Subj : XP -> cablemodem -> DSL Router -> VSFTP running FC2 -> could not upload but could download
To   : comp.os.linux
From : dogatemycomputer
Date : Sat Aug 07 2004 12:02 am

Greetings,

First.. I should say I installed Linux for the first time about 3
weeks ago after finally going cold turkey from Windows XP.  The
positive support I have received from the community as a whole is
nothing less than impressive  So far I have had help setting up the
Fedora client, setting up dual monitor support with my Radeon 9700,
installing and configuring my Cisco VPN client, setting up remote
Desktop to connect back to the office, figuring out how to make
Entourage work well enough to give me Exchange access when required,
seting up Firefox, setting up VSFTP and an SSHD server.. etc..  
anyway.. to all you developers out there who have made it possible.. 
YOU ARE AWESOME!!!

To the problem..  I am using XP *groan* from the office with CuteFTP
through a pix firewall connecting to a Cox cablemodem with a DLink WAP
routed to a vsftpd and sshd with FC2.  I could connect to both the ftp
server and the ssh server from anywhere on the internet and download
files without a problem but I could not upload large files (larger
than 60k?) without the server timing out.

I finally identified the problem being the MTU setting on the XP
machine at the office.  I downloaded the following:

http://www.download.com/TZ-Connection-Booster/3000-2155-10225668.html?tag=lst-0-1

from download.com called TZ Connection Booster 1.1 from TrackZapper.

This application will allow you to set your MTU setting.  The trick is
to set the MTU setting exactly the same on the XP client as you have
it set on the DSL Router and the linux box.

To find your MTU setting on the linux box try:

su -l
enter the password
ifconfig

root@/root # ifconfig
eth2      Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx
          inet addr:xxx.xxx.xxx.xxx  Bcast:xxx.xxx.xxx.xxx 
Mask:xxx.xxx.xxx.xxx
          inet6 addr: xxxx:xxxx:xxxx:xxxx:xxxx/xx Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:235900 errors:0 dropped:0 overruns:0 frame:0
          TX packets:191939 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:129933514 (123.9 Mb)  TX bytes:28452539 (27.1 Mb)
          Interrupt:5 Base address:0xd800

This should show you the MUT setting (as defined above using
MTU:1500).

To find the setting the the average DLink router:
http://192.168.0.1 (or the ip address of your gateway)
userid: admin (or whatever)
password: <blank> (or whatever yours is set too)
click HOME from the tabs at the top
WAN from the tabs down the left
the MTU setting is probably the last configuration setting at the
bottom
change your MTU setting on your router to match your linux machine
Click APPLY
Your router should reboot

The default MTU for most dlink routers appears to be 1500.  I would
change this setting to match your linux box as I haven't figured out
how to change the MTU setting on my linux box yet.

Once you install TZ Connection Booster 1.1 from TrackZapper on your XP
box and walk through the configuration steps you'll see the MTU
setting in the menu list.  Simply change the MTU setting on your
XP/2000/ME/98 box to match your router and linux machine.  Reboot
after you have made the changes, login and connect back to your linux
machine.  You should then be able to upload files.

Thanks everyone who contributed to this fix!  I really appreciate it.
(I would give specific names but I read through hundreds of posts
explaining how FTP works before I figured out the solution.)

Have a great night!
Dave

.