Systemd/networkd: Difference between revisions

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[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.

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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.

{{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 ===

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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>

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** Does not modify properties (e.g., MTU, VLAN ID, VXLAN ID, Wireguard Peers) of existing netdevs

*** 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 ===

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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 ===

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routes = [

# 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

{

~~routeConfig = {~~

Gateway = "172.31.1.1";

GatewayOnLink = true;

};

}

];

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=== Bonding ===

''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.

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"30-lan" = {

matchConfig.Name = "lan";

address = [

address = [ "2001:db8:1122:3344::1/64" ];

"2001:db8:1122:3344::1/64"

];

networkConfig = {

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 = {

# Provide a DNS resolver

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};

</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://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]]

@@ Line 1: / Line 1: @@
 {{Systemd/breadcrumb}}
 {{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.
@@ Line 29: / Line 29: @@
 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 ===
@@ Line 79: / Line 78: @@
 <syntaxhighlight lang="nix">
 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>
@@ Line 90: / Line 93: @@
 ** Does not modify properties (e.g., MTU, VLAN ID, VXLAN ID, Wireguard Peers) of existing netdevs
 *** 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 ===
@@ Line 148: / Line 152: @@
 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 ===
@@ Line 184: / Line 197: @@
      routes = [
        # 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
        {
-         routeConfig = {
+         Gateway = "172.31.1.1";
-          Gateway = "172.31.1.1";
+        GatewayOnLink = true;
-          GatewayOnLink = true;
-        };
        }
      ];
@@ Line 295: / Line 306: @@
 === Bonding ===
+<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.
@@ Line 346: / Line 360: @@
        "30-lan" = {
          matchConfig.Name = "lan";
-         address = [
+         address = [ "2001:db8:1122:3344::1/64" ];
-          "2001:db8:1122:3344::1/64"
-        ];
          networkConfig = {
            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 = {
            # Provide a DNS resolver
@@ Line 362: / Line 376: @@
          };
        };
+    };
    };
 </syntaxhighlight>
@@ Line 379: / Line 394: @@
 * [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]]