Alternatives to OpenBSD

A free, security-focused BSD Unix operating system that runs on many hardware platforms. The listings below can replace it for an important use case. Each note says what changes if you switch.

Replacements

Listings that take over the same core job as OpenBSD.

  • HardenedBSD

    A security-hardened fork of FreeBSD that adds exploit mitigations such as ASLR.

    FreeOpen sourceCommand line

    HardenedBSD is a hardened FreeBSD fork adding mitigations like ASLR, so moving means FreeBSD's base system and sparser documentation on its homepage.

  • Kicksecure

    Hardened Debian derivative with kernel hardening and exploit mitigations.

    FreeOpen sourceLinux

    Kicksecure is a hardened Debian derivative that can convert an existing Debian install, bringing Linux hardware support but hardening that breaks some software.

  • OPNsense

    An open-source firewall and routing platform based on FreeBSD that you install on your own hardware.

    FreeOpen sourceSelf-hosted

    OPNsense covers OpenBSD's firewall and router role as a FreeBSD-based appliance with a web interface, rather than a general-purpose operating system.

  • IPFire

    A hardened Linux-based firewall distribution with VPN support, network segmentation and a web management console.

    FreeOpen sourceSelf-hosted

    IPFire is a Linux firewall distribution with a web console and built-in WireGuard, OpenVPN and IPsec, suited to firewall use rather than general servers.

Also worth comparing

These listings name OpenBSD as their own alternative, so the relationship runs both ways.

  • DragonFly BSD

    A free BSD operating system with the HAMMER2 filesystem, derived from FreeBSD.

    FreeOpen sourceCommand line

    OpenBSD focuses on security and correctness in the default install, with integrated cryptography and OpenSSH, and runs on many hardware platforms.

  • FreeBSD

    An open source Unix-like operating system with native ZFS, jails and the bhyve hypervisor.

    FreeOpen sourceSelf-hostedCommand line

    OpenBSD puts security first with integrated cryptography and OpenSSH, suiting firewalls and routers, but lacks FreeBSD's integrated ZFS, jails and bhyve.

  • NetBSD

    A free, highly portable Unix-like operating system that runs on dozens of hardware platforms.

    FreeOpen sourceCommand line

    OpenBSD focuses on security in the default install and integrated cryptography, runs on many platforms, but supports fewer architectures than NetBSD's wide hardware range.

  • Qubes OS

    Operating system that compartmentalises work into isolated virtual machines.

    FreeOpen sourceLinux

    OpenBSD is a security-focused BSD Unix with a strong default install record, but it offers no virtual machine compartmentalisation and puts less focus on desktop convenience.

Similar software

Related functionality, not a direct replacement.