C:\MIX\firebird\fb25>C:\MIX\firebird\fb25\bin\isql /3255:e25
Database:  /3255:e25
SQL> create user u25a password '123';
SQL> create user u25b password '456';
SQL> commit;
SQL> exit;

C:\MIX\firebird\fb25>C:\MIX\firebird\fb25\bin\gbak -b /3255:C:\MIX\firebird\fb25\sec25.fdb sec25.fbk

C:\MIX\firebird\fb25>copy sec25.fbk C:\MIX\firebird\fb30\*.* 
Скопировано файлов:         1.

cd C:\MIX\firebird\fb30\

C:\MIX\firebird\fb30>gbak -c sec25.fbk /3333:C:\MIX\firebird\fb30\sec25.fdb

-- далее остановил службу ФБ-3, после чего:

C:\MIX\firebird\fb30>copy SEC25.FDB security3.fdb
Скопировано файлов:         1.

-- Запускаю службу ФБ-3, хочу пролезть в базу:
C:\MIX\firebird\fb30>C:\MIX\firebird\fb30\isql /3333:e30 -user u25a -pas 123
Statement failed, SQLSTATE = 28000
Your user name and password are not defined. Ask your database administrator to set up a Firebird login.
Use CONNECT or CREATE DATABASE to specify a database
SQL>

-- Запускаю службу ФБ-3, хочу пролезть в базу:
C:\MIX\firebird\fb30>C:\MIX\firebird\fb30\isql /3333:e30 -user u25a -pas 123
Statement failed, SQLSTATE = 28000
Your user name and password are not defined. Ask your database administrator to set up a Firebird login.

C:\MIX\firebird\fb30> findstr /r /c:"^[^#;]" firebird.conf | sort
AuthClient = Legacy_Auth,Srp,Win_Sspi
AuthServer = Legacy_Auth,Srp
DeadlockTimeout = 1
ExternalFileAccess = Restrict C:\MIX\firebird
FileSystemCacheThreshold = 65536K
LockHashSlots = 22111
MaxUnflushedWrites = -1
MaxUnflushedWriteTime = -1
MaxUserTraceLogSize = 99999
RemoteServicePort = 3333
Servermode = Super
TempCacheLimit = 2147483647
TempDirectories = c:\temp
UdfAccess = Restrict UDF;C:\WINNT\system32
 UserManager = Legacy_UserManage r
WireCrypt = Disabled