RE: Missing messages

["Mark Smith" <mark.smith,AT,avcosystems,DOT,co,DOT,uk>]

One of my configurations is via low speed dialup, another through 150k
broadband, another through 600k ADSL.  All suffer the MTU problem when
routing traffic from machines behind the tunnel, all asymmetric in that
speed differs in one direction from the other.  In my case, part of it is
due to the differing upload/download speeds, part of it is the MTU issue.
I've resolved said issue on linux by clamping MSS forcefully, but haven't as
yet got around to hacking the Win32 client to make the same change.

Without said fix, both VNC and SMB fail to specific locations but work to
others, other services like SSH and I believe FTP work perfectly.
SSH-forwarded VNC to the failing locations works, which is pretty much what
convinced me that MTU was the issue, and fixing MTU made the problem vanish
instantly, proving it conclusively.  I cannot find any point of failure,
however, where ICMP (specifically fragmentation needed) is being dropped as
pings (ICMP echo request and ICMP echo reply) get through.

I have no idea if this helps, I'm just passing on information about my own
experiences.

--
Mark Smith - Avco Systems Ltd
email: mark.smith,AT,avcosystems,DOT,co,DOT,uk
Tel: +44 (0)1784 430996 Fax: +44 (0)1784 431078

-----Original Message-----
From: owner-cipe-l,AT,inka,DOT,de [mailto:owner-cipe-l,AT,inka,DOT,de Behalf 
Of
James Knott
Sent: 11 September 2003 17:44
To: CIPE
Subject: Re: Missing messages

I have now sent out all 6 dumps as separate text messages, with the
title "tcpdump...".  Let's see if they get through.

Also, has anyone else tried out my configuration.  That is using a dial
up ISP to connect via high speed access to a local network through a
firewall.  It would be nice to know what results you get.  I'm using Red
Hat 7.3 on all systems and cipe-1.4.5-9 on the notebook and firewall.
The same sort of problem also appears when trying to access my OS/2
system.  Both Allan and I are thinking that it's more of an SMB/IP
problem, rather than CIPE.

tnx jk

James Knott wrote:
> Do you know if there's a limit on message size?  The text only message
> was fairly long, and the messages with the attached files might be
> somewhat longer.  The files were plain text, with no extension in the
> filenames.  I'll have to try sending them separately, to see if they get
> through.
>
>
>
> Hans Steegers wrote:
>
>> Maybe, an attachment mailscanner is removing forbidden attachements.
>> I received the following file types via this mailing list, so they
>> must be
>> allowed: .txt .dat .bz2 .log .asc .eml .patch
>>
>> Do not use file extension associated with Microsoft, such as .doc, .xls,
>> etc.,
>> or with executables: .bat, .com, .exe, .pif, .scr, etc.
>>
>> It happened before that a message (without attachement) mysteriously
>> disappeared.
>
>
> I had noticed that earlier, with some other posts I made on another
> topic.  Also, about the same time this was happening, I was missing
> messages from other mail lists, apparently because my ISP was blocking
> messages sent to several addresses as "spam".  According to what someone
> else mentioned, they would classify a message as spam, if it was
> addressed to more than 35 subscribers.
>
>
> tnx jk
>
>
>
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