Doas: the Sudo Replacement

Doas for Group Wheel

Normally, you don't want to log in as root for security reasons. OpenBSD does not come with sudo by default; instead, it provides a small, simple utility called doas.

First, let's use su to log in as root:

$ su
Password:

Next, we create /etc/doas.conf using this command:

# echo "permit persist :wheel" >> /etc/doas.conf

This allows any user in the group wheel to run doas. The shell's redirection operator >> appends to the end of a file (or creates it if it does not already exist).

Note: The # sign means you run this command as root by first logging in using su. The $ sign means you run the command as your normal user. Do not literally type # or $.

Afterwards, exit su:

# exit

You could also type ctrl+d to tell the shell you've reached the end-of-file and want to exit.

Next, test the configuration:

$ whoami
user
$ doas whoami
doas (user@user.coconut.ircnow.org) password: 
root

For this configuration, you will need to provide your user password in order to use doas. The persist keyword means that after the password is first provided, doas will not ask again for some time.

Note about redirection

Redirection with > and >> is done by your shell. This means that the command below probably does NOT work:

$ doas echo "permit nopass :wheel" >> /etc/doas.conf
ksh: cannot create /etc/doas.conf: Permission denied

Although echo is run as root, appending to /etc/doas.conf is run as your current non-root user. Since this user probably does not have write permissions to /etc/doas.conf, the command fails.

No password needed

Life is a lot easier when you don't require the user password.

Run doas with the -s argument to get a shell as root, then append to doas.conf:

$ doas -s
# echo "permit nopass :wheel" >> /etc/doas.conf
# exit

The drawback to this configuration is that any user in the wheel group gets complete root access without requiring any password.

Whitelisting users

You can also permit a specific user to have root powers:

# echo "permit nopass user" >> /etc/doas.conf

This allows user to login as root using doas without a password.

Security

You should avoid logging in as root or running programs as root unless absolutely necessary. Running insecure or malicious programs as root can lead to stolen data. If you find yourself using root when you should not need to, chances are you have a bug somewhere else that needs to be fixed.

As a precaution, we should not allow others to read doas.conf:

$ doas chmod o-r /etc/doas.conf