not all hostings provides this functionality, but "cracking" cod2 server so everyone can join is done by replacing cod2mp.exe with cracked one, but most server providers wont let you change the startup file of the game, so search for cod2mp.exe on ftp server of your cod2 server or if the server runs on linux u must look for linux start up file..
Ok so to clarify, I did what @WitchKing_TR said and i replaced cod2_inxed with cod2_inxed file which @bandiii92 posted. Nothing happened so i tried to restart server - i thought maybe if i do it changes will apply but server couldnt restart so i reinstalled it.
Still can't crack it properly ;/
Yes i tried with like another 5 cracked cod2_inxded files ;(