Thanks for your answer.

I want to add details:

at firebird.conf
...
RemoteServicePort = 4050


at C:\WINNT\system32\drivers\etc\services
...
knetd 2053/tcp #Kerberos de-multiplexor
man 9535/tcp #Remote Man Server
#gds_db 3050/tcp
#interserver 3060/tcp

I think that there is no definition for gds_db and 3050/tcp. My
expection: Client cant connect becouse there is no
definition.

FB running on 4050.
Client (IBO Console) access directly to 4050.

I dont unserstand why ? (May be hidden UDP is at work)
How can i route clients connection to ports which i wish.

Many Thanks.