[Qemu-devel] interesting tftp experiments

[Qemu-devel] interesting tftp experiments

[Christian MICHON]

Hi,

since I was able on a windows host to connect (but no transfer)
on a ftp server over slirp, I thought I could do the same:
over slirp, connect to a true tftp server, not the layer provided
in slirp/tftp.c

In order to do so, I had to do minor patches to v0.7.0
- remove reference to tftp in vl.c
- remove reference to tftp in slirp/udp.c
- remove tftp.o linkage

By doing so, I have a ~true~ tftp-over-slirp qemu. I tried it
and yes I can READ & WRITE to a small tftp server I
found for windows host (http://tftpd32.jounin.net).

I still have some problems though. When the read or
write command is sent, it apparently somehow jams
the slirp channel. The read or write happens, but
not immediately (around 2 sec delay). 

The bad news is that so far, I've manage per session
of qemu either one write, or one read. If someone
has the knowledge of what could be wrong in this
part of slirp, please correct the flaws of what I just
found out.

At least, we should be able to transfer back and
forth files lesser than 32M.

-- 
Christian

Re: [Qemu-devel] interesting tftp experiments

[CoMiKe]

> since I was able on a windows host to connect (but no transfer)
> on a ftp server over slirp, I thought I could do the same:
> over slirp, connect to a true tftp server, not the layer provided
> in slirp/tftp.c

Hi!

I've never got problems connecting to an FTP server placed on my host computer.

Probably your problem is a port problem.
You have to options:

- If connecting on PORT mode in your FTP client, port 20 should be
redirected to your QEmu session through the -redir option.
- If you use passive mode on your FTP client (PASV) you don't need to
redirect any ports to QEmu, because in passive mode, the server is the
one that opens the port for data communication.

I'm using an small FTP server for Windows (SlimFTPd,
http://www.whitsoftdev.com/slimftpd/). It has an Apache like config
file, and total size is 51 Kb. It supports both PORT and PASV mode.

Probably you already knew about all this FTP topics, excuse me in that case.

Best Regards.
CoMiKe

Re: [Qemu-devel] interesting tftp experiments

[Christian MICHON]

> Probably your problem is a port problem.

this was a possibility

> You have to options:
> 
> - If connecting on PORT mode in your FTP client, port 20 should be
> redirected to your QEmu session through the -redir option.

interesting, never heard of it. Makes sense.

> - If you use passive mode on your FTP client (PASV) you don't need to
> redirect any ports to QEmu, because in passive mode, the server is the
> one that opens the port for data communication.

I already tried that, no success.

> 
> I'm using an small FTP server for Windows (SlimFTPd,
> http://www.whitsoftdev.com/slimftpd/). It has an Apache like config
> file, and total size is 51 Kb. It supports both PORT and PASV mode.

we've a winner here! this ftpd for windows host is working fine. I
don't even need to redirect the port. Thanks alot :))))))

Christian

Re: [Qemu-devel] interesting tftp experiments

[Henrik Nordstrom]

On Tue, 28 Jun 2005, CoMiKe wrote:

> - If connecting on PORT mode in your FTP client, port 20 should be
> redirected to your QEmu session through the -redir option.

This is supposed to work "automagically". Sounds like the slirp FTP 
"emulation" code has gone missing somehow...

> - If you use passive mode on your FTP client (PASV) you don't need to
> redirect any ports to QEmu, because in passive mode, the server is the
> one that opens the port for data communication.

If you FTP to the virtual host address (10.0.2.3) then the slirp FTP 
"emulation" code still needs to fix up the addresses used..

I haven't used the user-net networking of qemu much as I have my qemu:s 
running with tun/tap networking to the host, but a lot of this worked just 
fine when I used slirp in it's original form some years ago for providing 
dialup access.

Regards
Henrik

Re: [Qemu-devel] interesting tftp experiments

[Henrik Nordstrom]

On Mon, 27 Jun 2005, Christian MICHON wrote:

> over slirp, connect to a true tftp server, not the layer provided
> in slirp/tftp.c
>
> In order to do so, I had to do minor patches to v0.7.0
> - remove reference to tftp in vl.c
> - remove reference to tftp in slirp/udp.c
> - remove tftp.o linkage

You shouldn't need to do this if you tftp to the hosts real address, only 
if you insists on using the virtual slirp tftp address..

Regards
Henrik