I want to mod a map so that all AIs are at permanent war with each other. I tried setting them at war with each other at start, but about 10 turns or so they declare peace. I tried modifying the war prob/rand a bit, but still didn't seem to affect them. Is this possible from the map XML or do I need to edit the AI diplomacy XML more?

If it's for a specific map (you load it as a scenario), you can set them to minor civs in the WB save file; this will make them at war, and unable to conduct diplomacy. In case you're unfamiliar with the WBsave, it's just a text document defining how to set up the map for a scenario. Toward the top all the of player information is defined for all the players. In the list of data for each player you'll see this:
MinorNationStatus=0
Set the minor nation status to 1, and that should accomplish exactly what you want.

Or turn on always war.

This is just for one map and a lot of type work, because you had to do it for ervery AI civ:sad:

Open the map-file with an editor and take a look.

BeginTeam
TeamID=3
Tech=TECH_MYSTICISM
Tech=TECH_MASONRY
ContactWithTeam=1
ContactWithTeam=2
ContactWithTeam=3
ContactWithTeam=4
ContactWithTeam=22
ContactWithTeam=33
AtWar=4
AtWar=33
PermanentWarPeace=4
RevealMap=0
EndTeam

Thanks Manifold, that's exactly what I was looking for. Time for some copy/paste.

yes, i am for the simple questions:)

Are you sure that will work Manifold? PermanentWarPeace as a game option refers to the fact the game locks in war or peace at contact, so I'd assume this like named variable in the WBS would require you to also set the team to at war with all players as well (else they'd be locked in peace with all civs they have contact with). Maybe that's what you're saying, in which case it's far simpler to use the MinorNationStatus, which is guaranteed to put that civ at war with everyone without the possibility of making peace.

not as a gameoption as part of the team entry. it is true, you can arrange always war or always peace in the wb-file. it works in my file, i am sure