http://enos.itcollege.ee/~edmund/osadmin/eng/labs/

codeshare.io/c11

OSadmin labs
------------
ISOs can be downloaded:
http://upload.itcollege.ee/edmund/iso/Ubuntu/

OVA files (preinstalled VMs):
http://upload.itcollege.ee/edmund/ova/
when importing, please reinitialize MAC-address

server install:
http://enos.itcollege.ee/~edmund/osadmin/est/praktikumid/OSadmin-ubuntu-server-install.pdf

desktop install:
http://enos.itcollege.ee/~edmund/osadmin/est/praktikumid/OSadmin-ubuntu-server-install.pdf

download at CLI:
wget (or curl)
wget http://upload.itcollege.ee/edmund/iso/Ubuntu/ubuntu-16.04.1-server-amd64.iso

please check also checksums!
http://upload.itcollege.ee/edmund/iso/ISO-checking.html


ubuntu-16.04.1-server-amd64.iso
ubuntu-mate-16.04.1-desktop-amd64.iso
+ appropriate checksums


/home/edmund/VirtualBox VMs
/shared/linux/edmund/VirtualBox VMs
bind mount
http://unix.stackexchange.com/questions/198590/what-is-a-bind-mount

https://en.wikipedia.org/wiki/Binary_prefix

https://www.virtualbox.org/wiki/Documentation
-> End-user documentation
https://www.virtualbox.org/manual/UserManual.html

virtual networking
https://www.virtualbox.org/manual/ch06.html

Ubuntu
https://help.ubuntu.com/community/BootOptions
http://www.memtest.org/

hostname: server
user/psw: student

partition table type:
MBR (dos) - 4 primary partitions
/dev/sda1..4 - primary partitions

OR
3 primary + 1 extended with 1...128 logical volumes
/dev/sda1..3 primary
/dev/sda4 - extended
/dev/sda5... logical volume

GPT - up to 128 partitions (all primary)
https://en.wikipedia.org/wiki/GUID_Partition_Table

https://en.wikipedia.org/wiki/Names_of_large_numbers

https://en.wikipedia.org/wiki/Kernel_(operating_system)
https://www.kernel.org/

# # #

CTRL+L to clean quickly the CLI

scroll the CLI:
SHIFT+PgUp/PgDn

Software updates
sudo -i (become root)

CRON - like scheduled tasks in Windows

switching GUI-CLI:
CTRL+ALT+F1...F6
back:
ALT+F7

in VM:
ALT+arrow keys

update packages database:
sudo apt-get update

https://wiki.ubuntu.com/DevelopmentCodeNames

full upgrade all packages
apt-get dist-upgrade

clean the APT cache (/var/cache/apt/archives/)
sudo apt-get clean

check running kernel:
uname -r

apt is a wrapper of apt-get but some parameters may be different - check the man-pages for more details

after upgrade we have a new version of kernel
we need to update GRUB to announce of new kernel
sudo update-grub

then reboot and ensure that new kernel is in use
uname -r

then remove old kernel(s)
options:
* apt-get autoremove

* apt list --installed | grep linux-image
* apt list --installed | grep linux-header

http://askubuntu.com/questions/17823/how-to-list-all-installed-packages

http://ubuntuhandbook.org/index.php/2016/05/remove-old-kernels-ubuntu-16-04/

some searchers:
list installed package ubuntu

# # #

query DHCP address:
sudo dhclient enp0s8

release:
sudo dhclient -r enp0s8

using key file to log into SSH server:
http://enos.itcollege.ee/~edmund/materials/ssh.txt

we need OpenSSH server to be installed on server at first:
http://www.ewhathow.com/2013/09/how-to-check-if-ssh-is-running-on-linux/

find out whether you have ssh server installed
service --status-all | grep ssh
ps aux | grep ssh
netstat -plant | grep :22

sudo apt update #update database
sudo apt install ssh openssh-blacklist* #install the packages
sudo apt clean #clean the APT cache

search packages online:
http://packages.ubuntu.com/
check codename CLI:
lsb_release -c

# # #

Please log in at (virtual lab system)
https://i-tee.itcollege.ee/

labs are avaliable at http://upload.itcollege.ee/edmund/ova/ as .ova files as well
(please see ubuntu folder)

for rdesktop you can define keyboard:
rdesktop -u<user> -p<password> -N -k et -a16 i-tee.itcollege.ee:<port>

update system:
sudo apt update
sudo apt full-upgrade
sudo apt clean

in case of new kernel:
sudo update-grub
sudo reboot

https://guacamole.incubator.apache.org/doc/gug/using-guacamole.html
challenge: find out a way to copy-paste text directly into VM (virtual machine)

if needed, SSH server configuration file is here:
/etc/ssh/sshd_config

after changing SSH server configuration, restart its service:
sudo service ssh restart

Setting up SSH key-based authentication - http://enos.itcollege.ee/~edmund/materials/ssh.txt

# # #

name resolving
1st step - hosts file
https://en.wikipedia.org/wiki/Hosts_(file)

/etc/hosts
#server IP-alias
172.16.10.1	s1

~/.bash_aliases
# server shell alias
alias s1='ssh student@s1'

run session scripts:
. ~/.bash_aliases
source ~/.bash_aliases

firewall
https://help.ubuntu.com/community/UFW

SSH port:
cat /etc/services | grep ssh

change owner:
chown user:group file

changing interface names
http://enos.itcollege.ee/~edmund/osadmin/materials/net/70-persistent-net.rules

# # #

Quick Access to labs
--------------------
desktop
rdesktop -u<user> -p<password> -N -k et -a16 i-tee.itcollege.ee:9008

server
rdesktop -u<user> -p<password> -N -k et -a16 i-tee.itcollege.ee:9009

user apps ~/.local/share/applications/ (has highest priority)
system-wide /usr/share/applications/

system-wide icons:
/usr/share/icons/
/usr/share/pixmaps/

create a text file ~/.local/share/applications/labs.desktop:
[Desktop Entry]
Name=OSadmin virtual lab
GenericName=OSadmin virtual lab
Comment=OSadmin virtual lab
Exec=sh /full/path/connect-vlab.sh
Terminal=false
Type=Application
Icon=mathomatic
Categories=Network;
StartupNotify=false

make ~/.local/share/applications/labs.desktop executable:
chmod +x ~/.local/share/applications/labs.desktop
more information:
man chmod
http://permissions-calculator.org/


Making shortcut to desktop:
start dragging the icon (*.desktop file)
then hold down ALT-key
choose "create shortcut"
release the mouse left key

# # #

https://wiki.ubuntu.com/Releases


search:
new in kernel 4.10.11
http://www.phoronix.com/scan.php?page=news_item&px=Linux-4.10-Features-So-Far
https://kernelnewbies.org/Linux_4.10

check architecture, CPU:
arch
lscpu

lowlatency ~real time kernel
e.g.
jack audio server (http://www.jackaudio.org/), CNC milling machine (http://linuxcnc.org/) etc
more about audio servers https://en.wikipedia.org/wiki/Sound_server

some aliases:
http://enos.itcollege.ee/~edmund/materials/bash/bash_aliases_root.txt

install new kernel
- download and update http://enos.itcollege.ee/~edmund/osadmin/eng/labs/kernel.sh
- copy it to server:
CLI: scp -i ~/.ssh/keyfile kernel.sh user@host:/home/student/
GUI: use Ubuntu file manager to connect over SSH and copy the file
- create bash alias to run kernel.sh periodically in future

weather in CLI
- see the file http://enos.itcollege.ee/~edmund/osadmin/eng/labs/weather-in-terminal.txt
- when needed, install curl
- weather in:
-- Tallinn Airport: curl wttr.in/tll
-- Tallinn: curl wttr.in/tallinn
- help: curl wttr.in/:help
- create an alias:
-- alias wtr='curl wttr.in/tallinn'

screensaver CLI
Matrix
- install package cmatrix
- run in different modes
-- cmatrix -b
-- cmatrix -s -b

Some more

Termsaver
sudo apt-get install termsave
termsaver matrix
man termsaver

Pipes - seems to not work (can you fix it?)
https://github.com/pipeseroni/pipes.sh

Aquarium
requires modified version of Perl
https://www.ghacks.net/2011/03/02/have-some-linux-ascii-fun-with-asciiquarium/

Some more fun programs:
sl, fortune, lolcat, cowsay, boxes, figlet
see http://enos.itcollege.ee/~edmund/osadmin/eng/labs/fun.sh

see http://enos.itcollege.ee/~edmund/osadmin/eng/labs/environment-variables.txt
create new env variable for user using existing variables

# # #

Disk management
DOS (MBR)
4 pri
OR
3 pri + 1 ext with up to 128 logical volumes

GPT

/dev/sdb
/dev/sdc
/dev/sdd
/dev/sde

pwd
/root

mkdir -p /var/research/"research department"

mkdir -p /var/research/windows /var/research/linux /var/research/mac

chmod 070 /var/research/windows /var/research/linux /var/research/mac

addgroup clippy && addgroup tux && addgroup apple

chown :clippy /var/research/windows && chown :apple /var/research/mac && chown :tux /var/research/linux

chgrp clippy /var/research/windows

adduser --ingroup clippy win
adduser --ingroup tux lin
adduser --ingroup apple mac

modify later:
usermod -g clippy win

partitions:
/dev/sdb1 -> win
/dev/sdc1 -> lin
/dev/sdd1 -> mac
/dev/sde1 -> swap

fdisk, cfdisk, parted

cfdisk /dev/sdb

mkfs

https://help.ubuntu.com/community/hfsplus

apt update && apt install hfsprogs	

make filesystems
mkfs.ntfs /dev/sdb1
mkfs -t ntfs

mounting
ntfs-3g /dev/sdb1 /var/research/windows

mount -t ext4 /dev/sdc1 /var/research/linux

mount -t hfsplus /dev/sdd1 /var/research/mac

/etc/fstab

fsck

getent group clippy: 1001
getent group tux: 1002
getent group apple: 1003


# Change groups, permissions also AFTER mounting file systems
chgrp clippy /var/research/windows
chgrp tux /var/research/linux
chgrp apple /var/research/mac

chmod 070 /var/research/windows /var/research/linux /var/research/mac

nano /etc/fstab
......
UUID=hash /var/research/windows ntfs-3g gid=1001,umask=0707 0 0
UUID=hash /var/research/linux ext4 defaults 0 0
UUID=hash /var/research/mac hfsplus gid=1003,umask=0707 0 0
UUID=hash none swap sw 0 0

replace hash with proper value shown using blkid

mount and check the fstab syntax
mount -a

SWAP
----


make swap:
mkswap /dev/sde1

mount swap:
swapon /dev/sde1

add proper line to /etc/fstab
turn on all swap spaces:
swapon -a

Change umask per user ~/.profile
umask=007

Swappiness
https://askubuntu.com/questions/103915/how-do-i-configure-swappiness
https://en.wikipedia.org/wiki/Swappiness


current value
cat /proc/sys/vm/swappiness
sysctl vm.swappiness

change
sysctl vm.swappiness=10

check:
sysctl vm.swappiness


# # #

monitor certain log file, e.g.
sudo -i
tail -f /var/log/auth.log


###

combine multiple commands:
command1 `command2`
command1 $(command2)


# # #

For SSD disks please use fstrim
by default it is located at /etc/cron.weekly/ folder
you can move it to the /etc/cron.daily/ or even /etc/cron.hourly/ folder depending on your activities

TBW - terabytes to write

some shopping:
https://hakshop.com/
https://www.defcon.org/
https://www.yubico.com/products/yubikey-hardware/