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docs: add page on devp2p (#26076)
* add page on devp2p * Update docs/_interface/devp2p.md Co-authored-by: Martin Holst Swende <martin@swende.se> * add example enrdump Co-authored-by: Martin Holst Swende <martin@swende.se>pull/26204/head
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title: devp2p |
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sort-key: Q |
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--- |
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[DevP2P](https://github.com/ethereum/devp2p) is a set of network protocols |
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that form the Ethereum peer-to-peer network. The DevP2P specifications |
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define precisely how nodes should find each other and communicate. |
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Geth implements the DevP2P specifications in Go. |
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The DevP2P stack includes the low-level peer-to-peer protocols that |
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define discovery and secure sessions between nodes such as: |
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- [Ethereum Node Records](https://github.com/ethereum/devp2p/blob/master/enr.md): A standard format for connectivity information for a node |
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- [Discovery protocol](https://github.com/ethereum/devp2p/blob/master/discv4.md): Defines how nodes find each other. |
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- [RLPx protocol](https://github.com/ethereum/devp2p/blob/master/rlpx.md): Defines a TCP based transport system for communication between nodes. |
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DevP2P also includes the RLPx-based application level protocols including: |
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- [Ethereum Wire Protocol](https://github.com/ethereum/devp2p/blob/master/caps/eth.md): facilitates exchange of blockchain data between peers |
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- [Ethereum Snapshot Protocol](https://github.com/ethereum/devp2p/blob/master/caps/snap.md): enables exchange of snapshots between peers |
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- [Light Ethereum Subprotocol](https://github.com/ethereum/devp2p/blob/master/caps/les.md): protocol used by light clients |
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To debug and develop these networking components, Geth includes a command |
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line tool called `devp2p`. |
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This page will outline some of `devp2p`s built-in tools. |
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## ENR Decoding |
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Ethereum Node Records can be decoded, verified and displayed to the terminal |
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using `enrdump`. It takes the ENR in its encoded form, which is the base64 |
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encoding of its RLP representation. A decoded human-readable text representation |
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is displayed. |
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Use `devp2p enrdump <base64>` to verify and display an Ethereum Node Record. |
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The following is an example of the data returned by `enrdump`: |
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```terminal |
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./devp2p enrdump "enr:-J24QG3pjTFObcDvTOTJr2qPOTDH3-YxDqS47Ylm-kgM5BUwb1oD5Id6fSRTfUzTahTa7y4TWx_HSV7wri7T6iYtyAQHg2V0aMfGhLjGKZ2AgmlkgnY0gmlwhJ1a19CJc2VjcDI1NmsxoQPlCNb7N__vcnsNC8YYkFkmNj8mibnR5NuvSowcRZsLU4RzbmFwwIN0Y3CCdl-DdWRwgnZf" Node ID: 001816492db22f7572e9eea1c871a2ffe75c28162a9fbc5a9d240e480a7c176f URLv4: ./devp2p enrdump "enr:-J24QG3pjTFObcDvTOTJr2qPOTDH3-YxDqS47Ylm-kgM5BUwb1oD5Id6fSRTfUzTahTa7y4TWx_HSV7wri7T6iYtyAQHg2V0aMfGhLjGKZ2AgmlkgnY0gmlwhJ1a19CJc2VjcDI1NmsxoQPlCNb7N__vcnsNC8YYkFkmNj8mibnR5NuvSowcRZsLU4RzbmFwwIN0Y3CCdl-DdWRwgnZf" |
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Node ID: 001816492db22f7572e9eea1c871a2ffe75c28162a9fbc5a9d240e480a7c176f |
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URLv4: enode://e508d6fb37ffef727b0d0bc618905926363f2689b9d1e4dbaf4a8c1c459b0b534dcdf84342b78250a6dc013c9ee9f89d095d7a6d1ef0c5f4c57a083b22c557ef@157.90.215.208:30303 |
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Record has sequence number 7 and 7 key/value pairs. |
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"eth" c7c684b8c6299d80 |
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"id" "v4" |
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"ip" 157.90.215.208 |
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"secp256k1" a103e508d6fb37ffef727b0d0bc618905926363f2689b9d1e4dbaf4a8c1c459b0b53 |
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"snap" c0 |
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"tcp" 30303 |
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"udp" 30303 |
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``` |
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Read more on [Ethereum Node Records](https://ethereum.org/en/developers/docs/networking-layer/network-addresses/#enr) |
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or browse the [specs](https://github.com/ethereum/devp2p/blob/591edbd36eb57280384d07373a818c00bddf3b31/enr.md). |
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## Node Key Management |
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The `devp2p key ...` command family deals with node key files. |
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Run `devp2p key generate mynode.key` to create a new node key in the `mynode.key` file. |
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Run `devp2p key to-enode mynode.key -ip 127.0.0.1 -tcp 30303` to create an |
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enode:// URL corresponding to the given node key and address information. |
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## Maintaining DNS Discovery Node Lists |
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The devp2p command can create and publish DNS discovery node lists. Examples of such lists are the [discv4-dns-lists](https://github.com/ethereum/discv4-dns-lists). These lists are generated by using the `devp2p` crawler and dns tools. The lists are published both to github and to DNS, on the `ethdisco.net` domain. |
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Run `devp2p dns sign <directory>` to update the signature of a DNS discovery tree. |
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Run `devp2p dns sync <enrtree-URL>` to download a complete DNS discovery tree. |
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Run `devp2p dns to-cloudflare <directory>` to publish a tree to CloudFlare DNS. |
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Run `devp2p dns to-route53 <directory>` to publish a tree to Amazon Route53. |
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More information about these commands can be found in the |
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[DNS Discovery Setup Guide](https://geth.ethereum.org/docs/developers/dns-discovery-setup). |
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## Node Set Utilities |
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There are several commands for working with JSON node set files. These files are generated |
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by the discovery crawlers and DNS client commands. Node sets also used as the input of |
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the DNS deployer commands. |
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Run `devp2p nodeset info <nodes.json>` to display statistics of a node set. |
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Run `devp2p nodeset filter <nodes.json> <filter flags...>` to write a new, filtered |
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node set to standard output. The following filters are supported: |
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- `-limit <N>` limits the output set to N entries, taking the top N nodes by score |
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- `-ip <CIDR>` filters nodes by IP subnet |
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- `-min-age <duration>` filters nodes by 'first seen' time |
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- `-eth-network <mainnet/goerli/sepolia>` filters nodes by "eth" ENR entry |
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- `-les-server` filters nodes by LES server support |
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- `-snap` filters nodes by snap protocol support |
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For example, given a node set in `nodes.json`, you could create a filtered set containing |
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up to 20 eth mainnet nodes which also support snap sync using this command: |
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```sh |
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devp2p nodeset filter nodes.json -eth-network mainnet -snap -limit 20 |
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``` |
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## Discovery v4 Utilities |
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The `devp2p discv4 ...` command family deals with the |
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[Node Discovery v4](https://github.com/ethereum/devp2p/tree/master/discv4.md) protocol. |
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Run `devp2p discv4 ping <enode/ENR>` to ping a node. |
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Run `devp2p discv4 resolve <enode/ENR>` to find the most recent node record of a node in the DHT. |
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Run `devp2p discv4 crawl <nodes.json path>` to create or update a JSON node set. |
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## Discovery v5 Utilities |
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The `devp2p discv5 ...` command family deals with the |
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[Node Discovery v5](https://github.com/ethereum/devp2p/tree/master/discv5/discv5.md) |
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protocol. This protocol is currently under active development. |
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Run `devp2p discv5 ping <ENR>` to ping a node. |
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Run `devp2p discv5 resolve <ENR>` to find the most recent node record of a node |
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in the discv5 DHT. |
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Run `devp2p discv5 listen` to run a Discovery v5 node. |
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Run `devp2p discv5 crawl <nodes.json path>` to create or update a JSON node set containing discv5 nodes. |
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## Discovery Test Suites |
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The devp2p command also contains interactive test suites for Discovery v4 |
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and Discovery v5. To run these tests a networking environment must be set up |
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with two separate UDP listening addresses are available on the same machine. |
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The two listening addresses must also be routed such that they are able to reach |
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the node you want to test. |
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For example, to run the test on the local host when the node under test is also on |
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the local host, assign two IP addresses (or a larger range) to the loopback interface. |
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On macOS, this can be done by executing the following command: |
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```sh |
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sudo ifconfig lo0 add 127.0.0.2 |
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``` |
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Either test suite can then be run as follows: |
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1. Start the node under test first, ensuring that it won't talk to the Internet |
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(i.e. disable bootstrapping). An easy way to prevent unintended connections |
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to the global DHT is listening on `127.0.0.1`. |
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2. Get the ENR of the node and store it in the `NODE` environment variable. |
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3. Start the test by running `devp2p discv5 test -listen1 127.0.0.1 -listen2 127.0.0.2 $NODE`. |
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## Eth Protocol Test Suite |
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The Eth Protocol test suite is a conformance test suite for the |
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[eth protocol](https://github.com/ethereum/devp2p/blob/master/caps/eth.md). |
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To run the eth protocol test suite, the node needs to be initialized as follows: |
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1. initialize the Geth node with the `genesis.json` file contained in the `testdata` directory |
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2. import the `halfchain.rlp` file in the `testdata` directory |
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3. run Geth with the following flags: |
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```sh |
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geth --datadir <datadir> --nodiscover --nat=none --networkid 19763 --verbosity 5 |
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``` |
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Then, run the following command, replacing `<enode>` with the enode of |
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the Geth node: |
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```sh |
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devp2p rlpx eth-test <enode> cmd/devp2p/internal/ethtest/testdata/chain.rlp cmd/devp2p/internal/ethtest/testdata/genesis.json |
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``` |
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Repeat the above process (re-initialising the node) in order to run the Eth |
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Protocol test suite again. |
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### Eth66 Test Suite |
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The Eth66 test suite is also a conformance test suite for the eth 66 protocol |
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version specifically. To run the eth66 protocol test suite, initialize a Geth |
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node as described above and run the following command, replacing `<enode>` with |
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the enode of the Geth node: |
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```sh |
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devp2p rlpx eth66-test <enode> cmd/devp2p/internal/ethtest/testdata/chain.rlp cmd/devp2p/internal/ethtest/testdata/genesis.json |
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``` |
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## Summary |
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This page introduced the DevP2P stack that defines Ethereum's peer-to-peer network |
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and the `devp2p` command line tool that comes bundled with Geth. The `devp2p` |
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tools enables Geth developers to work on the peer-to-peer network. |
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