Hello!

If i have an MT router with for example 2 interfaces, and i want that
users behind interface one:

without public ip: pass with nat (hotspot auth)
with public ip: pass with their own ip

the ip of the NAT (interface two) should be at the same domain as the customers fixed ip

i don want to use bridge.

so 1:1 mapping or what is the solution?

tahnks fors help Gabor

1:1 NAT might be a solution for you,
as well static NAT rules for each client,
http://wiki.mikrotik.com/wiki/How_to_li ... Local_ones