Stuck in Red Hat Enterprise Linux server-land for so many years, I didn't have to deal with NetworkManager. But now I'm doing some work with kvm/qemu which requires me to have the latest and greatest kvm/qemu, which requires me to get bleeding edge on my Linux distribution because mismatches between your kernel version and the userland tools can cause some weird issues, like seemingly random kernel panics where old tools don't fill out new fields and system calls end up randomly crashing (this should never happen, BTW, the kernel should check all inputs and reject any calls that would result in a kernel panic, but I have first-hand proof that this is happening). And bleeding edge either Ubuntu or Fedora means you get to deal with NetworkManager.
By and large folks who have a single network card plus a single WiFi adapter in their Linux box and don't intend to do anything unusual will have no problems with NetworkManager. But I wanted to set up a configuration that was unusual. My Linux server has two gigabit NIC's in it. One goes out to the corporate network. I wanted the other to be a direct connection to the Ethernet port on my Macbook Pro, and then have the two be bridged so it also appears I'm directly on the corporate network. I also wanted to set up a private non-routed VLAN tied to the specific network port between my Macbook Pro and the Linux server so I could set up a private network for file sharing between the two systems -- it's still far more pleasant to do editing, email, word processing, etc. on the Mac and use the Linux box as just a big bucket of bytes. Netatalk is not perfect but works "good enough" for this particular application.
All of this is functionality that Red Hat Enterprise Linux had implemented correctly by RHEL4 days (I know that because I backported most of the RHEL4 stuff to RHEL3 to get all of this functionality working in RHEL3 back in the old days for the Resilience firewalls). That is, we're talking about things that have worked correctly for over six years. Unless -- unless you're using a system that has its network cards managed by NetworkManager, at which point you're SOL unless you disable NetworkManager, because the system absolutely refuses to bring up bridges and vlans if you have NetworkManager enabled.
So my first inclination was to simply take an axe to NetworkManager and go back to the old way of doing things, which as I point out has been working for years. That is, "rpm -e NetworkManager". At which point I find out that half of bloody Gnome seems to have a dependency upon NetworkManager, albeit two dependencies removed, and while Gnome is evil it's the lesser of two evils (hmm, sounds like politics there, eh?). So, I settled for the simple way of disabling it:
- # chkconfig NetworkManager off
- # service NetworkManager stop