cryptcat

Cryptcat is a simple Unix utility that reads and writes data across network connections using TCP or UDP protocols while encrypting the transmitted data with Twofish encryption. It is designed to be a reliable back-end tool that can be used directly or driven by other programs and scripts, making it feature-rich for network debugging and exploration. The tool can create various types of connections and includes built-in capabilities for tasks like data transfer between systems.

Common use cases include secure file transfers, remote data piping, and establishing encrypted network tunnels. For example, it can listen for inbound connections on a specified port and redirect received data to a file, or connect to a remote host to send local data securely. This makes it valuable in penetration testing and cybersecurity scenarios requiring encrypted communication over untrusted networks.

As a Twofish-enabled version of nc(1), cryptcat maintains compatibility with netcat workflows while adding encryption, ensuring data confidentiality during transmission.

Cryptcat operates by establishing TCP or UDP connections, encrypting all data transmitted using Twofish encryption. In listen mode (-l -p port), it waits for inbound connections and can redirect traffic (e.g., to files). In connect mode, it links to a remote hostname and port, piping local data securely. Options like -n disable DNS resolution for numeric IP use, and it supports source-routing, delays, and hex dumping for advanced network operations.