Some of ubuntu command

Firewall

---

using ufw firewall (Uncomplicated Firewall)

Install UFW

sudo apt-get install ufw

See the Firewall Status UFW

sudo ufw status
sudo ufw status verbose

See the Firewall Status UFW

sudo ufw status
sudo ufw status verbose

Block Specific IP & port UFW

sudo ufw deny from {ip-address-here} to any port {port-number-here}

Enable/Disable UFW

sudo ufw enable/disable

Configure UFW

sudo ufw allow ssh #allow ssh
sudo ufw allow 25 #allow port
sudo ufw default deny incoming #set default to deny
sudo ufw default allow outgoing #set default to allow
sudo ufw delete allow ssh #delete allow port/service
sudo ufw reset #ufw reset rules

UFW delete Nubered role

sudo ufw status numbered
sudo ufw delete {number}

SSH Server

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Install SSH Server

sudo apt install openssh-server

Check SSH Status

systemctl status ssh

Starting SSH/Stopping SSH

systemctl stop/start ssh

SSH service to start during system boot run:

systemctl enable/disable ssh

Configure SSH

nano /etc/ssh/sshd_config

Reload SSH

service ssh reload

VPNSERVER

---

Softether

Instalation

OpenVPN

Instalation

HAPROXY

---

Load balancing & Routing

Install Haproxy

apt-get install haproxy

Setting Haproxy

sudo nano /etc/haproxy/haproxy.cfg

Restart Haproxy

systemctl restart haproxy.service

Kill Process

---

Kill process running under certain port:

sudo fuser -k -n tcp 8000

Services

---

Service Commands

Use the service command (Requires sudo)

service ssh status      (service status)
service --status-all    (all services status)

Almost every service has the following commands, some may have more like apache graceful-restart:

service servicename start
service servicename stop
service servicename restart
service servicename status
service servicename force-reload

Autostart

Add Service links:

sudo update-rc.d servicename defaults

Whether you get a warning if they already exist or not, enable it now:

sudo update-rc.d servicename enable

Remove Autostart

Pass the Force flag

sudo update-rc.d -f servicename remove

Autostart Daemons

There is are several startup popular daemons:

• CentOS uses SystemV
• Ubuntu 14 uses Upstart
• Ubuntu 14.10+ uses SystemD (15, 16, 17..)

Focus on SystemD.

SystemD Commands

This would only apply to Ubuntu 14.10+, otherwise you would use Upstart.

systemctl     <-- You'll use this more often 
journalctl    <-- You'll use this more often
update-rc.d   <-- You'll use this more often
                  --------------------------
                  Installs/Removes System-V style init script links
                  Note: System-V Style, but it's really SystemD. (Confusing huh?)

                  "NNname" is the runlevel, lower means startup sooner
                  ----------------------------------------------------
                  The Location is: /etc/rcrunlevel.d/NNname  
                  The Target is:   /etc/init.d/name.
notify 
analyze 
cgis 
cgtop 
loginctl 
nspawn

Shutdown

---

shutdown
reboot
shutdown -h now
shutdown -h +10     (shutdown 10 mins)
shutdown -r now     (reboot now)

Compress/UnCompress

---

Uncompress

gzip -dvk file.txt.gz     
bzip2 -d file.txt.bz2
tar -xvf file.tar
tar -zxvf file.tar.gz
unzip test.zip

Compress

gzip -vk file.txt                   (Creates file.txt.gz)
bzip2 file.txt                      (Creates  file.txt.bz2)
tar -cvf file.tar file.txt          (Creates tar)
tar -czvf file.tar.gz file.txt      (Creates tar.gz)
zip filename.zip file.txt           (Creates filename.zip)
zip -r folder.zip path/to/folder    (Creates  folder.txt.bz2)

Running Process on Background

---

Using TMUX on ssh terminal

tmux #start this on SSH Terminal
tmux attach #open tmux session
exit #close tmux

Checking Information

---

Check cpu information

1. /proc/cpuinfo
2. lscpu
3. hardinfo

Switch User on Terminal

---

Check current user

whoami

Check current user

su -u [username]
ex:
su -u User2 zsh

Network

---

Check IP

ifconfig

Change Routing Table

sudo ip route add IP_VPN via "Current Gateway" dev wlan0
sudo ip route del default via "Current Gateway" dev wlan0
sudo ip route add default via "Gateway VPN" dev vpn
ip route show