195 lines
6.3 KiB
Markdown
195 lines
6.3 KiB
Markdown
---
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title: "GNU/Linux wireless networking like it's 2020"
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subtitle: "How to add some systemd stuff inside your network configuration"
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date: 2020-07-14
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draft: false
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author: Wilfried
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tags: [ops, systemd, network, wireless]
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---
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# From netcl to iwd 📡
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ArchLinux is installed on my laptop (an XPS 15) since I got it from my job in
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2017[^1]. 3 years ago, the cli tool distributed within the distribution was
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`netctl`. It's an in-house [ArchLinux
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project](https://git.archlinux.org/netctl.git/) allowing users to manage
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networking. Overall, the tool does everything I need to get a
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network connection up and running the way I need it. One of the main thing I
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dislike about it is `wifi-menu`, a poorly design UI to search for wireless
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access points.
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Not so long ago a new challenger appeared : `iwd`. **iNet Wireless Daemon**
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(iwd) is new wireless daemon for GNU/Linux (a standard tool, available on all
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distros is better for this kind of tasks). Even if this project aims to
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replace `wpa_supplicant` it can also replace `netctl`. If you think it's a
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toy project from some random guy over the internet, bad news for you, that guy
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is : Intel™. The fact that this program acts as a daemon means one standing
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point : multiple clients will be available in the future and some well known
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managers like `network-manager` might also use it. A default one comes with
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the package as an interactive shell called `iwctl`, bye-bye `wifi-menu` !
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To begin with `iwd` enable and start the service
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```sh
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systemctl enable --now iwd.service
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```
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and open the interactive shell
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```sh
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iwctl
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```
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then list all networks
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```sh
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[iwd] station wlan0 get-networks
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Available networks
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--------------------------------------------------------------------------------
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Network name Security Signal
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--------------------------------------------------------------------------------
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ORTHANC psk ****
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MINAS ITHIL psk ****
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MINAS TIRITH psk ****
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```
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```sh
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[iwd] station wlan0 connect ORTHANC
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```
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Enter the password if needed, it will be saved for later use (in
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`/var/lib/iwd`) and check if everything is ok :
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```sh
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[iwd] station wlan0 show
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Station: wlan0
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--------------------------------------------------------------------------------
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Settable Property Value
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--------------------------------------------------------------------------------
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Scanning no
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State connected
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Connected network ORTHANC
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```
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On reboot, `iwd` will try to reconnect to last used connection.
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# Adding some salty systemd stuff 🧂
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Connected, sure, but what about an IP address 🤡 ? The first option is
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obviously `dhcpd` but it scales poorly if you have to type it everytime you
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connect to a network. Since version 0.19 `iwd` comes with a built-in DHCP
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client to enable it just add
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```txt
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[General]
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EnableNetworkConfiguration=true
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```
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in `/etc/iwd/main.conf`.
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For some people it's good enough, but you know me, I like systemd a lot and
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i'm already using `systemd-networkd`[^2] to create various kind of static network
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interfaces and network connections.
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To let `systemd-networkd` get DHCP configuration for you, ensure `systemd-networkd` is enabled
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```sh
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systemctl enable --now systemd-networkd.service
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```
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Now, add a `.network` file (in `/etc/systemd/network`) for the main wifi interface
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```txt
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[Match]
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Name=wlan0
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[Network]
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DHCP=yes
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```
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The _match_ section is used to identify the interface by name, the _network_
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one ensures that this configuration comes from DHCP.
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Now that everything is setup, systemd-networkd will get configuration for this
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interface when requested by changes on wifi interface from `iwctl`.
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# More salt with systemd-resolved 👺
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In order to piss off the ones who hate systemd, I decided to add
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`systemd-resolved` into the mix.
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`systemd-resolved` is a systemd subservice providing a local DNS system with
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caching, DNSSEC or the cool new kid : [DNS over
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TLS](https://en.wikipedia.org/wiki/DNS_over_TLS).
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As usual to enable it :
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```sh
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systemctl enable --now systemd-resolved.service
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```
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The common way to change the DNS configuration is the good old
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`/etc/resolv.conf` file. With `systemd-resolved` the recommended and most
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disruptive way is to symlink the generated stub file
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`/run/systemd/resolve/stub-resolv.conf` to `/etc/resolv.conf`.
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```txt
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# This file is managed by man:systemd-resolved(8). Do not edit.
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#
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# This is a dynamic resolv.conf file for connecting local clients to the
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# internal DNS stub resolver of systemd-resolved. This file lists all
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# configured search domains.
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#
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# Run "resolvectl status" to see details about the uplink DNS servers
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# currently in use.
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#
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# Third party programs should typically not access this file directly, but only
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# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
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# different way, replace this symlink by a static file or a different symlink.
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#
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# See man:systemd-resolved.service(8) for details about the supported modes of
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# operation for /etc/resolv.conf.
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nameserver 127.0.0.53
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options edns0
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search example.lan example.com
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```
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The stub file contains only the local DNS stub server from `systemd-resolved` (available on 127.0.0.53).
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The main purpose of this server is a caching implementation avoiding useless
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DNS requests.
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To get an idea of the number of requests where the cache is used, just check statistics
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```sh
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resolvectl statistics
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DNSSEC supported by current servers: no
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Transactions
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Current Transactions: 0
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Total Transactions: 8544
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Cache
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Current Cache Size: 65
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Cache Hits: 2394
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Cache Misses: 3939
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```
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To customize `systemd-resolved` configuration, just look at
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systemd-revolved(8) and the config file in `/etc/systemd/resolved.conf`
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(`resolvctl` with no argument can be used to get information about the
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current configuration).
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This is, in my opinion, the best networking config I ever have.
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Happy systemding !
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# Ressources
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- https://wiki.archlinux.org/index.php/Iwd
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- https://wiki.archlinux.org/index.php/Systemd-networkd
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- https://wiki.archlinux.org/index.php/Systemd-resolved
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[^1]: And it runs on [btrfs](https://en.wikipedia.org/wiki/Btrfs) with absolutely no troubles for more than 3 years
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[^2]: A systemd subservice handling networking stuff
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