op-challenger

Package Name: optimism-op-challenger

The Fault Proof Challenger for the Optimism Stack. It monitors the Layer 1 and Layer 2 chains to detect and challenge invalid state transitions.

Configuration

The configuration file is located at /etc/ethereum/op-challenger.conf.

You can edit this file to change the command line arguments passed to the client. After modifying the file, restart the service:

sudo systemctl restart op-challenger

Trace Types

The --trace-type flag determines which fault proof VMs are used:

  • cannon - MIPS-based VM (default, recommended)

  • cannon-kona - Cannon with Kona host

  • permissioned - Permissioned games (uses Cannon)

  • asterisc - RISC-V based VM (requires asterisc binary)

  • asterisc-kona - Asterisc with Kona host

Important

Recent versions of op-challenger default to cannon,asterisc-kona,cannon-kona, which requires the Asterisc binary. To use only Cannon, explicitly set:

TRACE_TYPE="cannon"

To use Kona (cannon-kona), ensure the kona package is installed:

sudo apt install kona
# In /etc/ethereum/op-challenger.conf:
TRACE_TYPE="cannon-kona"
CANNON_KONA_SERVER="/usr/bin/kona-host"

Service Management

The systemd service name is op-challenger.

sudo systemctl start op-challenger
sudo systemctl stop op-challenger
sudo systemctl status op-challenger
sudo systemctl enable op-challenger

Data Directory

The default configuration suggests using:

  • /home/ethereum/.op-challenger

Maintainer

Upstream Project

See Running a Guardian Node (Optimism Challenger) for a detailed operational guide.