Requirements

Operating System#

JustC2 is developed and tested on Linux. The server and extenders can be built on any Linux distribution. The client requires a desktop environment with Qt6 support.

Recommended distributions:

• Kali Linux (recommended for red team operations)
• Ubuntu 22.04+ / Debian 12+
• Fedora 38+

Server Requirements#

Go#

The teamserver and extenders require Go 1.26.5 or later.

# Check your Go version
go version

# If you need to install or upgrade Go
wget https://go.dev/dl/go1.26.5.linux-amd64.tar.gz
sudo rm -rf /usr/local/go
sudo tar -C /usr/local -xzf go1.26.5.linux-amd64.tar.gz

# Add to your shell profile
export PATH=$PATH:/usr/local/go/bin

Build Tools#

# Debian/Ubuntu/Kali
sudo apt-get install build-essential git

# Fedora
sudo dnf install gcc gcc-c++ make git

Client Requirements#

The JustClient is a C++ Qt6 application and requires:

Qt6#

# Debian/Ubuntu/Kali
sudo apt-get install qt6-base-dev qt6-websockets-dev qt6-5compat-dev \
    qt6-base-private-dev libgl1-mesa-dev

# Fedora
sudo dnf install qt6-qtbase-devel qt6-qtwebsockets-devel qt6-qt5compat-devel

CMake#

# Debian/Ubuntu/Kali
sudo apt-get install cmake

# Fedora
sudo dnf install cmake

Additional Libraries#

The client depends on several libraries that are included in the source tree:

• Qlementine — Theme engine (built automatically)
• KDDockWidgets — Docking framework (built automatically)
• Konsole — Terminal emulator widget (built automatically)

Docker Requirements#

If you prefer to build with Docker, you only need:

• Docker 20.10+
• Docker Compose v2+

# Install Docker (Debian/Ubuntu/Kali)
sudo apt-get install docker.io docker-compose-v2

# Add your user to the docker group
sudo usermod -aG docker $USER

Runtime Requirements#

Server Runtime#

• Linux x86_64
• OpenSSL (for TLS certificate generation)
• Network access on the configured port (default: 4321)
• Sufficient disk space for the SQLite database and downloaded files

Agent Build Runtime#

The server compiles agent payloads at runtime. This requires:

• Go 1.26.5+ installed on the server machine and available in $PATH
• The agent source code present in the extender directories (e.g., extenders/gopher_agent/src_gopher/)

Client Runtime#

• Linux x86_64 with a desktop environment
• Qt6 runtime libraries
• Network connectivity to the teamserver

Hardware Recommendations#

The server is lightweight, but agent payload compilation and concurrent tunnel operations can increase resource usage.