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Systemd/networkd: Difference between revisions

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{{Systemd/breadcrumb}}
{{DISPLAYTITLE:systemd-networkd}}
{{DISPLAYTITLE:systemd-networkd}}
[https://www.freedesktop.org/software/systemd/man/systemd-networkd.html systemd-networkd] is the network[[Category: Networking]] configuration component of the [[systemd]][[Category:systemd]] software suite. It is well integrated into NixOS below {{Nixos:option|systemd.network}} and should be preferred over {{Nixos:option|networking.interfaces}} options for most use cases, since it receives far superior maintenance.
[https://www.freedesktop.org/software/systemd/man/systemd-networkd.html systemd-networkd] is the network configuration component of the [[systemd]][[Category:systemd]] software suite. It is well integrated into NixOS below {{Nixos:option|systemd.network}} and should be preferred over {{Nixos:option|networking.interfaces}} options for most use cases, since it receives far superior maintenance.


Configuration for networkd is split into three sections.
Configuration for networkd is split into three sections.
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These use cases are better served by [[NetworkManager]] and its various frontends, that provides a better integrated user experience for various desktop systems.
These use cases are better served by [[NetworkManager]] and its various frontends, that provides a better integrated user experience for various desktop systems.


{{Note|Both systemd-networkd and NetworkManager can exist in parallel on the same machine,
{{Note|Both systemd-networkd and NetworkManager can exist in parallel on the same machine, when they manage a distinct set of interfaces. If upstream connectivity is managed by NetworkManager (for example, NM handles wifi and networkd does VM networking), set {{Nixos:option|systemd.network.wait-online.enable}} to false so that boot isn't blocked on connectivity that networkd will never provide.}}
when they manage a distinct set of interfaces.}}


=== Enabling ===
=== Enabling ===
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</nowiki>}}
</nowiki>}}


Note that we usually prefix the configuration file with a number. This can be important, because networkd collects all available configuration files, then sorts them alphabetically, and uses the first match for each interface as its configuration. This happens separately for <code>.link</code>, <code>.netdev</code> and <code>.network</code> files, so that you can have one configuration of each type per interface.
Note that we usually prefix the configuration file with a number. This can be important, because networkd collects all available configuration files, then sorts them alphanumerically, and uses the first match for each interface as its configuration. This happens separately for <code>.link</code>, <code>.netdev</code> and <code>.network</code> files, so that you can have one configuration of each type per interface.


=== Debugging ===
=== Debugging ===
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<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
systemd.services."systemd-networkd".environment.SYSTEMD_LOG_LEVEL = "debug";
systemd.services."systemd-networkd".environment.SYSTEMD_LOG_LEVEL = "debug";
</syntaxhighlight>Log level can also be changed at runtime with<syntaxhighlight lang="bash">
$ systemctl service-log-level systemd-networkd.service debug
# or
$ systemctl service-log-level systemd-networkd.service info
</syntaxhighlight>
</syntaxhighlight>


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** Does not modify properties (e.g., MTU, VLAN ID, VXLAN ID, Wireguard Peers) of existing netdevs
** Does not modify properties (e.g., MTU, VLAN ID, VXLAN ID, Wireguard Peers) of existing netdevs
*** https://github.com/systemd/systemd/issues/9627
*** https://github.com/systemd/systemd/issues/9627
*** This should be fixed as of systemd v257 (https://github.com/systemd/systemd/pull/34909)


=== network-online.target ===
=== network-online.target ===
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<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
systemd.network."50-enp3s0" = {
systemd.network.networks."50-enp3s0" = {
   matchConfig.Name = "enp3s0";
   matchConfig.Name = "enp3s0";
   # acquire a DHCP lease on link up
   # acquire a DHCP lease on link up
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Examples should be concise and give proper hints on how to achieve a reliably working <code>network-online.target</code>.
Examples should be concise and give proper hints on how to achieve a reliably working <code>network-online.target</code>.
=== Interface Naming ===
The name of an interface can be changed based on different matches. This is useful for pretty names (e.g. wan, lan), but also if you want to make sure that your interface name never changes. This might be useful because even with predictable interface naming your interface name can change, for example when you add a new PCIe card and indexing changes, or due to kernel changes the way your mainboard gets interpreted changes.<syntaxhighlight lang="nix">
  systemd.network.links."10-wan" = {
    # Check systemd.link(5) for other matchers
    matchConfig.Path = "pci-0000:09:00.0";
    linkConfig.Name = "wan";
  };
</syntaxhighlight>


=== DHCP/RA ===
=== DHCP/RA ===
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     matchConfig.Name = "enp1s0";
     matchConfig.Name = "enp1s0";
     address = [
     address = [
        # configure addresses including subnet mask
      # configure addresses including subnet mask
        "192.0.2.100/24"
      "192.0.2.100/24"
        "2001:DB8::2/64"
      "2001:DB8::2/64"
     ];
     ];
     routes = [
     routes = [
       # create default routes for both IPv6 and IPv4
       # create default routes for both IPv6 and IPv4
       { routeConfig.Gateway = "fe80::1"; }
       { Gateway = "fe80::1"; }
       { routeConfig.Gateway = "192.0.2.1"; }
       { Gateway = "192.0.2.1"; }
       # or when the gateway is not on the same network
       # or when the gateway is not on the same network
       { routeConfig = {
       {
         Gateway = "172.31.1.1";
         Gateway = "172.31.1.1";
         GatewayOnLink = true;
         GatewayOnLink = true;
       }; }
       }
     ];
     ];
     # make the routes on this interface a dependency for network-online.target
     # make the routes on this interface a dependency for network-online.target
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           "vlan20"
           "vlan20"
         ];
         ];
        networkConfig.LinkLocalAddressing = "no";
        linkConfig.RequiredForOnline = "carrier";
       };
       };
       "40-vlan10" = {
       "40-vlan10" = {
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       # Configure the bridge for its desired function
       # Configure the bridge for its desired function
       "40-br0" = {
       "40-br0" = {
         matchConfig.Name ="br0";
         matchConfig.Name = "br0";
         bridgeConfig = {};
         bridgeConfig = {};
        # Disable address autoconfig when no IP configuration is required
        #networkConfig.LinkLocalAddressing = "no";
         linkConfig = {
         linkConfig = {
           # or "routable" with IP addresses configured
           # or "routable" with IP addresses configured
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=== Bonding ===
=== Bonding ===


Given two hardlinks <code>enp2s0</code> and <code>enp3s0</code> create a virtual <code>bond0</code> interface using Dynamic LACP (802.3ad), hashing outgoing packets using a packet's Layer3/4 (OSI Layer) information.
<div style="margin-left: 2em; margin-bottom:1em">
''More details: [[Networking#Link aggregation]]''</div>
 
Given two hardlinks <code>enp2s0</code> and <code>enp3s0</code> create a virtual <code>bond0</code> interface using Dynamic LACP (802.3ad), hashing outgoing packets using a packet's layer 3/4 (network/transport layer in the OSI model) information.


<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
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       "30-lan" = {
       "30-lan" = {
         matchConfig.Name = "lan";
         matchConfig.Name = "lan";
         address = [
         address = [ "2001:db8:1122:3344::1/64" ];
          "2001:db8:1122:3344::1/64"
        ];
         networkConfig = {
         networkConfig = {
           IPv6SendRA = true;
           IPv6SendRA = true;
         };
         };
         ipv6Prefixes = [ {
         ipv6Prefixes = [
          # Announce a static prefix
          {
          ipv6PrefixConfig.Prefix = "2001:db8:1122:3344::/64";
            # Announce a static prefix
         } ];
            ipv6PrefixConfig.Prefix = "2001:db8:1122:3344::/64";
          }
         ];
         ipv6SendRAConfig = {
         ipv6SendRAConfig = {
           # Provide a DNS resolver
           # Provide a DNS resolver
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         };
         };
       };
       };
    };
   };
   };
</syntaxhighlight>
</syntaxhighlight>
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* [https://gist.github.com/mweinelt/b78f7046145dbaeab4e42bf55663ef44 NixOS 22.11 VDSL Router (VLANs on top of Bonding, IPv6 Prefix-Delegation, pppd Integration)] by [https://github.com/mweinelt mweinelt]
* [https://gist.github.com/mweinelt/b78f7046145dbaeab4e42bf55663ef44 NixOS 22.11 VDSL Router (VLANs on top of Bonding, IPv6 Prefix-Delegation, pppd Integration)] by [https://github.com/mweinelt mweinelt]
* [https://github.com/philipwilk/nixos/blob/4fec9d73bfa7b1ecb490186522de38d25ee81e69/homelab/router/systemd.nix NixOS Unstable (25.04) Router (ipv4/ipv6 dual stack, dnssec+dnsovertls, NTP-rs)] by [https://github.com/philipwilk philipwilk]
[[Category:systemd]]
[[Category:Networking]]
Retrieved from "https://wiki.nixos.org/wiki/Systemd/networkd"