running custom maps .....modwarefare ?

[Jerry Zimmerman van Woesik]

This maybe a real stupid question to al lot of you guys here..... Sorry 
in advance !

I have been running a cod4 hardcore server from the day the linux bins 
came out.
Today I received a mail from a regular visitor. He asked if I could run 
some custom maps.
So I downloaded and installed some maps , but they don't work  :  need a 
mod to run custom maps. (or some message alike)
I started digging on the various sites, but I get more and more under 
the impression, that I have to run modwarfare to be able to load custom 
maps.
But I always thought that running a hardcore server did not include ANY 
mods .....not even modwarfare.

Can I run and hardcore server with modwarfare and still be ranked ? 
...... cause I always thought I couldn't.
However, after digging around on the net , it seems to me that that is 
the only way to run custom maps.....but I can't find any conclusive answer.

forgive me my ignorance.
Cheers
B4M