Sentry
P2P network management
Sentry connects Erigon to the Ethereum P2P network, enabling the discovery of other participants across the Internet and secure communication with them. It performs these main functions:
-
Peer discovery via the following:
- Kademlia DHT
- DNS lookup
- Configured static peers
- Node info saved in the database
- Boot nodes pre-configured in the source code
-
Peer management:
- handshakes
- holding p2p connection even if Erigon is restarted
The ETH core interacts with the Ethereum p2p network through the Sentry component. Sentry provides a simple interface to the core, with functions to download data, receive notifications about gossip messages, upload data on request from peers, and broadcast gossip messages either to a selected set of peers or to all peers.
Running with an external Sentry or multiple Sentries
It is possible to have multiple Sentry to increase connectivity to the network or to obscure the location of the core computer. In this case it is necessary to define address and port of each Sentry that should be connected to the Core.
Before using the Sentry component the executable must be built. Head over to /erigon directory and type:
make sentry
Then it can be launched as an independent component with the command:
./build/bin/sentry
Example
In this example we will run an instance of Erigon and Sentry on the same machine.
Following is the Sentry client running separately:
screen ./build/bin/sentry --datadir=~/.local/share/erigon
And here is Erigon attaching to it
./build/bin/erigon --internalcl --snapshots=true --sentry.api.addr=127.0.0.1:9091
Erigon might be attached to several Sentry instances running across different machines. As per Erigon help:
--sentry.api.addr value
Where value is comma separated sentry addresses '
More info
For other information regarding Sentry functionality, configuration, and usage, please refer to the embedded file you can find in your compiled Erigon folder at ./cmd/sentry/README.md.
Command Line Options
To display available options for Sentry digit:
./build/bin/sentry --help
The --help flag listing is reproduced below for your convenience.
Run p2p sentry
Usage:
sentry [flags]
Flags:
--datadir string Data directory for the databases (default "/home/bloxster/.local/share/erigon")
--diagnostics.disabled Disable diagnostics
--diagnostics.endpoint.addr string Diagnostics HTTP server listening interface (default "127.0.0.1")
--diagnostics.endpoint.port uint Diagnostics HTTP server listening port (default 6062)
--diagnostics.speedtest Enable speed test
--discovery.dns strings Sets DNS discovery entry points (use "" to disable DNS)
--healthcheck Enabling grpc health check
-h, --help help for sentry
--log.console.json Format console logs with JSON
--log.console.verbosity string Set the log level for console logs (default "info")
--log.delays Enable block delay logging
--log.dir.disable disable disk logging
--log.dir.json Format file logs with JSON
--log.dir.path string Path to store user and error logs to disk
--log.dir.prefix string The file name prefix for logs stored to disk
--log.dir.verbosity string Set the log verbosity for logs stored to disk (default "info")
--log.json Format console logs with JSON
--maxpeers int Maximum number of network peers (network disabled if set to 0) (default 32)
--maxpendpeers int Maximum number of TCP connections pending to become connected peers (default 1000)
--metrics Enable metrics collection and reporting
--metrics.addr string Enable stand-alone metrics HTTP server listening interface (default "127.0.0.1")
--metrics.port int Metrics HTTP server listening port (default 6061)
--nat string NAT port mapping mechanism (any|none|upnp|pmp|stun|extip:<IP>)
"" or "none" Default - do not nat
"extip:77.12.33.4" Will assume the local machine is reachable on the given IP
"any" Uses the first auto-detected mechanism
"upnp" Uses the Universal Plug and Play protocol
"pmp" Uses NAT-PMP with an auto-detected gateway address
"pmp:192.168.0.1" Uses NAT-PMP with the given gateway address
"stun" Uses STUN to detect an external IP using a default server
"stun:<server>" Uses STUN to detect an external IP using the given server (host:port)
--netrestrict string Restricts network communication to the given IP networks (CIDR masks)
--nodiscover Disables the peer discovery mechanism (manual peer addition)
--p2p.allowed-ports uints Allowed ports to pick for different eth p2p protocol versions as follows <porta>,<portb>,..,<porti> (default [30303,30304,30305,30306,30307])
--p2p.protocol uint Version of eth p2p protocol (default 68)
--port int Network listening port (default 30303)
--pprof Enable the pprof HTTP server
--pprof.addr string pprof HTTP server listening interface (default "127.0.0.1")
--pprof.cpuprofile string Write CPU profile to the given file
--pprof.port int pprof HTTP server listening port (default 6060)
--sentry.api.addr string grpc addresses (default "localhost:9091")
--staticpeers strings Comma separated enode URLs to connect to
--trace string Write execution trace to the given file
--trustedpeers strings Comma separated enode URLs which are always allowed to connect, even above the peer limit
--verbosity string Set the log level for console logs (default "info")