observer

README

Observer - P2P network crawler

Observer crawls the Ethereum network and collects information about the nodes.

Build

make observer

Run

observer --datadir ... --nat extip:<IP> --port <PORT>

Where IP is your public IP, and PORT has to be open for incoming UDP traffic.

See observer --help for available options.

Report

To get the report about the currently known network state run:

observer report --datadir ...

Description

Observer uses discv4 protocol to discover new nodes. Starting from a list of preconfigured "bootnodes" it uses FindNode to obtain their "neighbor" nodes, and then recursively crawls neighbors of neighbors and so on. Each found node is re-crawled again a few times. If the node fails to be pinged after maximum attempts, it is considered "dead", but still re-crawled less often.

A separate "diplomacy" process is doing "handshakes" to obtain information about the discovered nodes. It tries to get RLPx Hello and Eth Status from each node. The handshake repeats a few times according to the configured delays.