Subject Re: [firebird-support] What is the difference between these connection strings?
Author Helen Borrie
At 11:50 p.m. 1/10/2014, brucedickinson@... [firebird-support] wrote:

>I know that I can connect to Firebird (on Windows) by specifying connection string in two ways:
>1. C:\MyDB.FDB
>2. localhost:C:\MyFDB.FDB
>I am speaking here about local connection.
>Is there any difference between these two connection strings?

Yes, indeed. The first (peculiar to Windows) is know as "Windows local protocol". Its workings depend on both the Firebird server version and the Windows platform.
-- in Firebird 1.5 and below, WLP uses a custom subsystem called IPServer and works only with Superserver and embedded. It won't work at all with Server2003 if Fb is running as a service.
-- in Firebird 2.0 and higher, WLP uses a subsystem called XNET. There are problems on some ServerXxxx platforms that may be resolved by setting the IpcName parameter in firebird.conf to Global/FIREBIRD (and deleting the hash symbol, of course). Changes in firebird.conf don't take effect until you stop and restart Superserver. Note, this solution has no effect on Fb 1.5 and below.

>I know that when I use localhost then TCP\IP protocol is used.

Kind of. The second string uses TCP Local Loopback, so, unlike a real TCP/IP connection, the messages never leave the local machine. You can Google this: it's available on all platforms. Note, the default ip address for localhost,, is/was unavailable on some distros of Windows. AFAIR, one actually has to add a parameter to the Registry to activate it. Again, Google will be your friend for checking and fixing this.

Also - contrary to Mark's comment - I don't believe port 3050 has to be open for a locahost connection to work.

>Is it possible that connection to database will become unavailable on some machines when I switch from first connection string to the second one?

Again, recalling ancient history and talking Superserver here, if a WLP connection via the old IPServer subsystem is active, I think other connections will be blocked until the WLP connection detaches. The other way around, if a TCP/IP connection is active, I seem to recall that an IPServer connection isn't blocked. But the best way for you to verify what's possible on your system is to test it.

Helen Borrie, Support Consultant, IBPhoenix (Pacific)
Author of "The Firebird Book" and "The Firebird Book Second Edition"