OpenBSD manual page server

Manual Page Search Parameters
AFTERBOOT(8) System Manager's Manual AFTERBOOT(8)

afterboot — things to check after the first complete boot

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:

$ help

Complete instructions for correcting and fixing items is 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:

$ man 1 ls

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

By the time that you have installed your system, it is quite likely that bugs in the release have been found. Any security or reliability fixes can be found at http://www.openbsd.org/errata.html. It is recommended to check this page regularly.

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 sudo(8) 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)).

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 (not space) 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:

$ /usr/bin/sudo /usr/bin/passwd root

It is a good idea to always specify the full path name for the passwd(1), su(1) and sudo(8) commands as this inhibits the possibility of rogue files placed in your PATH being executed for most shells. Furthermore, the superuser's PATH should never contain the current directory (“.”).

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. Alternatively, ntpd(8) can be used to automatically synchronize clocks with remote NTP servers.

Examples:

Set the current date to January 27th, 1999 3:04pm:

# date 199901271504

Set the time zone to Atlantic Standard Time:

# ln -fs /usr/share/zoneinfo/Canada/Atlantic /etc/localtime

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.

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, e.g., “le0”) 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. The loopback interface will look something like:

lo0: flags=8009<UP,LOOPBACK,MULTICAST> mtu 32972
	inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
	inet6 ::1 prefixlen 128
	inet 127.0.0.1 netmask 0xff000000

an Ethernet interface something like:

le0: flags=9863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST>
	inet 192.168.4.52 netmask 0xffffff00 broadcast 192.168.4.255
	inet6 fe80::5ef0:f0f0%le0 prefixlen 64 scopeid 0x1

and a PPP interface something like:

ppp0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST>
        inet 203.3.131.108 --> 198.181.0.253 netmask 0xffff0000

See netstart(8) for instructions on configuring multicast routing.

See hostname.if(5) for instructions on configuring interfaces with DHCP.

Issue a netstat -rn command. The output will look something like:

Routing tables

Internet:
Destination    Gateway           Flags  Refs     Use  Mtu  Interface
default        192.168.4.254     UGS      0 11098028    -  le0
127            127.0.0.1         UGRS     0        0    -  lo0
127.0.0.1      127.0.0.1         UH       3       24    -  lo0
192.168.4      link#1            UC       0        0    -  le0
192.168.4.52   8:0:20:73:b8:4a   UHL      1     6707    -  le0
192.168.4.254  0:60:3e:99:67:ea  UHL      1        0    -  le0

Internet6:
Destination        Gateway       Flags  Refs  Use     Mtu  Interface
::/96              ::1           UGRS     0     0   32972  lo0 =>
::1                ::1           UH       4     0   32972  lo0
::ffff:0.0.0.0/96  ::1           UGRS     0     0   32972  lo0
fc80::/10          ::1           UGRS     0     0   32972  lo0
fe80::/10          ::1           UGRS     0     0   32972  lo0
fe80::%le0/64      link#1        UC       0     0    1500  le0
fe80::%lo0/64      fe80::1%lo0   U        0     0   32972  lo0
ff01::/32          ::1           U        0     0   32972  lo0
ff02::%le0/32      link#1        UC       0     0    1500  le0
ff02::%lo0/32      fe80::1%lo0   UC       0     0   32972  lo0

The default gateway address is stored in the /etc/mygate 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 (see route(8)). If you run dhclient(8) you will have to kill it by running pkill dhclient after you flush the routes.

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 /etc/sysctl.conf:

net.inet.ip.forwarding=1
net.inet6.ip6.forwarding=1

Packets are not forwarded by default, due to RFC requirements.

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. If DHCP is in use, it will overwrite /etc/resolv.conf every time dhclient(8) is run but /etc/resolv.conf.tail can be used to add options and extra name servers to those received dynamically.

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

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.

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

The system should be usable now, but you may wish to do more customizing, such as adding users, etc. Many of the following sections may be skipped if you are not using that package. We suggest that you cd /etc and edit any files in that directory as necessary.

Note that the /etc/motd file is modified by /etc/rc whenever the system is booted. To keep any custom message intact, ensure that you leave two blank lines at the top, or your message will be overwritten.

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 (non-Kerberos). For example:

wheel:*:0:root,myself

Follow instructions for login_krb5(8) if using Kerberos for authentication.

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.

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 xdm(1), the X Display Manager. To do this, change the value of xdm_flags in /etc/rc.conf.local.

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.

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

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

Run newaliases(8) after changes.

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

OpenBSD ships with a default /etc/mail/localhost.cf file that will work for simple installations; it was generated from openbsd-localhost.mc in /usr/share/sendmail/cf. Please see /usr/share/sendmail/README for information on generating your own sendmail configuration files. For the default installation, sendmail 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 sendmail to accept external network connections, modify the sendmail_flags variable in /etc/rc.conf.local to use the /etc/mail/sendmail.cf file in accordance with the comments therein. This file was generated from openbsd-proto.mc.

Note that sendmail now also listens on port 587 by default. This is to implement the RFC 6409 message submission protocol. You may disable this via the no_default_msa option in your sendmail .mc file. See /usr/share/sendmail/README for more information.

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

You might wish to tighten up security more by editing /etc/fbtab as when installing X. In /etc/inetd.conf comment out any extra entries you do not need, and only add things that are really needed.

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.)

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).

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.

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

Install your own packages. The OpenBSD ports collection includes a large set of third-party software. A lot of it is available as binary packages that you can download from ftp://ftp.openbsd.org or a mirror, and install using pkg_add(1). See ports(7) and 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.

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

ksh(1), man(1), pkg_add(1), ps(1), vi(1), hier(7), config(8), dmesg(8), ifconfig(8), intro(8), sudo(8), sysctl(8)

This document first appeared in OpenBSD 2.2.

July 14, 2013 OpenBSD-5.4