Tutorials > linux_server_commands

Warning : this is not a tutorial but more the list of commands I think are useful.

Linux server commands

NUC boot keys

key action
F2 BIOS
F10 Boot menu

Configuration

General

Remove error sounds (it is very annoying on windows)

bind 'set bell-style none'

Base

Setup SSH

sudo apt install openssh-server
sudo ufw allow ssh

TMUX: Terminal multiplexing

sudo apt install tmux

Resume last session :

tmux -a

Copy big files with progress bar

sudo apt install pv
pv sourcefile > destinationfile

Disable GUI

Disable:

sudo systemctl set-default multi-user

Enable:

sudo systemctl set-default graphical

Network adapter priority

Install ifmetric & net-tools:

sudo apt install ifmetric net-tools

Use route to know which interface is the preferred one :

route -n

Note : the lowest metric is the preferred

Update the metrics with ifmetric:

sudo ifmetric wlp0s20f3 50

VNC

Install:

sudo apt install tigervnc-standalone-server

Configure xstartup and paste the code below:

nano ~/.vnc/xstartup 
#!/bin/sh
# Start Gnome 3 Desktop
export XDG_SESSION_TYPE=x11
[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
#vncconfig -iconic &
dbus-launch --exit-with-session gnome-session &

Create and configure service change arrol by your user name

chmod u+x  ~/.vnc/xstartup 
[Unit]
Description=Start TightVNC server at startup
After=syslog.target network.target

[Service]
Type=forking
User=arrol
Group=arrol
WorkingDirectory=/home/arrol

PIDFile=/home/arrol/.vnc/%H:%i.pid
ExecStartPre=/usr/bin/vncserver -kill :%i > /dev/null 2>&1
ExecStart=/usr/bin/vncserver -localhost no -geometry 1920x1080 :%i
ExecStop=/usr/bin/vncserver -kill :%i

[Install]
WantedBy=multi-user.target

Enable Service

systemctl daemon-reload 
systemctl enable [email protected] 
systemctl start [email protected]

Google Chrome

Install:

cd ~/Downloads
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo dpkg -i google-chrome-stable_current_amd64.deb

Run: 

google-chrome

Mount USB devices

list UDB devices :

sudo fdisk -l

Mount sda1:

sudo mount -t ntfs /dev/sda1 /media/USB

Mount mmcblk0p1 (SD card):

sudo mount -t ntfs /dev/mmcblk0p1 /media/SD

KVM

Check configuration

sudo apt install -y cpu-checker
kvm-ok

Install requirements :

sudo apt install qemu qemu-kvm libvirt-daemon bridge-utils virt-manager virtinst
sudo apt install ovmf ebtables dnsmasq

KVM Linux installation

Just follow the steps, there is no trap :)

KVM windows installation

For windows you first need to download virtio drives (better than standard drivers).

Virtio iso download

You can setup the windows machine and at the end add virtio image ad cd-rom. Once done, install windows normally until you reach the point where it asks you where to install windows, then load drivers from the virtio drive .iso -> viostor -> w10 -> amd64

Then you can install windows on the hard drive.

KVM management

List all VMs (on and off)

virsh list --all

Start VM: 

virsh start machine_name

KVM connection :

Download and install virt-manager

You can connect using your ip address as follow : spice://192.168.1.95:5972

Firewall

Forwarding with iptables

sudo iptables -t nat -I PREROUTING -p tcp -d 192.168.1.95 --dport 3389 -j DNAT --to-destination 192.168.122.59:3389
sudo iptables -I FORWARD -m state -d 192.168.122.0/24 --state NEW,RELATED,ESTABLISHED -j ACCEPT

List iptables rules:

iptables -L

Firewall (firewalld)

Install:

sudo apt install firewalld

Reset configuration :

rm -rf /etc/firewalld/zones/

List configuration :

sudo firewall-cmd --list-all-zones
firewall-cmd --get-active-zones

Reconfigure zones :

sudo firewall-cmd --remove-interface eno1 --zone=public --permanent
sudo firewall-cmd --add-interface eno1 --zone=external --permanent

sudo firewall-cmd --remove-interface virbr0 --zone=public --permanent
sudo firewall-cmd --add-interface virbr0 --zone=trusted --permanent

sudo firewall-cmd --remove-interface wlp0s20f3 --zone=public --permanent
sudo firewall-cmd --add-interface wlp0s20f3 --zone=external --permanent

sudo firewall-cmd --reload

Open ports

The ssh port is opened by default

sudo firewall-cmd --zone=external --permanent --add-port=5901/tcp
sudo firewall-cmd --reload

Open ports:

sudo firewall-cmd --zone=external --permanent --add-port=10022/tcp
sudo firewall-cmd --reload

sudo firewall-cmd --zone=external --permanent --add-port=5971/tcp
sudo firewall-cmd --reload

sudo firewall-cmd --zone=external --permanent --add-port=5972/tcp 
sudo firewall-cmd --reload

Forward ports ports:

# forward and whitelist ssh port
sudo firewall-cmd --add-forward-port=port=10022:proto=tcp:toport=22:toaddr=192.168.122.21 --zone=external --permanent
sudo firewall-cmd --add-port=10022/tcp --zone=external --permanent
sudo firewall-cmd --reload

# forward and whitelist VNC port
sudo firewall-cmd --add-forward-port=port=5973:proto=tcp:toport=5971:toaddr=192.168.122.21 --zone=external --permanent
sudo firewall-cmd --add-port=5973/tcp --zone=external --permanent
sudo firewall-cmd --reload

# forward and whitelist other port
sudo firewall-cmd --add-forward-port=port=5982:proto=tcp:toport=5982:toaddr=192.168.122.21 --zone=external --permanent
sudo firewall-cmd --add-port=5982/tcp --zone=external --permanent
sudo firewall-cmd --reload

Config file is : /etc/firewalld/direct.xml

Some other commands :

sudo firewall-cmd --permanent --remove-port=3389/tcp
sudo systemctl restart firewalld
sudo systemctl stop firewalld
sudo firewall-cmd --list-all
sudo firewall-cmd --state
sudo firewall-cmd --reload

Modify ssh port

Edit port line in

nano /etc/ssh/sshd_config

Connect using new port:

ssh [email protected] -p new_port

Secure SSH with fail2ban

Install :

apt-get install fail2ban

Backup configuration:

cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.conf.backup

Edit configuration as you wish :

nano /etc/fail2ban/jail.conf

Restart Service:

/etc/init.d/fail2ban restart

VPN

Download:

cd ~/Downloads
wget https://git.io/vpn -O openvpn-ubuntu-install.sh

Make executable:

chmod -v +x openvpn-ubuntu-install.sh

Install :

sudo ./openvpn-ubuntu-install.sh

Just follow the steps :)

Service commands:

sudo systemctl stop  [email protected]
sudo systemctl start  [email protected]
sudo systemctl status  [email protected]

To uninstall / edit configuration just start the openvpn-ubuntu-install.sh again !

Monitor performances

Install:

sudo apt-get install htop
sudo apt-get install lm-sensors

Run:

htop
sensors