[HLUG] when ever sending large emails drops my net connectiion - why

[Julian Robbins]

Hi Mark

Mark Broadbent wrote:
> Hi Julian,
>
> On 21/05/06, Julian Robbins <joolsr at fastmail.fm> wrote:
>> ...
>>
>> If I sent an email over roughly, 500k, my IPCop ADSL net connection 
>> drops.
>
> When you the connection drops, do you mean the actual ADSL modem
> connection or just the logical TCP/IP connection between you and the
> remote SMTP server dropped?
Actual ADSL modem connection drops.

>
>> I've no reason to suspect IPCop as this has been going on for many
>> months, and i think it would have been fixed if it were a specific issue
>> affecting IPCop.
>>
>> If i send the same mail via webmail its fine.
>
> Webmail running remotely on the internet or locally on your network?
Remotely, on the Internet, but attaching a local 500k file to an email.

>
>> I sent some tests via, my email smtp provider, fastmail.fm with and
>> without SSL. I also tried it with my ADSL provider Pro-net, same
>> problem, drops after getting only 21% through.
>
> I might of been tempted to say the IPCop box was proxying your email
> connections to do some sort of content/virus checking and has a file
> size limit.   But if you've tried using SSL then this would throw some
> warnings in Thunderbird about third party connection interceptions.
I don't think so. I setup IPCop myself, so i know hats in there in the main.

>
> Also does the connection stop at exactly the same point, do you know
> how much data has been transferred?

Note sure, though its seems pretty consistant .
>
>> I use IMAP with my email account, which is flawless apart from this.
>>
>> I'm using, FWIW Ubuntu Dapper, and Thunderbird 1.5.02, but I'm sure I
>> had same problems, running Breezy and older version of Thunderbird.
>>
>> IPCop has been there all the way along.
>
> Have you tried removing the IPCop box to check that isn't the cause.
I could try that, though I would have to get my adsl modem working 
directly, its a USB Fujitsu FDX310 type.
>
>> My only other inkling is could it be a MTU issue? we suspect Pro-net (or
>> their upstream provider) are doing strange things with MTU which might
>> cause issues, as we;ve had other strange ones occasionally.
>
> If the IPCop box is just routing your data (i.e. no proxying) then you
> can test this from your local machine by doing the following (on your
> local machine not the IPCop box):
>
> # ifconfig eth0 mtu 576
>
> and then test (I know the MTU is very small but it will go through any
> router at that size).
Well, it still goes wrong at about the same point, ie 28% the way 
through sending the mail.
I thought I had to change the MTU on IPCop for it to work though.
>
>> I haven't tried connecting with my windows laptop yet, thsi might at
>> least prove or disprove a couple of things.
Well, i just tried the same on my win laptop, and guess what ? worked 
fine!!.

This is via  a 11MBps WLAN connection, the linux pc, via a 100MBPS wired.

Julian


>
> Cheers
> Mark
>