[转]Ubuntu 网络链接的标志没有的解决办法

當由ubuntu 8.04升級到8.10(Intrepid)時，發現在面板上的NetworkManager applet不見了(NetworkManager applet is missing)
如果在Terminal執行nm-applet時，會出現下列的錯誤訊息

    ** (nm-applet:7559): WARNING **: applet_dbus_manager_start_service(): Could not acquire the NetworkManagerUserSettings service as it is already taken. Return: 3

    (nm-applet:7559): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed

解決方式如下：

    * Fix nm-applet can't execute error

    1. 修改/etc/dbus-1/system.d/NetworkManager.conf 和 /etc/dbus-1/system.d/nm-applet.conf
    將下列紅色字，如果為deny，改allow
    <policy context=default>
    <allow own="org.freedesktop.NetworkManager"/>
    <allow send_destination="org.freedesktop.NetworkManager"/>
    <allow send_interface="org.freedesktop.NetworkManager"/>
    </policy>

    2. 重新啟動 dbus
    sudo /etc/init.d/dbus restart

    * Fix nm-applet "No connection defined" error

    3. 停止 NetworkManager
    sudo /etc/init.d/NetworkManager stop

    4. 刪除 /etc/network/interfaces 或是更名(rename)
    sudo rm /etc/network/interfaces

    5. 重新啟動 NetworkManager
    sudo /etc/init.d/NetworkManager start

6. 執行nm-applet

Reference:
https://bugs.launchpad.net/ubuntu/+source/network-manager-applet/+bug/249404
http://ubuntuforums.org/showthread.php?t=963335&page=3

（本人在ubuntu 10.04 下已经试过，可以解决问题，故贴出来跟大家分享一下）

原文地址 http://www.pczpg.com/a/2010/0130/439.html

补充：有时候我把 NetworkManager kill掉然后在重新开启也可以。