️ systemd-networkd — Network Configuration

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tags:

• network
• sysadmin

• linux

  systemd-networkd — systemd Network Manager

systemd-networkd is systemd's native network configuration manager. It's ideal for servers and minimal systems where GUI tools are unnecessary. Configuration is done through .network and .netdev files.

Installation & Configuration

Enable systemd-networkd

sudo systemctl enable --now systemd-networkd  # Enable and start / Включить и запустить
sudo systemctl enable --now systemd-resolved  # Enable DNS resolution / Включить DNS
sudo systemctl status systemd-networkd        # Check status / Проверить статус

Configuration Paths

• System configs: /etc/systemd/network/
• Network device files: /etc/systemd/network/*.netdev
• Network config files: /etc/systemd/network/*.network
• Runtime configs: /run/systemd/network/ (volatile)

Log Locations

journalctl -u systemd-networkd -f  # Follow networkd logs / Смотреть логи

Core Management

Status Commands

networkctl status                   # Overall network status / Общий статус сети
networkctl list                     # List all interfaces / Список интерфейсов
networkctl status <INTERFACE>       # Interface details / Детали интерфейса
networkctl lldp                     # Show LLDP neighbors / Показать LLDP соседей

Sample Output:

IDX LINK   TYPE     OPERATIONAL SETUP
  1 lo     loopback carrier     unmanaged
  2 enp0s3 ether    routable    configured

Reload Configuration

sudo networkctl reload              # Reload all configs / Перезагрузить конфигурации
sudo systemctl restart systemd-networkd  # Restart service / Перезапустить сервис

Network Configuration Files

DHCP Configuration

/etc/systemd/network/20-wired.network

[Match]
Name=enp0s3  # Interface name / Имя интерфейса

[Network]
DHCP=yes  # Enable DHCP / Включить DHCP

sudo systemctl restart systemd-networkd  # Apply config / Применить конфигурацию

Static IP Configuration

/etc/systemd/network/20-wired.network

[Match]
Name=enp0s3

[Network]
Address=192.168.1.100/24  # Static IP / Статический IP
Gateway=192.168.1.1       # Gateway / Шлюз
DNS=8.8.8.8               # DNS server / DNS сервер
DNS=8.8.4.4

Multiple IP Addresses

/etc/systemd/network/20-wired.network

[Match]
Name=enp0s3

[Network]
Address=192.168.1.100/24
Address=192.168.1.101/24  # Second IP / Второй IP
Address=2001:db8::1/64    # IPv6 / IPv6 адрес
Gateway=192.168.1.1
DNS=8.8.8.8

Static Routes

/etc/systemd/network/20-wired.network

[Match]
Name=enp0s3

[Network]
Address=192.168.1.100/24
Gateway=192.168.1.1

[Route]
Destination=10.0.0.0/8    # Route to 10.0.0.0/8 / Маршрут к 10.0.0.0/8
Gateway=192.168.1.254     # Via gateway / Через шлюз

Advanced Networking

Bridge Configuration

Step 1: Create bridge device / Создать устройство моста

/etc/systemd/network/10-bridge.netdev

[NetDev]
Name=br0  # Bridge name / Имя моста
Kind=bridge

Step 2: Configure bridge / Настроить мост

/etc/systemd/network/20-bridge.network

[Match]
Name=br0

[Network]
Address=192.168.1.100/24
Gateway=192.168.1.1
DNS=8.8.8.8

Step 3: Add interface to bridge / Добавить интерфейс в мост

/etc/systemd/network/30-bridge-member.network

[Match]
Name=enp0s3  # Physical interface / Физический интерфейс

[Network]
Bridge=br0  # Add to bridge / Добавить в мост

sudo systemctl restart systemd-networkd  # Apply / Применить

Bond (Link Aggregation)

Step 1: Create bond device / Создать устройство bond

/etc/systemd/network/10-bond.netdev

[NetDev]
Name=bond0
Kind=bond

[Bond]
Mode=active-backup  # Bond mode / Режим bond
PrimaryReselectPolicy=always
MIIMonitorSec=100ms

Step 2: Configure bond / Настроить bond

/etc/systemd/network/20-bond.network

[Match]
Name=bond0

[Network]
Address=192.168.1.100/24
Gateway=192.168.1.1

Step 3: Add interfaces to bond / Добавить интерфейсы в bond

/etc/systemd/network/30-bond-member1.network

[Match]
Name=enp0s3  # First interface / Первый интерфейс

[Network]
Bond=bond0
PrimarySlave=true  # Primary member / Основной член

/etc/systemd/network/30-bond-member2.network

[Match]
Name=enp0s8  # Second interface / Второй интерфейс

[Network]
Bond=bond0

VLAN Configuration

Step 1: Create VLAN device / Создать устройство VLAN

/etc/systemd/network/10-vlan10.netdev

[NetDev]
Name=vlan10
Kind=vlan

[VLAN]
Id=10  # VLAN ID / VLAN ID

Step 2: Configure VLAN / Настроить VLAN

/etc/systemd/network/20-vlan10.network

[Match]
Name=vlan10

[Network]
Address=192.168.10.100/24

Step 3: Attach VLAN to parent / Привязать VLAN к родительскому интерфейсу

/etc/systemd/network/30-parent.network

[Match]
Name=enp0s3  # Parent interface / Родительский интерфейс

[Network]
VLAN=vlan10  # Attach VLAN / Привязать VLAN

Troubleshooting & Tools

Common Issues

# Interface not managed
networkctl status <INTERFACE>  # Check interface status / Проверить статус
sudo systemctl restart systemd-networkd  # Restart service / Перезапустить

# DNS not resolving / DNS
sudo systemctl enable --now systemd-resolved  # Enable resolved / Включить resolved
sudo ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf  # Link resolv.conf / Привязать resolv.conf

# Configuration not applying
sudo networkctl reload  # Reload configs / Перезагрузить конфигурации
journalctl -u systemd-networkd --no-pager | tail -50  # Check logs / Проверить логи

Debug Mode

sudo systemctl edit systemd-networkd --full  # Edit service file / Редактировать файл сервиса
# Add: Environment=SYSTEMD_LOG_LEVEL=debug
sudo systemctl daemon-reload  # Reload daemon / Перезагрузить демон
sudo systemctl restart systemd-networkd  # Restart with debug / Перезапустить с отладкой
journalctl -u systemd-networkd -f  # Watch debug logs / Смотреть отладочные логи

Verify Configuration Syntax

sudo systemd-analyze verify /etc/systemd/network/*.network  # Verify syntax / Проверить синтаксис

Comparison Tables

systemd-networkd vs NetworkManager

Bond Modes

📚 Documentation Links

• systemd.network Man Page