NETWORKING

WiFi

Use WiFi without a separate network manager with this simple guide. Needs "dhcpcd" or "dhcpclient", "net-tools" or "iproute2", "wpa_supplicant", and the WiFi drivers for your wireless card (like "iwlwifi" and its "ucode"), which in part can be installed from a package usually named "linux-firmware", but they may not be complete (this provides "ucode" but not "iwlwifi").
NOTE: The "<DEVICE_NAME>" can be either "wlp3s0" or "wlan0". Change accordingly the following commands to suit your needs.

Create the configuration file (as "root", not "sudo"):
wpa_passphrase <NETWORK_NAME> <PASSWORD> > /etc/wpa_supplicant.conf
Delete non hashed password from "/etc/wpa_supplicant.conf", but not the hashed one.

Each time you need to connect type the following command (as "root" or with "sudo"):

EXAMPLE 1: With "net-tools" and "dhcpcd":

ifconfig <DEVICE_NAME> down
ifconfig <DEVICE_NAME> up
wpa_supplicant -B -i<DEVICE_NAME> -c /etc/wpa_supplicant.conf -Dwext
dhcpcd <DEVICE_NAME>

EXAMPLE 2: With "iproute2" and "dhclient":

ip link set <DEVICE_NAME> down
ip link set <DEVICE_NAME> up
wpa_supplicant -B -i<DEVICE_NAME> -c /etc/wpa_supplicant.conf -Dwext
dhclient <DEVICE_NAME>

You can save either example in a script to activate the Wi-Fi whenever you want.

Note: As an educational tip, the name of a network is also called "SSID" in other places.

ufw

sudo ufw status
sudo ufw enable
sudo ufw disable
sudo ufw default deny
sudo ufw default allow
sudo ufw allow PORT_NUMBER

delete a rule
sudo ufw delete allow PORT_NUMBER
allow everything for a specific address
sudo ufw allow from IP_ADDRESS
allow a specific port for a specific address
sudo ufw allow from IP_ADDRESS to any port PORT_NUMBER

tcpdump

dump all
sudo tcpdump
dump 5 packets
sudo tcpdump -c 5
dump in ASCii format
sudo tcpdump -A
dump in hexadecimal format
sudo tcpdump -xx
dump from an specific interface
sudo tcpdump -i INTERFACE_NAME
dump from a specific port
sudo tcpdump port PORT_NUMBER
dump 5 packets in hexadecimal from an specific interface and a specific port
sudo tcpdump -c 5 -xx -i INTERFACE port PORT_NUMBER

netstat

show routing table, including gateway
netstat -nr
show all ports
netstat -tulpn
show network usage of devices
netstat -i
show active connections
netstat -ta
show active connections, but show ip addresses instead
netstat -tan

traceroute

show which route your connection takes between your computer to the destination
traceroute WEBNAME_OR_IP

nmap

scan a specific ip address (including devices)
nmap IP_NUMBER
scan a specific website
nmap WEBSITE_NAME
scan a specific ip address (including devices) with more information
nmap -v IP_NUMBER
scan two ip address (including devices), 192.168.0.1 and 192.168.0.54
nmap 192.168.0.1,54
scan a range of ip address (including devices), from 192.168.0.1 to 192.168.0.100
nmap 192.168.0.1-100
scan all ip address (including devices) from network 192.168.0.0
nmap 192.168.0.*
scan address from a file
nmap -il <FILE>
scan address and identify OS and running services
nmap -A IP_NUMBER
check if target is up
nmap -sP IP_NUMBER
check reason for services states
nmap --reason IP_NUMBER
show host interfaces
nmap --iflist IP_NUMBER

SSH

login to remote host
ssh ADDRESS
login to remote host as user USER
ssh USER@ADDRESS
set ssh server configuration in /etc/ssh/sshd_config

Port 22 # default port
PermitRootLogin without-password # change "without-password" to "no"
AllowUsers USER_NAME # by allowing a specific user it restricts the others

restart "ssh" service to activate changes

/etc/network/interfaces

# use last 8 octets for hosts
255.255.255.0

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