Here http://bansky.net/echotool/
i found command line application that does exactly what i want, written in
C#, sure the same could be done in Delphi.
What?
On Sat, Mar 10, 2012 at 9:52 AM, Dmitri Tsvetikov <
dmitri.tsveti...@gmail.com> wrote:
> Hi,
> just experimenting...
> udp packet from machine 192.168.1.10 has ports (from WireShark dump):
>
> User Datagram Protocol, Src Port: ds-user (4403), Dst Port: cbt (7777)
>
> Machine 192.168.1.100 has Synapse receive socket port = 7777 and actually
> receives and displays this packet.
> What do i have in this packet that identifies the sender? IP =
> 192.168.1.10 and port = 4403.
> And receivers GetRemoteSinPort gives me 4403, and i send reply with IP =
> ...10 and destination port 4403.
> Echo reply:
>
> User Datagram Protocol, Src Port: pwgpsi (3800), Dst Port: ds-user (4403)
>
> But machine 192.168.1.10 do not know that it is supposed to accept packet
> with destination port 4403. That is the problem!
> I think windows Sockets is assigning those random numbers and Synapse is
> not aware of them.
> Mark, windows Sockets do not reject this packet with ICMP "destination
> port unreachable", it thinks the Synapse application is a legitimate
> destination.
>
> I tried GetLocalSinPort on the sender machine in a hope that it will give
> me this random 4403 port number.
>
> For now sender is incapable to receive echo, unless i specify some fixed
> port for answers, but that would not be echo then.
>
>
>
>
> On Sat, Mar 10, 2012 at 2:28 AM, Jorge Aldo G. de F. Junior <
> jagf...@gmail.com> wrote:
>
>> For sure you dont want to use getlocalsinport... this will say YOUR
>> local port not the remote one. You should use GetRemoteSinPort instead
>> to get the other end port...
>>
>> And if this fails yet, try calling getsins before reading the packet.
>>
>> 2012/3/9 Dmitri Tsvetikov <dmitri.tsveti...@gmail.com>:
>> > Thank you Lukas,
>> >
>> > i implemented your suggestions,
>> > now UDP_TxRx app. can receive messages (in a listening thread) from
>> > identical application on another computer.
>> >
>> > Next i tried to convert it to Terminal and Echo app.
>> > Echo works like this:
>> > Term sends packet:
>> > Internet Protocol Version 4, Src: 192.168.1.10, Dst: 192.168.1.100
>> > User Datagram Protocol, Src Port: ds-user (4403), Dst Port: cbt (7777)
>> >
>> > Echo app. receives this packet, displays and sends it back switching
>> source
>> > and destination ports like this:
>> > Internet Protocol Version 4, Src: 192.168.1.100, Dst: 192.168.1.10
>> > User Datagram Protocol, Src Port: pwgpsi (3800), Dst Port: ds-user
>> (4403)
>> >
>> > Terminal do not see this message, because it listens on the wrong port
>> > number.
>> >
>> > How can i get source port number of the sent packet (in Terminal app.)?
>> > I tried this:
>> > SndSock.Connect(edSndSockIP.Text, edSndSockPort.Text);
>> > if SndSock.LastError <> 0 then exit;
>> > Caption := Caption + ' ' + IntToStr(SndSock.GetLocalSinPort);
>> > SndSock.SendString(edStr.Text + #13#10);
>> > Caption := Caption + ' ' + IntToStr(SndSock.GetLocalSinPort);
>> > It returns 0. I was hoping to get something similar to 4403.
>> >
>> > Because this is the port that is supposed to listen for echo message.
>> >
>> > How to receive this echo packet?
>> >
>> > Best regards,
>> > Dmitri
>> >
>> >
>> >
>> > On Mon, Mar 5, 2012 at 11:29 PM, Lukas Gebauer <gebyl...@mlp.cz> wrote:
>> >>
>> >> > Returned packet seems in order. Is it possible that Synapse is just
>> >> > dropping the packet because there is something wrong? Could this
>> option
>> >> > be
>> >> > turned off temporarily?
>> >>
>> >> 1. Do not use "rcvsock.ConvertLineEnd := true;" on non-stream sockets.
>> >>
>> >> 2. Call of CreateSocket is not needed. Socket will be created
>> automaticky
>> >> by Synapse.
>> >>
>> >> 3. call of "sndsock.Bind('0.0.0.0', '0');" is not needed too. It is
>> >> default value.
>> >>
>> >>
>> >> --
>> >> Lukas Gebauer.
>> >>
>> >> http://synapse.ararat.cz/ - Synapse Delphi and Kylix TCP/IP Library
>> >> http://geoget.ararat.cz/ - Geocaching solution
>> >>
>> >>
>> >>
>> >>
>> >>
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