故障現象

執行 service network restart 時出現：

Shutting down interface eth0: Error: Device 'eth0' disconnecting failed: This device is not active [FAILED]
Bringing up interface eth0: Error: Connection activation failed: Device not managed by NetworkManager or unavailable [FAILED]

ifconfig 顯示網卡無 IP，網路完全不可用。

根因分析

NetworkManager 與傳統 network 服務衝突：NetworkManager 接管網卡管理，導致 network 服務無法控制介面，產生「not managed by NetworkManager」錯誤。

解決步驟

1. 停用並禁用 NetworkManager

chkconfig NetworkManager off
service NetworkManager stop

2. 啟用傳統 network 服務

chkconfig network on
service network start

3. 驗證網路恢復

service network restart
# 應顯示 [OK] [OK]
ifconfig eth0
# 應顯示 IP、UP BROADCAST RUNNING MULTICAST

完整操作日誌參考

[root@localhost Desktop]# service network restart
Shutting down interface eth0: Error: Device 'eth0' ... not active [FAILED]
...
[root@localhost Desktop]# chkconfig NetworkManager off
[root@localhost Desktop]# chkconfig network on
[root@localhost Desktop]# service NetworkManager stop
Stopping NetworkManager daemon: [OK]
[root@localhost Desktop]# service network start
Bringing up loopback interface: [OK]
Bringing up interface eth0: [OK]
RTNETLINK answers: File exists (多行，忽略即可)
[root@localhost Desktop]# service network restart
Shutting down interface eth0: [OK]
Bringing up interface eth0: [OK]
[root@localhost Desktop]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:A0:C6:44
inet addr:192.168.1.189 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
...

永久生效配置

1. 編輯網卡配置檔 /etc/sysconfig/network-scripts/ifcfg-eth0：
   NM_CONTROLLED=no # 明確告知 NetworkManager 不管理此介面
2. 重啟驗證：service network restart

Systemd 系統（CentOS 7+/RHEL 7+）對應指令

systemctl stop NetworkManager
systemctl disable NetworkManager
systemctl enable network
systemctl start network

何時保留 NetworkManager？

• 桌面環境、筆記型電腦、頻繁切換 Wi-Fi/有線/VPN
• 需要圖形化網路管理介面

伺服器環境建議停用 NetworkManager，改用傳統 network 服務或 systemd-networkd，配置更穩定可預測。

故障預防清單

• 安裝系統時選擇「最小安裝」，避免預設安裝 NetworkManager
• 使用 Kickstart/Ansible 自動化部署時明確禁用 NetworkManager
• 變更網路配置後務必 service network restart 驗證

遵循「停用 NM → 啟用 network → 驗證 → 固化配置」流程，即可徹底解決 Linux 伺服器網卡「not active」問題。