Server and Client Sockets: how to test three-way handshake?

Hello all,

I'm testing a Server/Client socket in C. At the same time I'd like to
see my packets go through the network and for that I'm using Ethereal.
As you may know, Ethereal doesn't work in loopback way, so I looked for
a different solution:

I have my server socket in my Windows machine, and the client socket in
a Lunix machine at a certain university. They communicate each other
through port 9877. But the communication seems to fail.

I understand it is something about the firewall. I opened up my windows
firewall for port 9877 though I think the Linux machine (for which I
don't have administrator rights) is still shut down from outside access.

What do you think should I do? Is there a way to give the socket in the
Linux machine the rights (user/password) to access to/from outside w/o
being an administrator? I have to connect to this university Linux
machine with SSH...

Thanks for your help,

FBM

PS. I just installed the MS Loopback Adapter, but I havent' tried it yet.

Fernando Barsoba wrote:
> Hello all,
>
> I'm testing a Server/Client socket in C. At the same time I'd like to
> see my packets go through the network and for that I'm using Ethereal.
> As you may know, Ethereal doesn't work in loopback way, so I looked for
> a different solution:
>
> I have my server socket in my Windows machine, and the client socket in
> a Lunix machine at a certain university. They communicate each other
> through port 9877. But the communication seems to fail.
>
> I understand it is something about the firewall. I opened up my windows
> firewall for port 9877 though I think the Linux machine (for which I
> don't have administrator rights) is still shut down from outside access.
>
> What do you think should I do? Is there a way to give the socket in the
> Linux machine the rights (user/password) to access to/from outside w/o
> being an administrator? I have to connect to this university Linux
> machine with SSH...
>
> Thanks for your help,
>
> FBM
>
> PS. I just installed the MS Loopback Adapter, but I havent' tried it yet.

SSH has the ability to tunnel other ports through. You could have
the client listen on 127.0.0.1:9877 and relay the TCP to
127.0.0.1:9877 on the server machine. Then you just connect your
client app to your loopback address.

$ ssh -L 9877:127.0.0.1:9877 myuser@myhost


Steve

Steve Horsley wrote:
> Fernando Barsoba wrote:
>
>> Hello all,
>>
>> I'm testing a Server/Client socket in C. At the same time I'd like to
>> see my packets go through the network and for that I'm using Ethereal.
>> As you may know, Ethereal doesn't work in loopback way, so I looked
>> for a different solution:
>>
>> I have my server socket in my Windows machine, and the client socket
>> in a Lunix machine at a certain university. They communicate each
>> other through port 9877. But the communication seems to fail.
>>
>> I understand it is something about the firewall. I opened up my
>> windows firewall for port 9877 though I think the Linux machine (for
>> which I don't have administrator rights) is still shut down from
>> outside access.
>>
>> What do you think should I do? Is there a way to give the socket in
>> the Linux machine the rights (user/password) to access to/from outside
>> w/o being an administrator? I have to connect to this university Linux
>> machine with SSH...
>>
>> Thanks for your help,
>>
>> FBM
>>
>> PS. I just installed the MS Loopback Adapter, but I havent' tried it yet.
>
>
> SSH has the ability to tunnel other ports through. You could have the
> client listen on 127.0.0.1:9877 and relay the TCP to 127.0.0.1:9877 on
> the server machine. Then you just connect your client app to your
> loopback address.
>
> $ ssh -L 9877:127.0.0.1:9877 myuser@myhost
>
>
> Steve

If I understand correctly, you suggest to use loopback for client &
server. In other words, execute the processes on the same machine. The
thing is I want to see the packets going through with Ethereal, and
that's not possible using loopback addresses (even with MS Loopback
Adapter). I must run the sockets on two different machines.

But it seems that you may be onto something... Perhaps I can connect
both processes using SSH... though no idea how to do that.

Regards,

Fernando