OpenBSD for macOS Users

This quickstart introduces macOS administrators to OpenBSD 7.8 by mapping familiar concepts to OpenBSD tooling and conventions. It highlights practical differences; it is not an exhaustive comparison nor a discussion of philosophy. The guide assumes OpenBSD is already installed and you have command-line access.

Shells #

On OpenBSD, the default shell for both root and regular users is the Korn shell, ksh(1) . On modern macOS systems, new user accounts default to zsh. OpenBSD’s ksh(1) implements a superset of the traditional Bourne shell language.

Alternative shells (e.g., Bash, Zsh) are available as packages; see pkg_add(1) and chsh(1) .

Recommendation: Do not change root’s shell to a package-provided shell. Non-base shells live under /usr/local/bin, which may be unavailable in a limited-recovery scenario. The base ksh(1) resides in /bin.

# Install common alternative shells (from a regular account via doas(1))
$ doas pkg_add bash zsh  # Install Bash and Zsh
$ chsh -s /usr/local/bin/zsh  # Change your login shell to Zsh

Privilege escalation: doas (instead of macOS sudo) #

OpenBSD provides doas(1) in the base system for privilege escalation (macOS ships sudo). Configure OpenBSD’s tool via doas.conf(5) . A documented example exists in /etc/examples/.

$ doas cp /etc/examples/doas.conf /etc/doas.conf  # Start from the example configuration

By default, each invocation prompts for a password. To cache authentication similarly to many sudo configurations, add persist:

permit persist keepenv :wheel

A sudo package is available if required; see sudo(8) .

Software management #

Unlike macOS, where third-party package managers such as Homebrew or MacPorts are common, OpenBSD provides an official, integrated binary package system. Prefer prebuilt packages; see packages(7) . Building from ports is documented in ports(7) .

Installing and removing packages #

Install prebuilt packages with pkg_add(1) :

$ doas pkg_add nginx  # Install Nginx

Remove packages with pkg_delete(1) :

$ doas pkg_delete nginx  # Remove Nginx

List installed packages with pkg_info(1) :

$ pkg_info  # List installed packages

Updating (same release) #

OpenBSD ships binary patches for the base system via syspatch(8) . This is broadly analogous to macOS Software Update for the operating system, not third-party software.

$ doas syspatch -c  # Show available base patches
$ doas syspatch     # Apply base patches (reboot if required)

Update installed packages to the latest for your release:

$ doas pkg_add -Uu  # Upgrade all packages within the current release

Upgrading (to a new release) #

Use sysupgrade(8) to fetch and perform a release upgrade. After the reboot, complete any configuration merges with sysmerge(8) if prompted, then update packages.

$ doas sysupgrade  # Upgrade base to the next OpenBSD release
$ doas pkg_add -Uu # Update packages after the base upgrade

Networking #

On macOS, interfaces often appear as en0, en1, and so on. OpenBSD names interfaces by driver, for example em0 (Intel), re0 (Realtek), and bge0 (Broadcom). See ifconfig(8) for details.

Interface configuration with hostname.if #

Per-interface configuration lives in hostname.if(5) , where if is the interface name (e.g., /etc/hostname.em0). This replaces macOS command-line tools such as networksetup and scutil for persistent settings.

Static IPv4:

inet 10.0.0.100 255.255.255.0

Static IPv6:

inet6 2001:db8:6000:9344::154 64

DHCP:

dhcp

Apply configuration from files using netstart(8) :

$ doas sh /etc/netstart      # Reload all interfaces
$ doas sh /etc/netstart em0  # Reload a single interface

Temporary, runtime changes can be made with ifconfig(8) :

$ doas ifconfig em0 10.0.0.100 255.255.255.0  # Set a temporary IPv4 address

Hostname #

Set the system’s fully qualified domain name in myname(5) (/etc/myname). This replaces scutil --set HostName on macOS.

host.example.com

Reload networking with sh /etc/netstart after changes.

Default gateway #

Set the default gateway(s) in mygate(5) (/etc/mygate). One address per line; the first of each family is used.

192.0.2.1
2001:db8:6000:9344::1

Reload networking with sh /etc/netstart.

DNS resolvers #

Configure resolvers in resolv.conf(5) , rather than using scutil --dns or the System Settings UI:

nameserver 192.0.2.1
lookup file bind

Reload networking with sh /etc/netstart.

Daemons and startup #

macOS uses launchd and launchctl for service management. OpenBSD uses the traditional BSD init and rc system; see init(8) , rc(8) , and rc.conf(8) . System defaults are in /etc/rc.conf. Do not edit it directly; override and localize settings in /etc/rc.conf.local.

Control and enable daemons with rcctl(8) . For example, to manage the base web server, httpd(8) :

$ doas rcctl start httpd    # Start httpd now (analogous to `launchctl kickstart`)
$ doas rcctl stop httpd     # Stop httpd (analogous to unloading a launchd service)
$ doas rcctl reload httpd   # Reload httpd configuration
$ doas rcctl enable httpd   # Enable start at boot (persistent)
$ doas rcctl disable httpd  # Disable start at boot

Common equivalents #

For further details, consult the referenced manual pages on this site.