Run a node

A Ferminux node downloads every block of chain 3961, re-executes it and checks the signature of the signer that confirmed it. Run one when you want to read the chain without trusting someone else's RPC, serve your own applications, or help the network relay blocks and transactions. The genesis and a bootnode are compiled into the binary, so an empty data directory joins the network with no configuration.

Signers and ordinary nodes

Every node runs the same binary. What differs is authorisation.

The signer set is recorded on the chain. Read it with clique_getSigners on any node, or in a console with clique.getSigners(). Signers are added or removed by a majority vote of the current signers, and every vote is visible in block headers. The foundation operates the signer set today. Blocks keep coming while more than half of the signers are online.

Running a node does not make it a signer and earns nothing on its own. An open validator programme is being built: validator nodes will check every block and sign checkpoints against a 2,000 FMX deposit per seat. They will not produce blocks. The programme is not live yet; the page has a waitlist.

The current release: A (v1.1.0-posa)

Release A is the binary that carries the authority fork at block 160,000. The network's own nodes run it, and it is what the installer fetches.

The archives are at https://ferminux.net/downloads/, listed in SHA256SUMS.txt. That list is not signed yet, so it proves a download is complete, not that the server is honest. The table above is a cross-check from the same operator, not a signature.

Windows: no current build is published. The ferminux-geth-windows-amd64.zip still on the download server is the pre-fork package: it stops following the chain at block 159,999. Do not use it. Run the Linux build under WSL2, or use Docker (below).

Intel Macs: no build is published. Build from source or use Docker.

Install (Linux and Apple Silicon Macs)

curl -fsSL https://ferminux.net/install.sh | bash

The script picks the archive for your platform, checks its SHA-256 against the list, installs the binary as ferminux in /usr/local/bin (or ~/.local/bin without sudo), and adds ferminux-geth as a second name for the same binary.

Start it:

ferminux --cache 512

That is a complete node. --cache sets the database cache in MB. Without it the client assumes a large machine and reserves 4 GB, which gets small servers killed for running out of memory; 256 to 1,024 is plenty for this chain.

The chain is small (a synced data directory is a few hundred MB), so a fresh node catches up in minutes. Check progress against the explorer:

ferminux attach --exec 'eth.blockNumber'
ferminux attach --exec 'eth.syncing'          # false once it has caught up

What a healthy start looks like

Release A prints a banner that includes these lines:

INFO Writing default Ferminux genesis block
INFO Chain ID:  3961 (ferminux)
INFO  - Ferminux PoSA (Clique authority from this block): 160000
INFO Ferminux proof-of-authority engine armed  posaBlock=160,000 period=7 epoch=30000 signers=5 ...
WARN Ferminux PoSA checkpoint hash is unset: block PosaBlock-1 is not pinned

• The WARN line is expected on release A. The next release pins that block's hash.
• signers=5 is the set compiled in for the fork block. The set has changed by vote since then; the live list is clique.getSigners().
• Some banner lines are inherited from the upstream client and name another network or the pre-fork engine. Troubleshooting explains them.

Where your data lives

Inside it:

Pass --datadir /path to put everything somewhere else. Flags always go before positional arguments: ferminux attach --exec 'eth.blockNumber' /path/geth.ipc.

Run it as a service (systemd)

sudo useradd --system --home /var/lib/ferminux --shell /usr/sbin/nologin ferminux
sudo mkdir -p /var/lib/ferminux && sudo chown ferminux:ferminux /var/lib/ferminux

sudo tee /etc/systemd/system/ferminux.service >/dev/null <<'UNIT'
[Unit]
Description=Ferminux node (chain 3961)
After=network-online.target
Wants=network-online.target

[Service]
User=ferminux
ExecStart=/usr/local/bin/ferminux --datadir /var/lib/ferminux --cache 512 \
  --http --http.addr 127.0.0.1 --http.port 8545 --http.api eth,net,web3,txpool
Restart=always
RestartSec=5
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
UNIT

sudo systemctl daemon-reload
sudo systemctl enable --now ferminux
journalctl -fu ferminux

Open 30303/tcp and 30303/udp in your firewall if you want other nodes to reach yours. A node with only outbound connections still syncs.

Docker

The source tree's chain/ directory builds an image whose entry point is ferminux:

cd chain
docker build -t ferminux:local .

docker run -d --name ferminux --restart unless-stopped \
  -v ferminux-data:/root/.ferminux \
  -p 30303:30303 -p 30303:30303/udp \
  -p 127.0.0.1:8545:8545 \
  ferminux:local --cache 512 --http --http.addr 0.0.0.0 --http.api eth,net,web3

Inside the container --http.addr 0.0.0.0 is needed for the port mapping to work; the 127.0.0.1:8545 mapping keeps it reachable from this machine only.

Build from source

cd chain
GOTOOLCHAIN=go1.20.14 make ferminux     # -> build/bin/ferminux (+ ferminux-geth, geth)

The client is on the go-ethereum v1.10.26 line and needs Go 1.18 to 1.20; the GOTOOLCHAIN setting fetches Go 1.20.14 when your installed Go is newer. The source builds the same consensus rules as release A.

JSON-RPC, and how not to get drained

Local HTTP and WebSocket endpoints:

ferminux --http --http.addr 127.0.0.1 --http.port 8545 --http.api eth,net,web3,txpool
ferminux --ws   --ws.addr 127.0.0.1   --ws.port 8546   --ws.api eth,net,web3

Check it answers (expect "result":"0xf79"):

curl -s -X POST -H 'Content-Type: application/json' \
  --data '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}' \
  http://127.0.0.1:8545

Rules worth keeping:

• Keep --http.addr 127.0.0.1. To serve other machines, put a reverse proxy with TLS and rate limits in front, as the public endpoint does.
• Only eth, net, web3 and txpool belong on an HTTP or WebSocket endpoint. Never add personal, admin, debug or any other namespace. Sign transactions in a wallet or library, not on the node.
• --http.corsdomain '*' and --http.vhosts '*' are for local development only.
• Do not pass network presets such as --mainnet or --sepolia, or any --override.* flag. They still parse, and they do not do anything useful on this client.

Confirm you are on the right chain

ferminux attach --exec 'eth.chainId()'          # 3961
ferminux attach --exec 'eth.getBlock(0).hash'   # 0x1b62e052…92fadf
ferminux attach --exec 'clique.getSigners()'    # today's authorised set

Then compare eth.blockNumber with the explorer. If your node sits at 159,999, read this.