RE: VPN & PPPoE

[Paul Gaskin <paul () midwesttechnologies com>]

Is there a sure fire way to come up with a good MTU speed? 
We used one in the Microsoft Knowledge Base. and came up with an MTU of 1366
and this didn't seem to do the trick. 
Also, We had a concern with setting the MTU really low. How is this going to
effect the way other files get transferred?
Will setting the MTU lower effect the speed of the DSL (surfing the web,
downloading files)?

Thanks 

Paul





-----Original Message-----
From: Keith T. Morgan [mailto:keith.morgan () terradon com]
Sent: Tuesday, January 21, 2003 9:15 AM
To: Paul Gaskin; security-basics () securityfocus com
Subject: RE: VPN & PPPoE


We had to deal with this very issue using IPSEC via Free S/Wan on linux.
The solution was to kick the interface (pppoe facing) MTU down to the 1280
range.  This was after some experimentation.  Play around with the MTU and
you should be able to get it to work.  If you have a sniffer handy on the
client machine, watch to see how much fragmentation is occuring on the
interface.  Lots of fragmentation seemed to break IPSEC for us.

-----Original Message-----
From: Paul Gaskin [mailto:paul () midwesttechnologies com]
Sent: Friday, January 17, 2003 4:29 PM
To: 'security-basics () securityfocus com'
Subject: VPN & PPPoE


I am new to the list and I'm not sure if this even falls into this category
but I'm getting desperate!

We have set up a VPN and it seems to work fine everyone can log on and move
around the network and send and receive email. 

One person though... on a DSL using PPPoE can not send e-mail. we have tried
everything... has anyone run into this problem? 

the user is on a Windows XP laptop connected to a Linksys wireless router
(Using PPPoE). and Outlook for E-mail. 

Any help would be greatly appreciated 

Thanks in advance 

Paul