systemd-networkd (简体中文)

start/enable 以使用 systemd-networkd。

start/enable 是可选的，它为本地应用程序提供网络名称（DNS）解析服务。是否使用它可以考虑下面几条：

• 如果 .network 文件中指定了 DNS 条目，systemd-resolved 服务是必需的
• 它能够自动地从 DHCP 客户端获取 DNS 地址
• 请搞明白 resolv.conf 和 systemd-resolved 如何互相影响，以便正确配置要使用的 DNS 服务器。更多相关信息可以参见 systemd-resolved
• 注意：即使没有启用 systemd-networkd， systemd-resolved 也能够提供服务。

在本节中，所有配置都存储为在 /etc/systemd/network/ 目录下 形如 的文件。有关选项的完整列表和处理顺序可以参考 #配置文件 和 。

Systemd/udev 会自动为所有本地以太网、WLAN 和 WWAN 接口分配可预测且稳定的网络接口名。使用 以列出系统上所有设备。

在修改了配置文件之后，restart 以使得它们生效。

能够被使用多次来指定多个 IPv4 或者 IPv6 地址。

参见 #network 文件 或者 了解更多配置项。

为了能够使用 systemd-networkd 连接一个无线网络，需要一个被其他应用，比如 wpa_supplicant 或 Iwd，配置好的无线适配器。

如果无线适配器有一个静态地址，它的配置（除了接口的名字）跟有线适配器是一样的。

This setup will enable a DHCP IP for both a wired and wireless connection making use of the metric directive to allow the kernel to decide on-the-fly which one to use. This way, no connection downtime is observed when the wired connection is unplugged.

The kernel's route metric (same as configured with ip) decides which route to use for outgoing packets, in cases when several match. This will be the case when both wireless and wired devices on the system have active connections. To break the tie, the kernel uses the metric. If one of the connections is terminated, the other automatically wins without there being a gap with nothing configured (ongoing transfers may still not deal with this nicely but that is at a different OSI layer).

/etc/systemd/network/25-wireless.network

[Match]
Name=wlp2s0

[Network]
DHCP=ipv4

[DHCP]
RouteMetric=20

作为更改设备名称的替代方案，systemd 使用.link文件用于接口重命名。常见的例子是基于 MAC 地址给一个 USB 接口以太网适配器设置一个可预见的接口名称。这类设备依其连接到不同 USB 接口而具有不同的接口名称。

这类文件用于设置网络配置变量，尤其适用于服务器和容器。

.network文件含有下列小节：、、[Network]、、以及。下列为每小节的通用配置。详情及范例请参阅。

• 由空白字符分割的网卡硬件地址列表
• 由空白字符分割的设备名列表，可以包含集合字符（如：）。使用前缀字符禁用列表中的名字。
• Host= 机器的主机名
• 检查系统是否运行于虚拟化环境。选项值表示仅应用于物理主机，选项值表示应用于任何容器或虚拟机。

• useful for MAC address spoofing
• setting a larger MTU value (e.g. when using jumbo frames) can significantly speed up your network transfers
• Multicast allow the usage of multicast on interface(s)

• 这个选项必选，除非使用了 DHCP。

• 这个选项必选，除非使用了 DHCP
• Destination= 路由的目的地前缀，可能后接一个斜线字符和前缀长度

如果选项没有出现在小节，本节将视为默认路由。

这类文件将创建虚拟网络设备。包含两个小节： 和 。下列为每小节的通用配置。详情及范例请参阅。

• Host= 主机名
• 检查是否运行于虚拟机中

最通用的配置为：

• 接口名称。必须提供
• 例如：bridge, bond, vlan, veth, sit，等等。必须提供

These files are an alternative to custom udev rules and will be applied by udev as the device appears. They have two sections: and . Below are commonly configured keys for each section. See for more information and examples.

• the MAC address
• Host= the host name
• the device type e.g. vlan

• persistent or random addresses, or
• a specific address

This setup will enable a DHCP IP for host and container. In this case, both systems will share the same IP as they share the same interfaces.

/etc/systemd/network/''MyDhcp''.network

[Match]
Name=en*

[Network]
DHCP=ipv4

Then, enable and start on your container.

You can of course replace by the full name of your ethernet device given by the output of the command.

• on host and container:

By default, hostname received from the DHCP server will be used as the transient hostname.

To change it add in section

If you did not want to configure a DNS in and want to rely on DHCP for setting it up, you need to enable and symlink to

# ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf

See systemd-resolved.service(8) for more details.

First, create a virtual bridge interface. We tell systemd to create a device named br0 that functions as an ethernet bridge.

/etc/systemd/network/''MyBridge''.netdev

[NetDev]
Name=br0
Kind=bridge

Restart to have systemd create the bridge.

On host and container:

Note that the interface br0 is listed but is still DOWN at this stage.

The next step is to add to the newly created bridge a network interface. In the example below, we add any interface that matches the name en* into the bridge br0.

The ethernet interface must not have DHCP or an IP address associated as the bridge requires an interface to bind to with no IP: modify the corresponding accordingly to remove the addressing.

Now that the bridge has been created and has been bound to an existing network interface, the IP configuration of the bridge interface must be specified. This is defined in a third .network file, the example below uses DHCP.

As we want to give a separate IP for host and container, we need to Disconnect networking of the container from the host. To do this, add this option --network-bridge=br0 to your container boot command.

# systemd-nspawn --network-bridge=br0 -bD /path_to/my_container

• 在宿主机上

• 在容器中

• we have now one IP address for on the host, and one for in the container
• two new interfaces have appeared: in the host and in the container. This comes as a result of the --network-bridge=br0 option. This option implies another option, --network-veth. This means a virtual Ethernet link has been created between host and container.
• the DHCP address on comes from the system file.
• on host

the above command output confirms we have a bridge with two interfaces binded to.

• 在宿主机上

• 在容器中

the above command outputs confirm we have activated and interfaces with an IP address and Gateway 192.168.1.254. The gateway address has been automatically grabbed by systemd-networkd

Setting a static IP for each device can be helpful in case of deployed web services (e.g FTP, http, SSH). Each device will keep the same MAC address across reboots if your system file has the MACAddressPolicy=persistent option (it has by default). Thus, you will easily route any service on your Gateway to the desired device.

The following configuration needs to be done for this setup:

• on host

The configuration is very similar to that of #DHCP 用于两个独立 IP. First, a virtual bridge interface needs to be created and the main physical interface needs to be bound to it. This task can be accomplished with the following two files, with contents equal to those available at the DHCP section.

/etc/systemd/network/MyBridge.netdev
/etc/systemd/network/MyEth.network

Next, you need to configure the IP and DNS of the newly created virtual bridge interface. The following MyBridge.network provides an example configuration:

• on container

First, we shall get rid of the system file, which provides a DHCP configuration for the default network interface of the container. To do it in a permanent way (e.g. even after upgrades), do the following on the container. This will mask the file since files of the same name in /etc/systemd/network take priority over . Keep in mind that this file can be kept if you only want a static IP on the host, and want the IP address of your containers to be assigned via DHCP.

# ln -sf /dev/null /etc/systemd/network/80-container-host0.network

Then, configure an static IP for the default network interface and enable and start on your container. An example configuration is provided below:

If running services like Samba/NFS which fail if they are started before the network is up, you may want to enable the . This is, however, rarely necessary because most networked daemons start up okay, even if the network has not been configured yet.

systemd-resolved may not search the local domain when given just the hostname, even when UseDomains=yes or is present in the appropriate .network file, and that file produces the expected in . You can run or to check if the search domains are actually being picked up.

Possible workarounds:

• Disable LLMNR to let systemd-resolved immediately continue with appending the DNS suffixes
• Trim 's database (e.g., by removing option after resolve service)
• Switch to using fully-qualified domain names
• Use /etc/hosts to resolve hostnames
• Fall back to using glibc's instead of using systemd's resolve

First PC have two LAN. Second PC have one LAN and connected to first PC. Lets go second PC to give all access to LAN after bridged interface:

# sysctl net.bridge.bridge-nf-filter-pppoe-tagged=0
# sysctl net.bridge.bridge-nf-filter-vlan-tagged=0
# sysctl net.bridge.bridge-nf-call-ip6tables=0
# sysctl net.bridge.bridge-nf-call-iptables=0
# sysctl net.bridge.bridge-nf-call-arptables=0