I have a constant UDP connection from one office to another office. I use
it for an in-house application and it works just fine.

But, I want to add file transfer to my little app without requiring another
port be opened on the firewall and I don't want to reinvent the TCP wheel.

Is there a way to tunnel TCP through my existing UDP connection and take
advantage of the packet checks that TCP offers for transfering files?

Usually within LAN that be OK, TFTP ( UDP base ) work pretty nice for LANs,
but if you "reinvent the TCP wheel"
you need to use TCP, otherwise you can use 3-th party s/w which did that
Arkady

"smerf" <smerf@shroom.com> wrote in message
news:MsZXg.10453$nn6.9747@bignews6.bellsouth.net.. .
>I have a constant UDP connection from one office to another office. I use
>it for an in-house application and it works just fine.
>
> But, I want to add file transfer to my little app without requiring
> another port be opened on the firewall and I don't want to reinvent the
> TCP wheel.
>
> Is there a way to tunnel TCP through my existing UDP connection and take
> advantage of the packet checks that TCP offers for transfering files?
>
>
>

smerf wrote:

> Is there a way to tunnel TCP through my existing UDP connection and take
> advantage of the packet checks that TCP offers for transfering files?

Have a look at http://gray-world.net/pr_cctt.shtml

They say it can tunnel TCP inside UDP. I've not tested that.
There should be other tools that can do.

Cheers,
Armin

In article <MsZXg.10453$nn6.9747@bignews6.bellsouth.net>,
"smerf" <smerf@shroom.com> wrote:

> I have a constant UDP connection from one office to another office. I use
> it for an in-house application and it works just fine.
>
> But, I want to add file transfer to my little app without requiring another
> port be opened on the firewall and I don't want to reinvent the TCP wheel.
>
> Is there a way to tunnel TCP through my existing UDP connection and take
> advantage of the packet checks that TCP offers for transfering files?

How does this avoid opening another port on the firewall? You'll need
to open the port that's used for the TCP-over-UDP protocol, since it
will be different from whatever port you're using for your "constant UDP
connection" (I have no idea what you mean by that, BTW).

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***

In article <MsZXg.10453$nn6.9747@bignews6.bellsouth.net>,
smerf <smerf@shroom.com> wrote:
>I have a constant UDP connection from one office to another office. I use
>it for an in-house application and it works just fine.

>But, I want to add file transfer to my little app without requiring another
>port be opened on the firewall and I don't want to reinvent the TCP wheel.

>Is there a way to tunnel TCP through my existing UDP connection and take
>advantage of the packet checks that TCP offers for transfering files?

Yeh, you could do it, but the bother would be relatively high.
You'd probably find it a lot easier to just adapt one of the old
modem file transfer protocols such as x-modem.

"Barry Margolin" <barmar@alum.mit.edu> wrote in message
news:barmar-D0E4B5.00412215102006@comcast.dca.giganews.com...
> In article <MsZXg.10453$nn6.9747@bignews6.bellsouth.net>,
> "smerf" <smerf@shroom.com> wrote:
>
>> I have a constant UDP connection from one office to another office. I
>> use
>> it for an in-house application and it works just fine.
>>
>> But, I want to add file transfer to my little app without requiring
>> another
>> port be opened on the firewall and I don't want to reinvent the TCP
>> wheel.
>>
>> Is there a way to tunnel TCP through my existing UDP connection and take
>> advantage of the packet checks that TCP offers for transfering files?
>
> How does this avoid opening another port on the firewall? You'll need
> to open the port that's used for the TCP-over-UDP protocol, since it
> will be different from whatever port you're using for your "constant UDP
> connection" (I have no idea what you mean by that, BTW).

I simply mean that there is a UDP port open on PC1 and another UDP port open
on PC2 and that they are available and the apps hosting them are aware that
they are available for data transfer betwen the 2 PCs.

I don't have access to the other firewall, and may not be able to get the
admin to open an external TCP port without a tremendous gnashing of teeth
and perhaps some boils and a plague or two. So, I thought, why not tunnel
the TCP connections thru the UDP ports?

The idea here is similar to the Hamachi VPN solution (which LogMeIn
purchased and does not release the server code for). See
http://www.realvnc.com/pipermail/vnc...ry/053895.html for a
short description of how Hamachi encapsulated TCP in UDP.

I don't really understand all of what is needed to accomplish that. I
assume the Hamachi solution used an ethernet driver of some sort and simply
relayed the data sent to it to the other end of the tunnel via the UDP used
to get thru the firewalls and NATs.

Well, I can't code a device driver yet (no C++ skills), so I thought I might
be able to aim the TCP connections through my UDP tunnel.

Any ideas? I am looking into using WinPcap to sniff the packets on the
network and send them thru the UDP tunnel, but that may result in packets
being split (according to the referenced article) - and nobody wants split
packets.

The only WinPcap that I have found to use is wrapped in an activex control.
But, won't COM interop really screw with the speed if I do something like
this via an activex component from .Net?

Then there is the encrpytion of the data stream between the endpoints -
something I haven't even bothered to tackle at this point.

Does encryption + COM interop = too damned slow to bother with?

Thanks for the idea.

While researching it, the damndest thing happened. I thought of a simple
way to do file transfer via UDP. It involves my own little
protocol....small and simple but possibly more verbose than the TCP
protocols - so speed may suffer.

Now, I am on a hunt to enable other apps to work thru my little UDP tunnel -
like Remote Desktop or VNC or Video Conferencing etc..

To do this, I still need to find the best way to make my UDP connection on
each end act as a connecting point between the PCs. They would essentially
be TCP Proxies for any app that required a TCP connection.

Any ideas?


"Walter Roberson" <roberson@hushmail.com> wrote in message
news:b9jYg.139987$1T2.115593@pd7urf2no...
> In article <MsZXg.10453$nn6.9747@bignews6.bellsouth.net>,
> smerf <smerf@shroom.com> wrote:
>>I have a constant UDP connection from one office to another office. I use
>>it for an in-house application and it works just fine.
>
>>But, I want to add file transfer to my little app without requiring
>>another
>>port be opened on the firewall and I don't want to reinvent the TCP wheel.
>
>>Is there a way to tunnel TCP through my existing UDP connection and take
>>advantage of the packet checks that TCP offers for transfering files?
>
> Yeh, you could do it, but the bother would be relatively high.
> You'd probably find it a lot easier to just adapt one of the old
> modem file transfer protocols such as x-modem.

In article <3LjYg.16088$O65.15047@bignews5.bellsouth.net>,
smerf <smerf@shroom.com> wrote:
>Now, I am on a hunt to enable other apps to work thru my little UDP tunnel -
>like Remote Desktop or VNC or Video Conferencing etc..

>To do this, I still need to find the best way to make my UDP connection on
>each end act as a connecting point between the PCs. They would essentially
>be TCP Proxies for any app that required a TCP connection.

It'd be a small modification to any gre encapsulator.