Intro

This is a basic Linux firewall program.

Look at your firewalls:

1iptables -L

We see the output of input, output and forwarding rules.

Forward

I don't need any forwarding, so I'm going to drop all forwarding:

1iptables -P FORWARD DROP

Input

Let's 'A'dd, or 'A'ppend a rule with -A. Let's drop all input from a …

Jenkins on Void

Jenkins is janky.

Start

Start the service file.

1sudo ln -s /etc/sv/jenkins /var/service
2sudo sv start jenkins

Then visit the web interface with $BROWSER localhost:8080.

If it's not working, try running the command from the run file the first time:

1chpst -u jenkins java -jar /opt/jenkins/jenkins.war …

See a running log of all system messages:

1journalctl -f

Or just one user:

1journalctl --user -f

Or just one unit (sshd):

1journalctl -f -u sshd

Find errors since November

1journalctl --since=2018-11-01 --grep="EXT4-fs error"

Limit size to 2G.

1journalctl --vacuum-size=2G

Log the fact that you've installed your …

• asciiquarium
• cbonsai -lim "$(fortune)"

1cow=$(cowsay -l | sort -R | head  -1)
2fortune -s | figlet | cowsay -nf $cow | lolcat

Living Space

Kernel modules live in lib/modules/$(uname -r)

Change

Load them with

1sudo modprobe ath9k

Or remove one with

1sudo modprove uvcvideo

The PC's irritating speaker beep can be really annoying. Disable it with:

1sudo modprobe -r pcspeaker

Permanently disable a module by blacklisting it in /etc/modprobe.d:

1 …

Check which kernet modules are loaded into memory

1sudo /sbin/lsmod 

Check which virtual box modules are loaded into memory

1sudo /sbin/lsmod | grep vbox 

Virtual box is using vboxpci, vboxnetadp, vboxnetflt, vboxdr.

Look at what's claiming wifi:

1sudo lshw -C network

If this shows that the device is 'unclaimed' then …

Set Layout with X Display

Set layout to British English.

1setxkbmap -layout gb

Or Polish with:

1setxkbmap -layout pl

Set 'alt + shift', as the command which cycles …

Get the basic config:

1mkdir ~/.config/khard

1cp /usr/share/doc/khard/examples/khard/khard.conf.example ~/.config/khard.conf

Short list

1khard list

Longer list

1khard show

Show from addressbook 'work'

1khard list -a work

Make a new contact in address book 'family'

1khard new -a family

1khard edit grampa

1khard remove …

If you want to kill a program in a graphical environment, open a terminal and type:

Graphical Programs

1xkill

Then click on the application which you want to kill.

All Programs

To kill a program, find it with:

1pgrep discord

This will give you the UUID, e.g. 19643.

Kill the program with:

1kill 19643

Types of Kill

To …

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Config File

If you don't have a …