Isso soa como o seu problema. Eu encontrei neste artigo intitulado: Guia VPN do Gnome Network Manager Desativado (acinzentado) .
trechodoartigo
TheAddtabisgreyedoutwhenrequiredpluginsarenotinstalledforGnomeNetworkManager.ThefollowingpluginsshouldbeinstalledunderDebian/UbuntuLinux:
- network-manager-openvpnandnetwork-manager-openvpn-gnome-networkmanagementframeworkOpenVPNpluginGNOMEGUI
- network-manager-pptpandnetwork-manager-pptp-gnome-networkmanagementframeworkPPTPpluginGNOMEGUI
- network-manager-strongswan-networkmanagementframeworkstrongSwanipsecvpnplugin
- network-manager-vpncandnetwork-manager-vpnc-gnome-networkmanagementframework(VPNCpluginGNOMEGUI)
Toinstallalloftheabovepluginsusetheapt-getcommandasfollows:
$sudoapt-getinstallnetwork-manager-openvpnnetwork-manager-pptp\network-manager-pptp-gnomenetwork-manager-vpnc
ThefollowingpluginsshouldbeinstalledunderRHEL/Fedora/CentOS/ScientificLinux/RedHatEnterpriseLinuxdesktopsystems:
- NetworkManager-openvpn:NetworkManagerVPNpluginforOpenVPN
- NetworkManager-pptp:NetworkManagerVPNpluginforpptp
- NetworkManager-vpnc:NetworkManagerVPNpluginforvpnc
Toinstallalloftheabovepluginsusetheyumcommandasfollows:
$sudoyuminstallNetworkManager-vpncNetworkManager-pptp\NetworkManager-openvpn
Now,youcanaddvpnconnectiontoyoursystemusingNetworkManageritself.YoumayneedtorestarttheNetworkManagerasfollows:
$sudoNetworkManagerrestart