there are several different bass tracks in this song. 

the first one is 
g:-------------------------- 
d:-------------------------- 
a:-------------------------- 
D:--6--6--6--6/--2--2--2--2- 

then comes in 
g:-------------------11--9-9-----9-9-9-11-8- 
d:---10-10h-13----13------------------------ 
a:-0------------0--------------0------------ 
D:------------------------------------------ 

while this plays repeatedly 
g:-13--13--13--13-------- 
d:-13--13--13--13-------- 
a:----------------------- 
D:----------------------- 

after a while comes this riff 
g:-----13--13-----13---13--13-----13-- mess around with this one to 
d:---13------13----------13-----13--13 get it right. 
a:-11-----------11-------------------- 
D:------------------------------------