Netctl

zh-CN:NetctlTemplate:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary text Template:Article summary heading Template:Article summary wiki Template:Article summary end Netctl is a new Arch project that replaces netcfg. Netctl is the future (and present) of CLI-based network management on Arch Linux.

Installation

The netctl package is available in the official repositories. Installing netctl will replace netcfg.

netctl and netcfg are conflicting packages. You will be potentially connectionless after installing netctl if your profiles are misconfigured.

Required reading

It is advisable to read the following man pages before using netctl:

• netctl
• netctl.profile
• netctl.special

Configuration

netctl may be used to introspect and control the state of the systemd services for the network profile manager. Example configuration files are provided for the user to assist them in configuring their network connection. These example profiles are located in /etc/netctl/examples/. The common configurations include:

• ethernet-dhcp
• ethernet-static
• wireless-wpa
• wireless-wpa-static

For wireless settings, use wifi-menu -o will generate the config file in /etc/netctl.

To use an example profile, simply copy one of them from /etc/netctl/examples/ to /etc/netctl/ and configure it to your needs:

# cp /etc/netctl/examples/wireless-wpa /etc/netctl/profile

Once you have created your profile, make an attempt to establish a connection using the newly created profile by running:

# netctl start profile

Note: 'profile' is the file name, not including the full path. Providing the full path will make netctl return with an error code.

If issuing the above command results in a failure, then use journalctl -xn and netctl status profile in order to obtain a more in depth explanation of the failure. Make the needed corrections to the failed configuration and retest.

Automatic operation

Just one profile

If you are using only one profile, once that profile is started successfully, it can be enabled using

# netctl enable profile 

This will create and enable a systemd service that will start when the computer boots.

Note: The connection to a dhcp-server is only established if the interface is connected and up at boot time (or when the service starts). In order to have an automatic connection established on cable connect, proceed to #Multiple profiles.

Multiple profiles

Whereas with netcfg there was net-auto-wireless.service and net-auto-wired.service, netctl uses netctl-auto@interface.service for wireless profiles, and netctl-ifplugd@interface.service for wired profiles. In order to make the netctl-auto@interface.service work for wireless interfaces, the package wpa_actiond is required to be installed. In order to make the netctl-ifplugd@interface.service work for wired interfaces, the package ifplugd is required to be installed. Configure /etc/ifplugd/ifplugd.conf accordingly. Automatic selection of a WPA-enabled profile by netctl-auto is not possible with option Security=wpa-config, please use Security=wpa-configsection instead.

To set preferred wired profile for auto-connecting specify AutoWired=yes in that profile. By default on failure ifplugd will pass to other DHCP wired profiles, then to static ones. If you don't want it to do so, set ForceConnect=yes.

Once your profiles are set and verified to be working, simply enable these services with

# systemctl enable netctl-auto@interface.service 
# systemctl enable netctl-ifplugd@interface.service  

Note: If any of the profiles contain errors, such as an empty Key= variable, the unit will fail to load at boot.

If you have previously enabled a profile through netctl, run

# netctl disable profile

to prevent the profile from starting twice at boot, and possibly causing issues with wpa_supplicant.

Note:

• If there is ever a need to alter a currently enabled profile, execute netctl reenable <profile> to apply the changes.
• interface is hardware minus, e.g netctl-auto@wlan0.service or netctl-auto@enp2s0.service

Migrating from netcfg

Warning: netctl conflicts with netcfg so disable existing netcfg@profile service before installing netctl.

netctl uses /etc/netctl to store its profiles, not /etc/network.d (netcfg's profile storage location).

In order to migrate from netcfg, at least the following is needed:

• Move network profile files to the new directory.
• Rename variables therein according to netctl.profile(5) (Most variable names have only UpperCamelCase i.e CONNECTION= becomes Connection=).
• For static IP configuration make sure the Address= variables have a netmask after the IP (e.g. Address=('192.168.1.23/24' '192.168.1.87/24') in the example profile).
• If you setup a wireless profile according in the wireless-wpa-configsection example, note that this overrides wpa_supplicant options defined above the brackets. For a connection to a hidden wireless network, add scan_ssid=1 to the options in the wireless-wpa-configsection; Hidden=yes does not work there.
• Unquote interface variables and other variables that don't strictly need quoting (this is mainly a style thing).
• Run netctl enable profile for every profile in the old NETWORKS array. 'last' doesn't work this way, see netctl.special(7).
• Use netctl list/netctl start profile instead of netcfg-menu. wifi-menu remains available.
• It may be a good idea to use systemctl --type=service to ensure that no other service is running that may want to configure the network. Multiple networking services will conflict.
• Unlike netcfg, by default netctl fails to bring up a NIC when it is not connected to another powered up NIC. To solve this problem, add SkipNoCarrier=yes at the end of your /etc/netctl/profile-file.

Passphrase obfuscation (256-bit PSK)

Users not wishing to have the passphrase to their wireless network stored in plain text have the option of storing the corresponding 256-bit pre-shared key (PSK) instead, which is calculated from the passphrase and the SSID using standard algorithms.

• Method 1: Use wifi-menu -o to generate a config file in /etc/netctl
• Method 2: Manual settings as follows. If the passphrase fails, try removing the \" in Key= (see note below)

For both methods it is suggested to chmod 600 /etc/netctl/<config_file> to prevent user access to the password.

Calculate your 256-bit PSK using wpa_passphrase:

Usage: wpa_passphrase [ssid] [passphrase]

$ wpa_passphrase archlinux freenode

In a second terminal window, copy the example file wireless-wpa from /etc/netctl/examples to /etc/netctl:

# cp /etc/netctl/examples/wireless-wpa /etc/netctl/wireless-wpa

You will then need to edit /etc/netctl/wireless-wpa using your favorite text editor and add the pre-shared key, that was generated earlier using wpa_passphrase, to the Key variable of this profile.

Once completed your network profile wireless-wpa containing a 256-bit PSK should resemble:

/etc/netctl/wireless-wpa

Description='A simple WPA encrypted wireless connection using 256-bit PSK'
Interface=wlp2s2
Connection=wireless
Security=wpa
IP=dhcp
ESSID=archlinux
Key=\"64cf3ced850ecef39197bb7b7b301fc39437a6aa6c6a599d0534b16af578e04a

Note:

• Make sure to use the special non-quoted rules for Key= that are explained at the end of netctl.profile(5).
• The key that you put in the profile configuration is enough to connect to a WPA-PSK network, which means this procedure is only good to hide the human-readable passphrase but will not prevent anyone with read access to this file from connecting to the network. You should ask yourself if there is any use in this at all, since using the same passphrase for anything else is a very poor security measure.

Support

Official announcement thread: https://bbs.archlinux.org/viewtopic.php?id=157670

Tips and tricks

Replace 'netcfg current'

As of April 2013 there is no netctl alternative to netcfg current. If you relied on it for something, like a status bar for a tiling window manager, you can now use:

# netctl list | awk '/*/ {print $2}'

or, when netctl-auto was used to connect:

# wpa_cli -i interface status | sed -n 's/^id_str=//p'

Eduroam

To connect to a wireless network at university it is very likely you need a profile looking like this (tested in Freiburg, Germany):

/etc/netctl/wlan0-eduroam

Description='Eduroam-profile for <user>'
Interface=wlan0
Connection=wireless
Security=wpa-configsection
IP=dhcp
WPAConfigSection=(
 'ssid="eduroam"'
 'proto=RSN'
 'key_mgmt=WPA-EAP'
 'pairwise=CCMP'
 'auth_alg=OPEN'
 'eap=PEAP'
 'identity="<user>"'
 'password="<password>"'
)