Is there, especially when you are unconscious, a further possibility to protect against possession except the defense-roll you have according to RAW? If i look at it, it doesn´t seems that mages can defend against unwilling possession better than mundanes.

Other than wards, mana barriers and FAB, I can't really think of any decent defense.

Hmmm...in this case possession-traditions are even stronger (compared to materialization) than expected.

Channeling requires the mage to willingly be possessed but doesn't require the spirit to belong to the mage being possessed.
Channeling doesn't have a prerequisite of being a possession tradition.
Therefore, learn channeling and after letting the spirit in you can enjoy the buffs as you geek the summoner.

The spirit could still act against you with spirit powers and depending on how your GM interprets the wording of channeling the spirit may can fight for physical control of the vessel. If it uses spirit powers on you you're considered a single dual natured entity so it also hits itself.

(Channeling is on p54 of Street Magic. Possession is on p101 of Street Magic.)

In general no, magicians don't have any natural advantages over mundanes in terms of resisting possession but then why would they? They're no better at resisting spells, for instance. However, they do tend to have higher ratings in the resisting attributes and access to wards and mana barriers as mentioned above.

Also, a magician can summon his own spirit(s) to guard his unconscious form. At the very least a watcher spirit or three can keep lookout.

I bet you could design a booby trap – anchor a Slay Spirit spell with a proximity/contact trigger, something like that?

The best defence of all, though, is to be possessed by a friendly spirit already.

Maybe I am missing something but doesnt possession require the body of a person to be taken into a lodge of equal force as the spirit and take days to do?

If your out of your body long enough for it to be possessed you have some major issues already.

No, what you are thinking about is inhabitation.

-CJ

What defenses does a Dragon have against possession?

Well, other than being a frakin' DRAGON. A really high willpower!

Ahh right, cheers for that.

Not much defense, If you are a mage you can order a spirit to intercept and stop possetion by kicking the hell out of the possessing spirit in the Astral plane when it tries to get you.

Hmmm.... p. 54, "Channeling is a metamagic power developed by possession tradition mages to enhance their control of spirits.."

And p. 95, "...an initiate conjurer can use Channeling metamagic (p.54) to exercise even more control when a spirit he summoned has possessed his body."

That sure sounds to me like only Possession tradition mages can use it.

The one exception is I think an ally spirit can be materialization, possession, or inhabitation regardless of your tradition. But you may rule that you are limited to materialization-or-inhabitation or limited to possession-or-inhabitation based on your tradition.

You might rule that non possession traditions can't take channeling and that may be balance, I don't know.