Vlad Khorsun wrote:

>> First: sorry for a looooong report!
>> I don't even know if this is the best group to post in - maybe the
>> IBO group more relevant?
>> Or, maybe this is stuff for the developers?
>>
>>
>> We are using Firebird 1.5 SS on Windows, client application written
>> in Delphi with IBO.
>>
>>
>> Problem:
>> Clients is disconnected (connection is "lost").
>> I've no idea whether this is a Firebird problem, a firewall problem,
>> or something else.
>
> Do you use firewall ? Or some intermediate network hardware

between client and

> server hosts (such as switch or hub) ? Sometime brocken HW may cause such
> problems...

Yes, there is a firewall. The network is structured into "zones".
I'll ask if they can double check hardware (if possible). A fault in
a switch or firewall (or a misbehaving network adapter) could be
corrupting package, obviously.
Clients and db-server never had this sort of problem before the
network was restructured and some new boxes (internal firewall and
new switches) were installed.

>
>> The network people did some tracing to see what was going on - see
>> traces below.
>> The Firewalls are Juniper, and the trace program is called

WireShark (I think).

>> I hope the trace is of use (it's way beyond my knowledge).
>>
>> The problem with "lost connection" was observed during the trace.
>> Any hint toward solving the problem is appreciated.
>>
>> Remark:
>> I thought that the only port used would be 3050, but it looks like
>> some other port is used as well. In the trace below port 1887 seems
>> to be in use for something (in the second trace port 2225 is in
>> use). I don't know if this is of any importance, though.
> ...
>
> I didn't found any important info in trace, sorry

If you think more trace info would help, I will try to provide it. I
have a trace with about 80 frames where there are 2 instances of
"Malformed packet".

>
>> If it is a firewall problem, I would nevertheless like a comment on
>> the port numbers (1887 and 2225) and the "Malformed Packet"

bit. If possible.

>
> TCP\IP connection have two endpoints. Port number of server endpoint
> is fixed and good known (3050 in case of Firebird). Port number of client
> endpoint is choosen by OS and have no meaning.

Does the OS choose random port numbers? Doesn't this make it
difficult to specify (to the firewall) which ports to keep
open/accesible? Can a fixed port number be specified? Or, this is irrelevant?

>
> As for "Malformed Packet" bit... If some packet have wrong

content then connection

> will be terminated by Firebird with corresponding record in

firebird.log. In the worst case

> AV may happen (i don't remember if it was fixed in FB 1.5.5). But

i don't understand

> who is decided that packet is malformed - firebird or tracing sw ?

I don't know. Again, I'll have to ask the network group. And
recheck the Firebird log.


Thanks for answers and comments. I will discuss this with the
network group and see if they can come up with some new ideas (or
anything else!).



Regards,
Aage J.