https://wiki.debian.org/WiFi/HowToUse#Command_Line

Configure a wireless network (like ifconfig for wireless)

iwconfig                   # by itself, or...
iwconfig [interface name]  # designate specific wireless interface

Shows:

1. The name of the MAC protocol used
2. ESSID (Network Name)
3. The NWID
4. The frequency (or channel)
5. The sensitivity
6. The mode of operation
7. Access Point address
8. The bit-rate
9. The RTS threshold
10. The fragmentation threshold
11. The encryption key
12. The power management settings

[1] Bring your wireless network up (assuming interface name is wlan0):

ifconfig wlan0 up

[2] Scan for wireless access points:

iwlist wlan0 scan
iwlist wlan0 scan | less   # pipe it to less or grep to find what you need

[3] Find the one you want and put its configs in a file under /etc/network/

[4] Down the wireless interface and bring it up with you config file

ifconfig wlan0 down
ifup -i /etc/network/config_filename wlan0

Simplied (three commands to get wireless up and running; assuming interface name is wlan0):

• NOTE: iwconfig only supports open and WEP encrypted networks; no WPA/WPA2 support
• For WPA/WPA2 use the above ifupdown routine

ifconfig wlan0
iwconfig wlan0 essid NETWORK_NAME key WIRELESS_KEY
dhclient wlan0

[1] Bring your wireless network up:

ifconfig wlan0 up

[2] Scan for wireless access points:

iwlist wlan0 scan
iwlist wlan0 scan | less   # pipe it to less or grep to find what you need

From the output of the scan you should see a line (or lines) like:

 ESSID: "NETWORK_NAME"   #name of an available wireless network

[3] Connect to the network of your choice:

<code>
iwconfig wlan0 essid NETWORK_NAME                   # open network
iwconfig wlan0 essid NETWORK_NAME key open          # open network if above doesn't work
iwconfig wlan0 essid NETWORK_NAME key off           # open network if above doesn't work
iwconfig wlan0 essid NETWORK_NAME key WIRELESS_KEY  # encrypted network

NOTE: The iwconfig command defaults to HEX values for wireless keys. If you need to use ascii you have to prepend the “s” prefix to your key like so:

iwconfig wlan0 essid NETWORK_NAME key s:WIRELESS_KEY

[4] After you connect, if you need dhcp to assign an IP:

dhclient wlan0

[5] Shut it down…

ifconfig wlan0 down

Network Manager Tools (included with install):

• nmcli: the dedicated command line tool used in order to configure, add, edit and remove connections using the Network Manager;
• nmtui: (tab-complete to see shortcuts) a graphical user interface that provides just a subset of features compated to nmcli. Using nmtui, you can edit a connection, activate a connection or change the hostname of your computer;
• nm-applet: available in GNOME desktop environments, this applet is used as an interface overlay which can be used in order to connect or disconnect from networks.

Start/Stop/Restart Networking:

systemctl stop networking.service
systemctl start networking.service
systemctl restart networking.service  # same as above two, combo

If that doesn't work:

service network-manager restart

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