to use for non-interactive password input

API AND CONSOLE OPTIONS:
--rpc Enable the HTTP-RPC server
--rpcaddr value HTTP-RPC server listening interface (default: "localhost")
--rpcport value HTTP-RPC server listening port (default: 8545)
--rpcapi value API's offered over the HTTP-RPC interface
--ws Enable the WS-RPC server
--wsaddr value WS-RPC server listening interface (default: "localhost")
--wsport value WS-RPC server listening port (default: 8546)
--wsapi value API's offered over the WS-RPC interface
--wsorigins value Origins from which to accept websockets requests
--ipcdisable Disable the IPC-RPC server
--ipcpath Filename for IPC socket/pipe within the datadir (explicit paths escape it)
--rpccorsdomain value Comma separated list of domains from which to accept cross origin requests (browser enforced)
--rpcvhosts value Comma separated list of virtual hostnames from which to accept requests (server enforced). Accepts '*' wildcard. (default: "localhost")
--jspath loadScript JavaScript root path for loadScript (default: ".")
--exec value Execute JavaScript statement
--preload value Comma separated list of JavaScript files to preload into the console

NETWORKING OPTIONS:
--bootnodes value Comma separated enode URLs for P2P discovery bootstrap (set v4+v5 instead for light servers)
--bootnodesv4 value Comma separated enode URLs for P2P v4 discovery bootstrap (light server, full nodes)
--bootnodesv5 value Comma separated enode URLs for P2P v5 discovery bootstrap (light server, light nodes)
--port value Network listening port (default: 30303)
--maxpeers value Maximum number of network peers (network disabled if set to 0) (default: 25)
--maxpendpeers value Maximum number of pending connection attempts (defaults used if set to 0) (default: 0)
--nat value NAT port mapping mechanism (any|none|upnp|pmp|extip:<IP>) (default: "any")
--nodiscover Disables the peer discovery mechanism (manual peer addition)
--v5disc Enables the experimental RLPx V5 (Topic Discovery) mechanism
--netrestrict value Restricts network communication to the given IP networks (CIDR masks)
--nodekey value P2P node key file
--nodekeyhex value P2P node key as hex (for testing)

MINER OPTIONS:
--mine Enable mining
--minerthreads value Number of CPU threads to use for mining (default: 2)
--etherbase value Public address for block mining rewards (default = first account created) (default: "0")
--targetgaslimit value Target gas limit sets the artificial target gas floor for the blocks to mine (default: 4712388)
--gasprice "18000000000" Minimal gas price to accept for mining a transactions
--extradata value Block extra data set by the miner (default = client version)

GAS PRICE ORACLE OPTIONS:
--gpoblocks value Number of recent blocks to check for gas prices (default: 20)
--gpopercentile value Suggested gas price is the given percentile of a set of recent transaction gas prices (default: 60)

VIRTUAL MACHINE OPTIONS:
--vmdebug Record information useful for VM and contract debugging

LOGGING AND DEBUGGING OPTIONS:
--fakepow Disables proof-of-work verification
--nocompaction Disables db compaction after import
--verbosity value Logging verbosity: 0=silent, 1=error, 2=warn, 3=info, 4=debug, 5=detail (default: 3)
--vmodule value Per-module verbosity: comma-separated list of <pattern>=<level> (e.g. eth/*=5,p2p=4)
--backtrace value Request a stack trace at a specific logging statement (e.g. "block.go:271")
--debug Prepends log messages with call-site location (file and line number)
--pprof Enable the pprof HTTP server
--pprofaddr value pprof HTTP server listening interface (default: "127.0.0.1")
--pprofport value pprof HTTP server listening port (default: 6060)
--memprofilerate value Turn on memory profiling with the given rate (default: 524288)
--blockprofilerate value Turn on block profiling with the given rate (default: 0)
--cpuprofile value Write CPU profile to the given file
--trace value Write execution trace to the given file

METRICS AND STATS OPTIONS:
--metrics Enable metrics collection and reporting
--metrics.influxdb Enable metrics export/push to an external InfluxDB database
--metrics.influxdb.endpoint value InfluxDB API endpoint to report metrics to (default: "http://localhost:8086")
--metrics.influxdb.database value InfluxDB database name to push reported metrics to (default: "geth")
--metrics.influxdb.username value Username to authorize access to the database (default: "test")
--metrics.influxdb.password value Password to authorize access to the database (default: "test")
--metrics.influxdb.host.tag host InfluxDB host tag attached to all measurements (default: "localhost")

WHISPER (EXPERIMENTAL) OPTIONS:
--shh Enable Whisper
--shh.maxmessagesize value Max message size accepted (default: 1048576)
--shh.pow value Minimum POW accepted (default: 0.2)

DEPRECATED OPTIONS:
--fast Enable fast syncing through state downloads (replaced by --syncmode)
--light Enable light client mode (replaced by --syncmode)

MISC OPTIONS:
--help, -h show help


COPYRIGHT:
Copyright 2013-2018 The go-ethereum Authors

root@localhost:~#

启动服务

tom@localhost:~$ nohup geth --datadir "/data/ethereum" --cache 1024 \
--port 30303 --syncmode "fast" \
--rpc --rpcaddr 10.20.30.40 --rpcport 8545 \
--rpcapi "db,eth,net,web3,personal" &