dotfiles/notes/linux/linux_networks.md

Networks

This file covers wifi and bluetooth connections on linux

Required packages for the guide:

• systemd
• NetworkManager
• bluetoothctl

Optional GUI tools to make this easier:

• pacman -S nm-connection-editor
• pacman -S blueberry

Basic networks

For Archlinux, choose between NetworkManager and netctl for your networking needs. NetworkManager comes from the GNOME project and is fully feature packed from the getgo. Netctl is a set of light shell scripts that rely on external packages for networking, so a bit harder to install

Both can be checked with systemd

systemctl status netctl.service
systemctl status NetworkManager.service

Make sure only one is running and enabled. Using both at the same time will result in system slowdowns, especially at boot times

NetworkManager and netctl conflict

If your system is running some /sys/.../subnet... for 90s at startup, likely netctl is trying to start up a device, though the device name has changed. Places to check:

/etc/NetworkManager/system-connections/
cd /etc/systemd/system/multi-user.target.wants/ && rg enp0s3
vi /etc/systemd/system/multi-user.target.wants/netctl@enp4s0.service
vi netctl@enp4s0.service

If you are using both by accident, make sure to use the native disable in addition to the systemd disable. For example, with netctl:

systemctl disable netctl
systemctl disable netctl@enp4s0.service
netctl disable enp4s0

Public networks

Public networks often use a captive portal to make users accept their terms and conditions

1. Connect to the network using nmtui or similar
2. Use a GUI browser and navigate to any site
3. If that doesn't work, try navigating to a non-https using page
4. If that doesn't work, try navigating to a site you've never visited in incognito
5. If that doesn't work, try navigating to the router at 192.168.[0-1].[0-1]

Bluetooth

Before starting bluetooth, make sure bluetooth.service is running, otherwise nothing will work

systemctl start bluetooth.service

You may optionally install the blueberry GUI package. It's quite light and limited, though it's a good way to check if your devices are connected

Keyboard

Start bluetoothctl. The command sequence to connect will look something like:

$ bluetoothctl
[bluetooth]# power on
[bluetooth]# agent off
[bluetooth]# agent KeyboardOnly
[bluetooth]# scan on
[bluetooth]# pair <MAC-ADDR>
[bluetooth]# trust <MAC-ADDR>
[bluetooth]# connect <MAC-ADDR>
[bluetooth]# quit

When you turn scan on, the list may explode with various mac addresses. Try to find your keyboard amongst those. During the pair section, bluetoothctl may prompt you with 6 digits. Type those on the keyboard and possibly hit enter after them

See the Archwiki page for more info

Bluetooth headphones

This section connected AirPods Pro. Setup may differ for other devices

Start by connecting your headphones with a very similar set of steps as the keyboard guide above. Use default-agent instead of agent KeyboardOnly. For example:

$ bluetoothctl
[bt]# power on
[bt]# default-agent
[bt]# scan on
  [NEW] Device 00:8A:76:4D:9B:BB Anna’s Airpods
[bt]# trust 00:8A:76:4D:9B:BB
[bt]# pair 00:8A:76:4D:9B:BB
[bt]# connect 00:8A:76:4D:9B:BB

Once connected, blue headphones may cutout or just not play back anything. This is a PulseAudio issue. The bluetooth sound latency may need to be adjusted

Start by finding your bluetooth card's name with

$ pactl list | grep -Pzo '.*bluez_card(.*\n)*'

Next increase the audio latency. 50000ms seems to work well for AirPods Pro, though this is likely different for other headphones

$ pactl set-port-latency-offset bluez_card.00_8A_76_4D_9B_BB headphone-output 50000
$ systemctl restart bluetooth.service

Repeat the steps above, adjusting the bluetooth sound latency, until it works. Consider using the blueberry GUI to quickly reconnect the headphones on each bluetooth.service restart. Don't forget to relaunch blueberry every time too

kill $(pgrep ^blueberry$) && systemctl restart bluetooth.service && blueberry &

Enterprise networks

Large organizations, like universities, use enterprise security on their networks. These require an account to login, not just a password

The guide below assumes the network's name is "UWS" and your login username is "emiliko"

You can install the optional nm-connection-editor to make things easier

$ nmcli device wifi list

This should show the network you're looking for

If your network is not using PAP authentication, it may be possible to just connect with a simple password, try:

nmcli --ask device wifi connect UWS

Otherwise run this line, replacing the necessary information in the line above. Particularly UWS, emiliko and wlan0. For wlan0, find your wifi device with ip link. enp... is usually ethernet

nmcli connection add type wifi con-name "UWS" ifname wlan0 ssid "UWS" -- wifi-sec.key-mgmt wpa-eap 802-1x.eap ttls 802-1x.phase2-auth mschapv2 802-1x.identity "emiliko"

Option 1: With nm-connection-editor

Open nm-connection-editor. Go into "Wifi-Security" and make it look like:

WPA & WPA2 Enterprise
Tunnled TLS
CA Certificate: (None)
Check No CA certificate required
Inner authentication: PAP

Type in your login credentials at the bottom. Now run

Option 2: Without nm-connection-editor

If you don't have the GUI tool nm-connection-editor and no way to install it, you can try editing the network's profile directly. The relevant file is at /etc/NetworkManager/system-connections/UWS.nmconnection

This file should look something like below, with relevant information replaced. The file can only be accessed by root

[connection]
id=UWS
uuid=cb62f680-e1da-41c9-bfa0-35e7ef6f5137
type=wifi
interface-name=wlan0
timestamp=1657043376

[wifi]
mode=infrastructure
ssid=UWS

[wifi-security]
key-mgmt=wpa-eap

[802-1x]
eap=ttls;
identity=emiliko
password=PutYourPasswordInPlainTextHere_YesPlainText
phase2-auth=pap

[ipv4]
method=auto

[ipv6]
addr-gen-mode=stable-privacy
method=auto

[proxy]

Alternatively, use the file above as a reference to edit it via

nmcli connection edit UWS

After setting up above

nmcli device wifi connect UWS

NetworkManager takes a bit, about 30s, to finish authentication. This will also happen during boot, so you can't use the network right away

If your network does not use PAP authetication, it might just work to type the password in

nmcli --ask device wifi connect UWS