Geth

Installing and configuring Go-Ethereum as a systemd service.

Geth (Go-Ethereum)

Geth is the official Golang implementation of the Ethereum protocol. It is the most widely used client due to its stability, extensive documentation, and tooling support.

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🛡️ Role: Geth will connect to the peer-to-peer network to download block data and execute transactions. It will expose an Engine API that allows the Consensus Client (Step 4) to control it.

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1. Install Geth

We recommended installing Geth via the official Personal Package Archive (PPA). This ensures you can easily update the node with a simple apt update in the future.

# 1. Enable the PPA
sudo add-apt-repository -y ppa:ethereum/ethereum

# 2. Update package lists
sudo apt update

# 3. Install Geth
sudo apt install -y geth

# 4. Verify installation
geth version

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2. Configure Systemd Service

We will run Geth as a background service using systemd. This ensures the node starts automatically on reboot and runs as the dedicated ethereum user we created in Step 2.

Create the service file:

sudo nano /etc/systemd/system/geth.service

Paste the following configuration:

[Unit]
Description=Geth Execution Client
After=network.target

[Service]
User=ethereum
Group=ethereum
Type=simple
Restart=always
RestartSec=5

# Execution Command
ExecStart=/usr/bin/geth \
  --networkid 1 \
  --datadir /home/ethereum/execution \
  --authrpc.jwtsecret /home/ethereum/jwt/jwt.hex \
  --authrpc.addr 127.0.0.1 \
  --authrpc.port 8551 \
  --authrpc.vhosts localhost \
  --http \
  --http.addr 0.0.0.0 \
  --http.port 8545 \
  --http.api eth,net,admin \
  --state.scheme path

# Resource Limits
LimitNOFILE=65535

[Install]
WantedBy=multi-user.target

🔍 Flag Explanation:

• --datadir: Points to the folder we created in Step 2.

• --authrpc.jwtsecret: The critical token allowing the Consensus Client to talk to Geth.

• --http: Enables the JSON-RPC API (for your dApps or wallets).

• --http.addr 0.0.0.0: Listens on all interfaces (Safe because we configured UFW Firewall in Step 2).

• --http.api eth,net,admin: The Engine API is not included here — it runs automatically over the authenticated RPC port (--authrpc.*) and should not be exposed on the public HTTP interface.

• --state.scheme path: Uses path-based storage, which is the recommended scheme for better performance and proper pruning support.

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3. Start the Service

Reload the systemd daemon to read the new file, then enable and start Geth.

# Reload systemd
sudo systemctl daemon-reload

# Enable Geth to start on boot
sudo systemctl enable geth

# Start Geth immediately
sudo systemctl start geth

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4. Verify Status

Geth should now be running. However, it will not start syncing properly yet because it is waiting for a Consensus Client (Step 4) to tell it what the "head" of the chain is.

Check the logs to ensure it started correctly:

sudo journalctl -fu geth

Expected Output: You should see logs indicating:

• Starting Geth on Ethereum mainnet...

• UDP listener up (P2P Networking active)

⚠️ Warning: You might see Post-merge network, but no beacon client seen. This is normal until we complete Step 4.