Subject: Re: Odd problem FTPing via nat/ppp?
To: None <>
From: Olaf Seibert <>
List: current-users
Date: 09/02/1998 12:46:00
In <B2122E09-15BA4F@> "Bruce Anderson" <> writes:

>On Tue, Sep 1, 1998 4:57 PM, William O Ferry <mailto:WOFerry+@CMU.EDU>
>>     I recently moved, and have been working on getting my systems up. 
>> One machine has a modem and a static IP so it is set up for
>> demand-dialing PPP, and also running NAT for the other systems.  The
>> setup is working fine, with one exception.  There is one file that
>> consistantly fails to download, either via FTP or HTTP.  I was
>> eventually able to download it by FTPing it to another account I have,
>> gzipping it, then FTPing it to my local systems.  But it seems to me
>> that a certain data pattern must confuse PPP or NAT or something.
>That some thing might be the modem on the other end intercepting
>data that resembles the "AT" attention command (PlusPlusPlus)contained in
>your data file.  This happened with my ISP. The modems were stripping
>attention commands. If this is the case you should be able to test it
>for you self.
>1) Choke ftp with that file.
>2) Can you still do some web surffing or get you mail or other ftp's?
>   If "Yes" then the problem is the ISP's modem.

Around the offset in the file that was mentioned (0x4988) there are only
a lot of zeroes. So while the theory is a good one, it does not seem to
apply here (unless the IP headers are part of the problem).

As a data point: I downloaded the file on NetBSD 1.2, with its ftp
client, and that worked without problems. I am not behind NAT of any
sort on this machine.

___ Olaf 'Rhialto' Seibert - rhialto@polder.ubc. ---- Unauthorized duplication,
\X/ ---- while sometimes necessary, is never as good as the real thing.