You should not trust in what normal people tell you about wild camping.
In Austria the restrictions depend of the laws of the Bundesland. The crowded area around Vienna for example is very restricted, remote areas are more free.
Usually it depends in Austria of the altitude. In high areas it could cost your life to walk down instead of camping in the mountains in some bad weather circumstances. And there wild camping is less restricted.
Each Bundesland has an own law. The Alpenverein can tell you about them. As well you can simply ask the foresters about rules and laws belonging your behaviour in forest and field.
In Germany we have Bundes Wald Gesetz and Bundes Naturschutz Gesetz and Landes Wald Gesetz and Landes Naturschutz Gesetz as well as local reglementstions.
If they don't point out their local reglementations by well visible signs, it isn't your fault if you don't know them if you pass through the community. Of course you should know the reglementations of the community you live in.
Landes and Bundes laws of course you should look in. And you should respect what is written in there but not what you think inside by your fear and own thoughts.
That means: Usually in German forests it isn't allowed to use a tent.
Most times nothing is written about bivvy bags. !!!
(But a Tarp probably is seen as a tent. The only tent the German state declares as a tent is the Bundeswehr tent and older german military tents, which had been technically more cotton tarps than a modern tent. And even the NATO PONCHO, a military rain coat, is constructed to use it as a emergency tent, the German language doesn't use here an equivalent for shelter. That poncho stays at the border, but is a follower of the tentsheeds of the first world war, which had been pretty similar.
A raincoat pulled over the entrance if the bivvy bag would be a rain coat, not a tent!
As you see, the situation is pretty delicate.
BUT:
What isn't forbidden is allowed!
In some Bundesland it isn't allowed to leave the forest ways during the night. That is the case in Schleswig Holstein, but as I am informed it isn't the case in Bavaria.
To inform yourself you have to look in the laws. I am not a loyer and can give here only my private opinion as far I understood the laws. Only a German loyer or forester is allowed to inform you officially about the situation regarding German laws about forest, nature and fields.
I tell you what's going on in practice, not what's officially allowed or forbidden, because it's forbidden to me to tell you something about German laws.
(That stupid neighbours who tell you it would definitely be not allowed to sleep in the forest, usually do something, that is not allowed. They aren't loyers or official persons like foresters or police and if they tell you you something about the law,they do something, what is absolutely against the law, far more forbidden than camping in the woods! My private opinion.)
Outside the forest you need a Landowners permission.
In Practice wild camping for longer times isn't tolerated without land owners permission. But to set up late and leave the place early in the morning is a usually tolerated tradition.
Mainly if the farmer comes to you and tells you you should leave you reached a state, where your point changes from your right to roam to an illegal status. In this moment you have to ask for pardon and you have to leave immediatly.
Of course, if a sign tells you "don't camp here" or "don't enter" or a closed fence means the same.
Uninformed people who misunderstand the laws think in Germany bushcraft and bivvying wouldn't be allowed.
But (in my private opinion, as far as I understand the German laws) the opposite is the case.
Only closed fences regulate your usual right to walk over green land and field and in German forests.
Inside the forest an in usual 100 meters distance to the forest it isn't allowed to light an open flame.
Inside the forest it isn't allowed to construct a tent.
Outside the forest it isn't allowed to light a fire where you set things like a corn field in danger.
On foreign land you have the right to walk if you don't destroy anything. Of course you can't walk over a field through the plants.
You have the right to enjoy your time in open German public or open private forest and farm land until the owner or an official person like policeman or forester tells you the opposite!
That's the point most people don't really understand.
As long as I don't construct a tent in a forest, as long as I don't enter areas that are closed with a fence or somehow else or are obviously private like a garden around a house, as long as I don't light a fire inside the forest or inside an area of 100 meters around it, as long I don't touch borders of rivers and lakes, as long as I don't set other goods in risk of fire, I am pretty free to do in Germany what I want to do as a bushcrafter.
Edit: Obviously land under nature protection must be respected. That we have to respect in the large Nature parks and National parks too!!!
