OpenSSH is a suite of secure networking tools based on the SSH protocol. Developed as part of OpenBSD, it became the standard implementation for secure remote access and is installed on virtually every Unix-like system.
Origins
After SSH Communications Security made SSH non-free for commercial use, the OpenBSD project developed OpenSSH from the last free version. Theo de Raadt and team built it into the standard SSH implementation.
Key Components
OpenSSH provides:
- ssh: Secure shell client
- sshd: SSH server daemon
- scp: Secure copy
- sftp: Secure file transfer
- ssh-keygen: Key generation
- ssh-agent: Authentication agent
Security Features
OpenSSH pioneered security practices:
- Privilege separation
- Strong cryptography
- Key-based authentication
- Frequent security audits
Ubiquity
OpenSSH is effectively universal:
- Default on all Linux distributions
- Standard on macOS and BSDs
- Available on Windows
- Foundation for secure infrastructure management
Impact
OpenSSH made secure remote access standard. Before SSH, telnet transmitted passwords in plaintext. OpenSSH’s availability as free software ensured encrypted connections became the default everywhere.