# Connman

Related articles

- Network configuration
- Wireless network configuration
- Category:Network configuration

ConnMan is a command-line network manager designed for use with embedded devices and fast resolve times. It is modular through a plugin architecture, but has native dhcp and ntp support.

## Installation

Install the connman package. wpa_supplicant and bluez are optional dependencies required for Wi-Fi and Bluetooth functionality respectively.

Before enabling `connman.service`, ensure any existing network configuration is disabled.

### Desktop clients

- cmst — Qt GUI for ConnMan.

  https://github.com/andrew-bibb/cmst || cmstAUR

- connman-ncurses — Simple ncurses UI for ConnMan; not all of connman functionality is implemented, but usable (with X or from terminal without X), see the wiki.

  https://github.com/eurogiciel-oss/connman-json-client || connman-ncurses-gitAUR

- connman-notify — Connman event notification client

  https://github.com/wavexx/connman-notify || connman-notifyAUR[broken link: archived in aur-mirror]

- ConnMan-UI — GTK3 client applet.

  https://github.com/tbursztyka/connman-ui || connman-ui-gitAUR

- connman_dmenu — Client/frontend for dmenu.

  https://github.com/taylorchu/connman_dmenu || connman_dmenu-gitAUR

- Econnman — Enlightenment desktop panel applet.

  http://www.enlightenment.org || econnmanAUR

- LXQt-Connman-Applet — LXQt desktop panel applet.

  https://github.com/surlykke/lxqt-connman-applet || lxqt-connman-applet-gitAUR

- qconnman-ui — Qt management interface used on O.S. Systems products

  https://github.com/OSSystems/qconnman-ui || qconnman-ui-gitAUR[broken link: archived in aur-mirror]

- connman-gtk — GTK client.

  https://github.com/jgke/connman-gtk || connman-gtkAUR

- gnome-extension-connman — Gnome3 extension for connman; it contains only some of the functionality without installing connman-gtk.

  https://github.com/jgke/gnome-extension-connman || https://extensions.gnome.org/extension/981/connman-extension/

## Usage

This article or section needs expansion.

Reason: Only Wired and Wi-Fi plugins are described. (Discuss in Talk:Connman#)

ConnMan has a standard command line client `connmanctl`. It can run in 2 modes:

- In command mode commands are entered as arguments to `connmanctl` command, just like systemctl.
- Interactive mode is started by typing `connmanctl` without arguments. Prompt will change to `connmanctl>` to indicate it is waiting for user commands, just like python interactive mode. The interactive mode supports tab completion, which makes finding the correct connection easy.

### Wired

ConnMan will automatically handle wired connections.

### Wi-Fi

#### Enabling and disabling wifi

To check if wifi is enabled you can run `connmanctl technologies` and check for the line that says `Powered: True/False`. To power the wifi on you can run `connmanctl enable wifi` or if you need to disable it you can run `connmanctl disable wifi`. Other ways to enable wifi could include using the `Fn` keys on the laptop to turn it on or running `ip link set <interface> up`.

#### Connecting to an open access point

The commands in this section show how to run `connmanctl` in command mode.

To scan the network `connmanctl` accepts simple names called technologies. To scan for nearby Wi-Fi networks:

    $ connmanctl scan wifi

To list the available networks found after a scan run (example output):

    $ connmanctl services

    *AO MyNetwork               wifi_dc85de828967_68756773616d_managed_psk
        OtherNET                wifi_dc85de828967_38303944616e69656c73_managed_psk
        AnotherOne              wifi_dc85de828967_3257495245363836_managed_wep
        FourthNetwork           wifi_dc85de828967_4d7572706879_managed_wep
        AnOpenNetwork           wifi_dc85de828967_4d6568657272696e_managed_none

To connect to an open network, use the second field beginning with `wifi_`:

    $ connmanctl connect wifi_dc85de828967_4d6568657272696e_managed_none

Tip: Network names can be tab-completed.

You should now be connected to the network. Check using `ip addr` or `connmanctl state`.

#### Connecting to a protected access point

For protected access points you will need to provide some information to the ConnMan daemon, at the very least a password or a passphrase.

The commands in this section show how to run `connmanctl` in interactive mode, it is required for running the `agent` command. To start interactive mode simply type:

    $ connmanctl

You then proceed almost as above, first scan for any Wi-Fi technologies:

    connmanctl> scan wifi

To list services:

    connmanctl> services

Now you need to register the agent to handle user requests. The command is:

    connmanctl> agent on

You now need to connect to one of the protected services. To do this easily, just use tab completion for the wifi_ service. If you were connecting to OtherNET in the example above you would type:

    connmanctl> connect wifi_dc85de828967_38303944616e69656c73_managed_psk

The agent will then ask you to provide any information the daemon needs to complete the connection. The information requested will vary depending on the type of network you are connecting to. The agent will also print additional data about the information it needs as shown in the example below.

    Agent RequestInput wifi_dc85de828967_38303944616e69656c73_managed_psk
      Passphrase = [ Type=psk, Requirement=mandatory ]
      Passphrase?

Provide the information requested, in this example the passphrase, and then type:

    connmanctl> quit

If the information you provided is correct you should now be connected to the protected access point.

### Settings

Settings and profiles are automatically created for networks the user connects to often. They contain fields for the passphrase, essid and other information. Profile settings are stored in directories under `/var/lib/connman/` by their service name. To view all network profiles run this command from root shell:

    # cat /var/lib/connman/*/settings

Note: VPN settings can be found in `/var/lib/connman-vpn/`.

### Technologies

Various hardware interfaces are referred to as Technologies by ConnMan.

To list available technologies run:

    $ connmanctl technologies

To get just the types by their name one can use this one liner:

    $ connmanctl technologies | awk '/Type/ { print $NF }'

Note: The field `Type = tech_name` provides the technology type used with `connmanctl` commands

To interact with them one must refer to the technology by type. Technologies can be toggled on/off with:

    $ connmanctl enable technology_type

and:

    $ connmanctl disable technology_type

For example to toggle off wifi:

    $ connmanctl disable wifi

Warning: connman grabs rfkill events. It is most likely impossible to use `rfkill` or `bluetoothctl` to (un)block devices, yet hardware keys may still work.[1] Always use `connmanctl enable|disable`

## Tips and tricks

### Avoid changing the hostname

By default, ConnMan changes the transient hostname on a per network basis. This can create problems with X authority: If ConnMan changes your hostname to something else than the one used to generate the xauth magic cookie, then it will become impossible to create new windows. Symptoms are error messages like "No protocol specified" and "Can't open display: :0.0". Manually resetting the host name fixes this, but a permanent solution is to prevent ConnMan from changing your host name in the first place. This can be accomplished by adding the following to `/etc/connman/main.conf`:

    [General]
    AllowHostnameUpdates=false

Make sure to restart the `connman.service` after changing this file.

For testing purposes it is recommended to watch the journal and plug the network cable a few times to see the action.

### Prefer ethernet to wireless

By default ConnMan does not prefer ethernet over wireless, which can lead to it deciding to stick with a slow wireless network even when ethernet is available. You can tell connman to prefer ethernet adding the following to `/etc/connman/main.conf`:

    [General]
    PreferredTechnologies=ethernet,wifi

### Exclusive connection

ConnMan allows you to be connected to both ethernet and wireless at the same time. This can be useful as it allows programs that established a connection over wifi to stay connected even after you connect to ethernet. But some people prefer to have only a single unambiguous connection active at a time. That behavior can be activated by adding the following to `/etc/connman/main.conf`:

    [General]
    SingleConnectedTechnology=true

### Connecting to eduroam

See WPA2 Enterprise#connman.

### Avoiding conflicts with local DNS server

If you are running a local DNS server, it will likely have problems binding to port 53 (TCP and/or UDP) after installing Connman. This is because Connman includes its own DNS proxy which also tries to bind to those ports. If you see log messages from BIND or dnsmasq like

    "named[529]: could not listen on UDP socket: address in use"

this could be the problem. To verify which application is listening on the ports, you can execute `ss -tulpn` as root.

To fix this connmand can be started with the options `-r` or `--nodnsproxy` by overriding the systemd service file. Create the folder `/etc/systemd/system/connman.service.d/` and add the file `disable_dns_proxy.conf`:

    [Service]
    ExecStart=
    ExecStart=/usr/bin/connmand -n --nodnsproxy

Make sure to reload the systemd daemon and restart the `connman.service`, and your DNS proxy, after adding this file.

### Blacklist interfaces

If something like Docker is creating virtual interfaces Connman may attempt to connect to one of these instead of your physical adapter if the connection drops. A simple way of avoiding this is to blacklist the interfaces you do not want to use. Connman will by default blacklist interfaces starting with `vmnet`, `vboxnet`, `virbr` and `ifb`, so those need to be included in the new blacklist as well.

Blacklisting interface names is also useful to avoid a race condition where connman may access `eth#` or `wlan#` before systemd/udev can change it to use a predictable interface name like `enp4s0`. Blacklisting the conventional (and unpredictable) interface prefixes makes connman wait until they are renamed.

If it does not already exist, create `/etc/connman/main.conf`:

    [General]
    NetworkInterfaceBlacklist=vmnet,vboxnet,virbr,ifb,docker,veth,eth,wlan

Once `connman.service` has been restarted this will also hide all the `veth#######` interfaces from GUI tools like Econnman.

## Troubleshooting

### Error /net/connman/technology/wifi: Not supported

You need to install wpa_supplicant and then restart connman service: `systemctl restart connman.service`.

## See also

- git repo documentation - for further detailed documentation

Category:

- Network configuration

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