From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jerry Van Baren <gerald.vanbaren@smiths-aerospace.com>
Date: Wed, 5 Jan 2005 08:54:50 -0500
Subject: [U-Boot-Users] U-Boot & FTP
In-Reply-To: <20050105004655.3CCBCC108D@atlas.denx.de>
References: <20050105004655.3CCBCC108D@atlas.denx.de>
Message-ID: <41DBF1AA.1020803@smiths-aerospace.com>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

Wolfgang Denk wrote:
> Dear Tolunay,
> 
> in message <41DB36C9.3080807@orkun.us> you wrote:
> 
>>I can think of one case where FTP would be desirable. If the host is 
>>behind a stateful firewall and TFTP Server is on the other side, the 
> 
> 
> I'm not sure if it is a good idea to attempt to  run  TFTP  across  a
> firewall. If you need a firewall, you don't want to have TFTP traffic
> running through it.
> 
> 
>>client might not be able to access the TFTP server properly. Because per 
> 
> 
> How about using NFS?
> 
> 
>>but I can see it may be needed by some. A very basic lightweight and 
>>tight TCP support could be developped for FTP support. There are some 
>>TCP implementations for really limited resource hosts.
> 
> 
> I didn't say it is impossible. It's just unlikely to be added.
> 
> Best regards,
> 
> Wolfgang Denk

Wolfgang has higher standards than most of us ;-) and thus has not had 
the "pleasure" of working with Windows.  With Windows XP SP2 
firewalling, TFTP loading using a Windows box as the server breaks by 
default because the firewalling blocks the u-boot TFTP inbound requests.

Our customer requested, and I plan to implement Real Soon Now, that the 
u-boot TFTP source port be configurable: my plan is to make an 
environment variable:
* If set, use that port as the u-boot source port
* If not set, use the current method of using a pseudo random port

Our customer will modify their TFTP server so that it blindly starts the 
TFTP transfer using the pre-configured target IP address and UDP port. 
This will have the effect of "punching through" the XP firewall, 
allowing the remainder of the TFTP transfer to proceed normally.

This is ugly and requires a preconfigured, known system (but can be 
aided by some extra knowledge like a DHCP configuration request just 
occurred therefore a TFTP load is going to happen Real Soon Now) BUT it 
does allow our customer to provide a system that _their_ customer 
doesn't need to know how to modify firewall rules.

...and that is how the Dumbing Down of the World occurs :-(.

I will provide a patch when I get it working and I will understand 100% 
if Wolfgang rejects it.  Perhaps we can use the SourceForge "upload 
patch" feature to store patches that a few people find useful but are 
not of general use and are rejected by Wolfgang.

gvb