Subject: Access to 1.2.8 from 2.0.6

From: Mark Lane <[email-masked]>
Date: Fri, 16 Aug 1996 08:29:08 -0400

Hi, everyone.
        I recently installed a Debian 1.1 system with the 2.0.6 kernel.  I
couldn't have asked for a smoother install from a Windoze package, so
kudos to the development team!  Had one glitch with Majordomo 1.93,
but that's another e-mail sometime :)  Now, onto the real problem....
        I am having problems accessing data (ie. mail, web, etc.) on the
Debian host from Mac/FreePPP and Win95 PPP clients of my preexisting 
(prehistoric?) Slakware 1.2.8 host.  Win31/Trumpet clients work just fine
(MTU576/MSS536).  For example, I can establish PPP from a Win95 client 
into the Slakware box, TELNET into the Debian box, type 'ls /tmp', and get a 
file listing (not much stuff).  However, if I transfer more data (ie.'ls
/etc' or 
'w'), the output hangs.  I cannot retrieve web pages from the Slakware 
server.  Anything that appears to transfer much data back to the PPP client 
(through the Debian host) hangs.  All this *seems* to work fine going the 
other way (PPP to Slakware then access Debian), but I haven't tested 
enough to be sure (at 2am things get fuzzy).  I suspect a MTU/MSS 
problem.
        The only odd thing I can see is a difference in the maximum segment 
size on the Debian host from the Slakware.  Slakware shows MTU of 576
and MSS of 512 for PPP devices, where Debian shows 576 for both.  Same
for the ethernet device (1500MTU on both, 1436MSS on Slakware and
1500MSS on Debian).  I used ifconfig to change the MSS on the eth0
device on Debian (didn't know how to do the same on PPP devices) and
recompiled the kernel to disable MTU path disocovery to no avail.  I'm at
a loss, and hope someone on this list has already come across this.  I can
send any configs or test results necessary to diagnosis.  I'd sure appreciate
any insight out there on this!
                                                                        Than
k you,
                                                                        Mark
--------------------------------------------------------------------
Mark S Lane ([email-masked])   |
3rd Wave Technologies           |
Phone/FAX: (423) 652-6090       |

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From: [email-masked]
Date: Mon, 19 Aug 96 16:22:31 -0400

Here's a message that I originally sent to some Linux ISP mailing
lists.  I believe that it may be suitable for this list.

  Russell Coker

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From: [email-masked]
Date: Sun, 18 Aug 96 22:17:56 -0500
To: [email-masked], [email-masked]
Subject: Re: [linux-support] Access to 1.2.8 from 2.0.6
In-Reply-To: <[email-masked]> Cc: bofh

In <[email-masked]>, on 08/17/96 at 01:57
AM,
   Mark Lane <[email-masked]> said:

  I am having a problem which may be related.  I'm running a small ISP and
an Internet cafe.  I have 2 servers a Debian system and a Slackware
system.  Dial-up users who are unfortunate enough to be using Windows 3.1
and trumpet or Win95 are the only ones affected (users of OS/2, Linux, and
NT have no problems).  What happens is that when they establish a TCP
connection to the debian system data will be transferred very slowly.  I
have both the Slackware and Debian systems running as PPP servers and no
matter which one the poor Windows user connects to they will get very poor
throughput when transferring data to the Debian system.  So if a user
connects via PPP to the Debian system and then transfers data to the
Slackware system then everything will be fine.  Obviously the Debian
system is routing IP packets correctly, but there is some problem with TCP
(could be MSS).
   I have taken the Debian system from version 0.96R3 (a.out) with kernel
~1.3.60 to 1.1 (ELF) with kernel 2.0.13 and it made no difference.  If you
know what I could do (or even some useful tests I could run to get more
information) then please let me know.

>        I recently installed a Debian 1.1 system with the 2.0.6 kernel. 
>I couldn't have asked for a smoother install from a Windoze package, so
>kudos to the development team!  Had one glitch with Majordomo 1.93, but
>that's another e-mail sometime :)  Now, onto the real problem....
>        I am having problems accessing data (ie. mail, web, etc.) on a
>pre-existing (prehistoric?) Slakware 1.2.8 host from Mac/FreePPP and 
>Win95 PPP clients of the Debian  host.  Win31/Trumpet clients work just 
>fine.  For example, I can establish a PPP connection from a Win95 client
>into the Debian box, TELNET into the Slakware box, type 'ls /tmp', and
>get a file  listing (only a few files).  However, if I transfer more data
>(ie.'ls /etc' or 'w'), 
>the output hangs.  I cannot retrieve web pages from the Slakware server,
>nor access mailboxes NFS-mounted on Debian from Slakware.  Anything  that
>appears to transfer much data back to the PPP client (through  the Debian
>host) hangs.  All this *seems* to work fine going the other way  (PPP to
>Slakware then access Debian), but I haven't tested enough to be  sure (at
>2am things get fuzzy).  I suspect a MTU/MSS problem.
>        The only odd thing I can see is a difference in the maximum
>segment  size on the Debian and Slakware hosts.  Slakware shows MTU of
>576 and MSS of 512 for PPP devices, where Debian shows 576 for both. 
>Same for the ethernet device (1500MTU on both, 1436MSS on Slakware and
>1500MSS on Debian).  I used ifconfig to change the MSS on Debian's eth0
>device (didn't know how to do the same on PPP devices) and recompiled the
> kernel to disable MTU path disocovery to no avail.  I'm at a loss, and
>hope  someone on this list has already come across this.  I can send any
>configs  or test results necessary to diagnosis.  I'd sure appreciate any
>insight out  there on this!
>                                                                        Th
>k you,
>                                                                        Ma

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