Posts tagged iproute2

linux wifi cli handling

posted on 2016-06-04 14:56

Here's a walktrough on using a linux computer with a wifi card to access wlans via the cli tools. This guide is debian specific and assumes you use one of the WPA protocols for encrypting your wifi.

available tools

  • ip
  • iw
  • iwlist
  • iwconfig
  • dhclient
  • wpa_supplicant
  • wpa_passphrase
  • /etc/network/interfaces
  • wicd

You can use all of these, but it just happens you do not really need them all.

discern wlan IF

iw dev:

    Interface wlan0
    ifindex 2
    wdev 0x1
    addr 00:22:66:88:00:22
    type managed

wlan0 is my wifi interface and will be uses as an example here from now on.

enable IF (if needed)

ip l s dev wlan0 up

find networks

iw dev wlan0 scan | grep -i -e ssid -e signal


    signal: -79.00 dBm
SSID: ng-2.4G
signal: -85.00 dBm
SSID: ng-5G

So you know the available networks as well as the signal quality.

An alternative would be: iwlist wlan0 scan | grep -i -e ssid -e signal:

    Quality=26/70  Signal level=-84 dBm  
    Quality=36/70  Signal level=-74 dBm  

I will choose ng-2.4g for the next examples.

set up WPA and run daemon

# i just do not like these storing under /etc
mkdir /root/.wpa
# you are promted for the passphrase
# tee is used to show the output written to the file also directly at the shell
wpa_passphrase ng-2.4g | tee -a ~/.wpa/wpa_supplicant.conf  
## hide contents from others since the original pass is included as comment
chmod 600 ~/.wpa/wpa_supplicant.conf
# run daemon in the backgroud, automtically brings IF up
wpa_supplicant -B -i wlan0 -c ~/.wpa/wpa_supplicant.conf

So now your wpa_supplicant.conf should contain something like this:

root@zen:/home/sjas/blog# wpa_passphrase ng-2.4G MY_PASSWORD

This is likely not everything you need to connect. So either discern everything else that is missing parameter-wise by hand, or use wicd if you have a desktop environment installed.

Once you connected to the wifi of your choice, do ps aux | grep wpa_supplicant and see how it was started, and which config references via -c. Copy its contents over to your wpa_supplicant.conf.

set up interface in /etc/network/interfaces for automatic connecting

manual wlan0
iface wlan0 inet dhcp
    pre-up wpa_supplicant -B -D wext -i wlan0 -c /etc/wpa_supplicant.conf
    post-down killall -q wpa_supplicant


# enable
ifup wlan0

ifdown wlan0

how about several wlan configurations?

This is what I might use in my case:


manual wlan0
iface home2 inet dhcp
    pre-up wpa_supplicant -B -D wext -i wlan0 -c /var/lib/wicd/configurations/c404150241b4
    post-down killall -q wpa_supplicant
iface home5 inet dhcp
    pre-up wpa_supplicant -B -D wext -i wlan0 -c /var/lib/wicd/configurations/c404150241b3
    post-down killall -q wpa_supplicant

These have to be used a little differently, i.e.:

## acitivate one network:
ifup wlan0=home2
## and deactivate
ifdown wlan0

## or activate the other one:
ifup wlan0=home5
## and deactivate
ifdown wlan0

This may seem quite a bit unwieldy, but I am just fed up with network-manager or its relative, wicd, by now.

ip commands in linux

posted on 2014-06-23 17:28:11

The currently usually used tools and which ones will succeed these:

Purpose                        | Legacy net-tools | iproute2
Address and link configuration | ifconfig         | ip addr, ip link
Routing tables                 | route            | ip route
Neighbors                      | arp              | ip neigh
VLAN                           | vconfig          | ip link
Tunnels                        | iptunnel         | ip tunnel
Multicast                      | ipmaddr          | ip maddr
Statistics                     | netstat          | ss

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