Con Interbase no sé, con Firebird lo puedes obtener con 'CLIENT_ADDRESS', aquí tienes un ejemplo que devuelve la IP y otros parámetros:
Código SQL
[-]SELECT RDB$GET_CONTEXT('SYSTEM', 'ENGINE_VERSION') AS engineversion,
RDB$GET_CONTEXT('SYSTEM', 'NETWORK_PROTOCOL') AS protocol,
RDB$GET_CONTEXT('SYSTEM', 'CLIENT_ADDRESS') AS address,
RDB$GET_CONTEXT('SYSTEM', 'DB_NAME') AS dbname,
RDB$GET_CONTEXT('SYSTEM', 'SESSION_ID') AS sesionid,
RDB$GET_CONTEXT('SYSTEM', 'TRANSACTION_ID') AS transactionid,
RDB$GET_CONTEXT('SYSTEM', 'CURRENT_USER') AS currentuser
FROM RDB$DATABASE;