OpenBSD manual page server

Starting out

This document attempts to list items for the system administrator to check and set up after the installation and first complete boot of the system. The idea is to create a list of items that can be checked off so that you have a warm fuzzy feeling that something obvious has not been missed. A basic knowledge of UNIX is assumed, otherwise type:

Complete instructions for correcting and fixing items are not provided. There are manual pages and other methodologies available for doing that. For example, to view the man page for the ls(1) command, type:

Administrators will rapidly become more familiar with OpenBSD if they get used to using the high quality manual pages.

Some base programs and subsystems also come with sample configuration files in /etc/examples.

Errata

By the time that you have installed your system, it is possible that bugs in the release have been found. Security or reliability fixes can be found at https://www.openbsd.org/errata.html. Binary updates are made available for some architectures and can be installed using syspatch(8).

Login

Log in on the console, or over the network using ssh(1). For security reasons, it is bad practice to log in as root during regular use and maintenance of the system. Instead, administrators are encouraged to add a “regular” user, add said user to the “wheel” group, then use the su(1) and doas(1) commands when root privileges are required.

The installation process provides an option to set up a user account. By default, accounts created via this method are automatically added to the “wheel” group. If that option was not used, see the paragraph Add new users below.

To deny root logins over the network, edit the /etc/ssh/sshd_config file and set PermitRootLogin to “no” (see sshd_config(5)).

Root password

Change the password for the root user. (Note that throughout the documentation, the term “superuser” is a synonym for the root user.) Choose a password that has digits and special characters as well as from the upper and lower case alphabet. Do not choose any word in any language. It is common for an intruder to use dictionary attacks. Type the following command to change it:

To avoid the possibility of rogue files placed in the superuser's PATH, it should never contain the current directory (“.”).

System date

ntpd(8) is used to automatically synchronize clocks with remote NTP servers. You can use ntpctl(8) to check the status. To change the NTP server, see ntpd.conf(5).

Check the system date with the date(1) command. If needed, change the date, and/or change the symbolic link of /etc/localtime to the correct time zone in the /usr/share/zoneinfo directory.

Examples:

Set the current date to January 27th, 2016 3:04pm:

Set the time zone to Atlantic Standard Time:

Check hostname

Use the hostname command to verify that the name of your machine is correct. See the man page for hostname(1) if it needs to be changed. You will also need to edit the /etc/myname file to have it stick around for the next reboot.

Verify network interface configuration and routing tables

The first thing to do is an ifconfig -a to see if the network interfaces are properly configured. Correct by editing /etc/hostname.interface (where interface is the interface name or link layer address, e.g., “em0”) and then using ifconfig(8) to manually configure it if you do not wish to reboot. Read the hostname.if(5) man page for more information on the format of /etc/hostname.interface files and instructions on configuring dynamic addresses.

Routing tables are manipulated using route(8). They can be viewed by issuing “route -n show”. The default gateway address is stored in the mygate(5) file. If you need to edit this file, a painless way to reconfigure the network afterwards is route flush followed by a sh -x /etc/netstart command. Or, you may prefer to manually configure using a series of route add and route delete commands.

Packets are not forwarded by default, due to RFC requirements. If you wish to route packets between interfaces, add one or both of the following directives (depending on whether IPv4 or IPv6 routing is required) to sysctl.conf(5):

See multicast(4) for instructions on configuring multicast routing.

Check DNS

Use host(1) or dig(1) to check that domain name resolution is working properly.

Most likely, the IP address of at least one domain name server was added to resolv.conf(5) while installing the system. resolvd(8) maintains /etc/resolv.conf at runtime.

A hosts(5) file can be used if there is a need for system specific name resolution entries.

Check disk mounts

Check that the disks are mounted correctly by comparing the /etc/fstab file against the output of the mount(8) and df(1) commands. Example:

# cat /etc/fstab
/dev/sd0a / ffs rw 1 1
/dev/sd0d /usr ffs rw,nodev 1 2
/dev/sd0e /var ffs rw,nodev,nosuid 1 3
/dev/sd0g /tmp ffs rw,nodev,nosuid 1 4
/dev/sd0h /home ffs rw,nodev,nosuid 1 5

# mount
/dev/sd0a on / type ffs (local)
/dev/sd0d on /usr type ffs (local, nodev)
/dev/sd0e on /var type ffs (local, nodev, nosuid)
/dev/sd0g on /tmp type ffs (local, nodev, nosuid)
/dev/sd0h on /home type ffs (local, nodev, nosuid)

# df
Filesystem  1024-blocks     Used    Avail Capacity  Mounted on
/dev/sd0a         22311    14589     6606    69%    /
/dev/sd0d        203399   150221    43008    78%    /usr
/dev/sd0e         10447      682     9242     7%    /var
/dev/sd0g         18823        2    17879     0%    /tmp
/dev/sd0h          7519     5255     1888    74%    /home

# pstat -s
Device      512-blocks     Used    Avail Capacity  Priority
/dev/sd0b       131072    84656    46416    65%    0

Edit /etc/fstab and use the mount(8) and umount(8) commands as appropriate. Refer to the above example and fstab(5) for information on the format of this file.

You may wish to do NFS partitions now too, or you can do them later.

Check the running system

You can use ps(1), netstat(1), and fstat(1) to check on running processes, network connections, and opened files, respectively.

Add new users

Add users. There is an adduser(8) script. You may use vipw(8) to add users to the /etc/passwd file and edit /etc/group by hand to add new groups. You may also wish to edit /etc/login.conf and tune some of the limits documented in login.conf(5). The manual page for su(1) tells you to make sure to put people in the ‘wheel’ group if they need root access. For example:

System command scripts

The /etc/rc.* scripts are invoked at boot time, after single-user mode has exited, and at shutdown. The whole process is controlled, more or less, by the master script /etc/rc. This script should not be changed by administrators.

/etc/rc is in turn influenced by the configuration variables present in /etc/rc.conf. Again, this script should not be changed by administrators: site-specific changes should be made to (freshly created if necessary) /etc/rc.conf.local or by using the rcctl(8) utility.

Any commands which should be run before the system sets its secure level should be made to /etc/rc.securelevel, and commands to be run after the system sets its secure level should be made to /etc/rc.local. Commands to be run before system shutdown should be set in /etc/rc.shutdown.

For more information about system startup/shutdown files, see rc(8), rc.conf(8), securelevel(7), and rc.shutdown(8).

If you've installed X, you may want to turn on xenodm(1), the X Display Manager. To do this, change the value of xenodm_flags in /etc/rc.conf.local.

Set keyboard type

Some architectures permit keyboard type control. Use the kbd(8) command to change the keyboard encoding. kbd -l will list all available encodings. kbd xxx will select the xxx encoding. Store the encoding in /etc/kbdtype to make sure it is set automatically at boot time.

Printers

Edit /etc/printcap and /etc/hosts.lpd to get any printers set up. Consult lpd(8) and printcap(5) if needed.

Audio and video recording

The audio(4) and video(4) drivers by default record only silence and blanked images. Normal recording can be enabled by adding the following directives to sysctl.conf(5):

kern.audio.record=1
kern.video.record=1

Power management

If the BIOS supports it, apmd(8) can be configured to act on different events and adjust device performance. In the following example it is configured to start on boot in automatic performance adjustment mode and suspend the system if no AC is connected and the estimated battery life is equal or below 15%:

# rcctl set apmd status on
# rcctl set apmd flags -A -z 15

Mail aliases

Edit /etc/mail/aliases and set the three standard aliases to go to either a mailing list, or the system administrator.

# Well-known aliases -- these should be filled in!
root:		sysadm
manager:	root
dumper:		root

Mail

The default mail agent on OpenBSD is smtpd(8). Details on how to configure an alternative mailer are documented in mailer.conf(5).

OpenBSD ships with a default /etc/mail/smtpd.conf file that will work for simple installations. See smtpd.conf(5) for information on configuring more complex setups. For the default installation, smtpd(8) is configured to only accept connections from the local host. This makes it possible to send mail locally, but not receive mail from remote servers, which is ideal if you have one central incoming mail machine and several clients. To cause smtpd to accept external network connections, modify the listen on directive in /etc/mail/smtpd.conf to include the interfaces to listen on.

Daily, weekly, monthly scripts

Review daily(8) to understand what the periodic system maintenance scripts do and how to customize them: For example, to enable ROOTBACKUP or to add local maintenance code to /etc/daily.local, /etc/weekly.local, or /etc/monthly.local.

Tighten up security

You might wish to tighten up security more by editing /etc/fbtab as when installing X. Look at the other files in /etc and edit them as needed. (Do not edit files ending in .db — like pwd.db, spwd.db, nor localtime, nor rmt, nor any directories.)

Crontab (background running processes)

Check what is running by typing crontab -l as root and see if anything unexpected is present. Do you need anything else? Do you wish to change things? See crontab(5).

Next day cleanup

After the first night's security(8) run, change ownerships and permissions on files, directories, and devices; root may have received mail with subject: "<hostname> daily insecurity output". This mail contains a set of security recommendations, presented as a list looking something like this:

var/mail:
        permissions (0755, 0775)
etc/daily:
        user (0, 3)

The best bet is to follow the advice in that list. The recommended setting is the first item in parentheses, while the current setting is the second one. This list is generated by mtree(8) using /etc/mtree/special. Use chmod(1), chgrp(1), and chown(8) as needed.

Daemons

Enable/disable any daemon processes as necessary. intro(8) contains a comprehensive guide to the various daemons available on the OpenBSD system.

Packages

Install your own packages. The OpenBSD ports collection includes a large set of third-party software. Most of it is available as binary packages that you can install using pkg_add(1). See packages(7) for more details. To start daemons installed from packages, see rc.d(8).

There is also other third-party software that is available in source form only, either because it has not been ported to OpenBSD yet, or because licensing restrictions make binary redistribution impossible. Sometimes checking the mailing lists for past problems that people have encountered will result in a fix posted.

Compiling a kernel

Information on building and modifying kernels is contained within config(8).