Eric Radman : a Journal

An OpenBSD Workstation

The most important feature of any workstation is getting a terminal that is pleasant to use. By default most terminals render text with a heavier weight than I would like. To solve this select a font with a light or book variation. Here is my invocation for the simple terminal

st -f 'Hermit:light:pixelsize=14:antialias=true:autohint=true'

My st port includes

The really compelling feature of st is that it automatically substitutes glyphs from the default font if the one you've selected does not contain them. This enables me to use the really excellent Hermit font while retaining the extended character set of DejaVu Sans.

utf-8 and colors

To ensure you get full Unicode support from applications such as mutt or tmux set your language type using

LC_CTYPE=en_US.UTF-8
export LC_CTYPE

Suspend & Resume

zzz and ZZZ are shortcuts for suspend and hibernate if apmd is run at startup. The -A flag will automatically scale the CPU frequency to save power.

Another feature of apmd(8) is to react to a low battery by hibernating or sleeping. This change to rc.conf.local reacts to a battery level of 8% or less

apmd_flags="-A -Z 8"

X Configuration: .xsession

xset -b

while true; do
    batt="$(sysctl -n hw.sensors.acpibat0.watthour3 | cut -f1,2 -d" ")"
    xsetroot -name "$batt"
    sleep 60
done &
xsetroot -solid gray40
exec dwm

xset -b disables the annoying beep that terminals sometimes make.

I run a loop in the background that read the available battery life (Wh) and updates the window manager's display area. Any sensor data can be included in such output.

Finally set the background color and start your favorite window manager.

Switch to an External Monitor

As far as I know, OpenBSD does not have a native way of reacting to display plug events. When connecting an external monitor I run a little script to adjust the display

 #!/bin/sh
 xrandr --output DP-1 --auto --primary
 xrandr --output eDP-1 --off
 xrandr --output HDMI-1 --off

Where eDP-1 is the LCD pannel on my laptop.

tmux

There's only a few tweaks I make to my terminal multiplexor's configuration. I frequently run entr in a smaller pane on the bottom

bind-key C-t split-window -p 25

I don't know of a terminal color picker, but they can be printed with a shell loop.

#!/bin/ksh

for i in `jot 255`; do
  printf "\033[38;5;${i}mcolour${i}\n"
done

Then I set status background and active border to bright green

set -g status-bg colour118
set -g pane-active-border-fg colour118
set -g pane-border-fg colour30

Most importantly, clean up the status bar so that only the window names are displayed:

# remove status debris
set -g status-left ''
set -g status-right ''

Using Disk Encryption

OpenBSD provides software RAID by way of a virtual host bus adapter called softraid0. This HBA is also used for setting up disk encryption. To set use a disklabel (in my case for sd0g /home set the partition type to RAID

# disklabel -E /dev/sd0c
Label editor (enter '?' for help at any prompt)
/dev/sd0c> m
partition to modify: [] l
offset: [141362304]
size: [358755776]
FS type: [4.2BSD] RAID
/dev/sd0c*> q
Write new label?: [y]

Now configure it for crypto using -c C

# bioctl -c C -l /dev/sd0j softraid0
New passphrase:
Re-type passphrase:
softraid0: CRYPTO volume attached as sd1

Mount it using the same command. The kernel log will show a new virtual device appear

sd1 at scsibus3 targ 1 lun 0: <OPENBSD, SR CRYPTO, 006>
sd1: 175173MB, 512 bytes/sector, 358755248 sectors

Now add a disklabel and format the encrypted volume

$ doas disklabel -E /dev/sd1c
$ doas newfs /dev/rsd1a

Devices in OpenBSD may be mounted by device name or by disklabel UID which is a random id generated when the label is created.

$ disklabel /dev/sd1c | grep uid
duid: 5005bf4c398ff7b9

It's this ID that we'll to mount the volume, in this way plugging in other drives won't confuse mount after we prompt the user for a password on boot. Adding the following to rc.local will ask for a password four times before giving up

#/etc/rc.local
for attept in 1 2 3 4; do
  bioctl -c C -l 6bce88736e499a49.j softraid0 && break
  sleep 1
done
fsck -y 5005bf4c398ff7b9.a
mount -o nodev,nosuid,softdep,wxallowed 5005bf4c398ff7b9.a /home

That last mount parameter wxallowed is important because it will allow you to run certain interpreters such as Python from a virtualenv in your home directory.

If you would like to enable crypto on the entire boot volume see this post by Ted Unangst.

Reducing Password Fatique with YubiKey

Yubico makes a nice little hardware key that, among other things, can be used to generate one time passwords for user authentication. The yubikey-personalization-gui is a Qt-based program that can be used to write private keys to one of two "slots". Copy the 12-digit private identity and the 32-digit secret key without spaces to like so

echo "5c e1 e0 3e 63 a4" | tr -d ' ' > /var/db/yubikey/$USER.uid
echo "57 e3 af 3e 9b 51 2b 10 58 7d 33 fb d9 08 ef 7b" | tr -d ' ' > /var/db/yubikey/$USER.key

It is also important to have the right permissions. If you are running X be sure to change the owner of each key to match it's owner so that screen lock programs can authenticate

chmod 600 /var/db/yubikey/$USER.{key,uid}
chown $USER /var/db/yubikey/$USER.{key,uid}

Now set YubiKey as the authentication method for the group staff by editing /etc/login.conf

- :tc=auth-defaults:
+ :auth=yubikey

If you're a long-time BSD user you might be tempted to run cap_mkdb to rebuild the login DB. You don't need to do this; in fact the new .db file will override local changes to /etc/login.conf.

Screen Lock

Add the following to your .xsession to automatically lock the screen after 5 minutes of activity

xidle -ne -delay 1 -timeout 7200 -program /usr/local/bin/slock &

To trigger this action when the system is suspended, create /etc/apm/suspend with an instruction to signal xidle to run the lock program

#!/bin/sh
pkill -USR1 xidle

Switching Networks

One thing that might not be obvious on BSD is how to switch from one network to another. When switching from wireless to wired for example. First, remove any IP addresses and set the interface down.

ifconfig wpi0 -inet down

Removing the IP address from an interface also drops any link-local or so-called "connected" routes. It may be helpful to nuke all routes.

route -n flush

-n prevents route from trying to resolve hostnames.

If you have set up WPA on your wireless card you can likewise remove the network parameters to obtain a broadcast SSID

 ifconfig wpi0 nwid "Mobile Hotspot" wpa wpakey 09123456789
 ifconfig wpi0 -nwid -wpa -wpakey # use broadcast id

Kerberos

If your workplace uses Kerberos there is a good chance that they provide the list of KDC servers via DNS SRV records

$ host -t srv _kerberos._udp.eradman.com

Heimdal Kerberos will do this lookup automatically. A basic configuration for /etc/heimdal/krb5.conf appears as such

 [libdefaults]
     ignore_acceptor_hostname = true
     rdns = false
     default_realm = ERADMAN.COM

 [realms]
     ERADMAN.COM = {
             default_domain = ERADMAN.COM
     }

 [domain_realm]
 .ERADMAN.COM = ERADMAN.COM
 ERADMAN.COM = ERADMAN.COM

Now get a ticket

$ kinit
radman@ERADMAN.COM's Password: *********
$ klist
Credentials cache: FILE:/tmp/krb5cc_1000
        Principal: eradman@ERADMAN.COM

  Issued                Expires               Principal
Oct 31 10:02:30 2017  Oct 31 20:02:30 2017  krbtgt/ERADMAN.COM@ERADMAN.COM

Firefox

To enable Firefox to pick use Kerberos we need to point it to the GSSAPI library from the heimdal package. For automated configuration this means installing /usr/local/lib/firefox/browser/defaults/preferences/openbsd.js

pref("network.negotiate-auth.allow-non-fqdn", true);
pref("network.negotiate-auth.gsslib", "/usr/local/heimdal/lib/libgssapi.so.9.0");
pref("network.negotiate-auth.trusted-uris", "eradman.com");
pref("network.negotiate-auth.using-native-gsslib", false);

Since the OpenBSD build of Firefox is patched to use unveil(2), add an entry to /etc/firefox/unveil.main for allowing read of the Heimdal shared libraries

# kerberos
/usr/lib r
/usr/local/heimdal/lib r

# home directory
~/ rwc

Chromium

Chromium is not built with Kerberos support on OpenBSD, but it can be added by modifying /usr/ports/www/chromium/Makefile

120c120
<    use_kerberos=false \
-
>    use_kerberos=true \
131
<    extra_cppflags=\"-idirafter ... \"
-
>    extra_cppflags=\"-idirafter /usr/local/heimdal/include ... \"

Run make install and a mere 24 hours later the build should be complete. A policy file can be applied for installing the file /etc/chromium/policies/managed/openbsd.json

{
  "AuthServerWhitelist": "*.eradman.com",
  "GSSAPILibraryName": "/usr/local/heimdal/lib/libgssapi.so.9.0"
}

The OpenBSD build of Chromium is patched to use unveil(2), add an entry to /etc/chromium/unveil.main

# kerberos
/usr/local/heimdal/lib r
/usr/lib r

# home directory
~/ rwc

As well as /etc/chromium/unveil.utility_network

# kerberos
/usr/local/heimdal/lib r
/usr/local/lib r
/usr/lib r

After installing this file, navigate to chrome://policy to see if all settings applied.

Also be sure to raise the limit for open files for the group staff by editing /etc/login.conf

:openfiles-max=16384:\
:openfiles-cur=8192:\

Power Settings

Lid Behavior

On laptops the default beahvior is to sleep when the lid is closed. Disable this by setting machdep.lidaction=0 or machdep.lidaction=2 to hibernate instad.

Last updated on May 28, 2020