Re: [squid-users] Squid and VPN, not working!!!

Hi Aknit,

I've had quite a similar issue with a VPN user not being able to connect
through my squids.

In the end the problem was that the client and the VPN concentrator somehow
messed up
the MTUs, especially one option called 'IP path MTU discovery'.

The final solution was to disable IP path MTU discovery on the squid boxes
and it worked.

If your squid is running on Linux, please try:

echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc
if there is such a file in your proc fs... - or look for something similar.

Torsten

aknit44@globenetcafe.net on 07.10.2001 13:03:33

Please respond to aknit44@globenetcafe.net

To: squid-users@squid-cache.org
cc:
Subject: [squid-users] Squid and VPN, not working!!!
                                                                            
                                                                            
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hi list... how u all doing...

well, i have quite a complicated situation.. i am setting up a connection
to the internet using a VPN tunnel, and RADIUS.. here is the network
layout...

1. requesting user with Windows 98 VPN client

2. pass-thru via multi-homed Windows 2000 Server running Remote Access
Server and Routing VPN server, connected to Windows 98 segment and Linux
masquerader segment

3. authenticated by RADIUS server located on the Windows 2000 Server and
masquerader segment

3. masqueraded thru a linux box using IPChains and two network cards onto
the public internet

4. connection to the cisco router gateway and then redirected back to squid
server, transparently....

now, here is how it works... a user on the Windows 98 box launches MS-VPN
client which is configured to connect to the Windows 2000 Server box.. the
Win2k box then uses its Remote Access and Routing server to send Radius
Auth and Accounting packets to the RADIUS server on its second network
interface...

the authentication goes well, and the Windows 98 user is authenticated and
connected, then assigned an IP on the Linux masquerader network,
effectively using VPN to localise the user....

now, when it comes to using the internet, the Windows 98 user can connect
to all local web servers and other non-HTTP services anywhere.. the problem
comes when the user sends an HTTP request to a non-local domain, such as
www.yahoo.com or www.cnn.com... the user can resolve the domain name, and
connect to the site, but can't download any content.. the connection just
sits there, hanging, and waiting, and nothing happens....

we had a feeling it might have something to do with squid, so we disabled
the transparent redirect on the router, and voila, we were able to connect,
albeit without squid, which meant a little slower... when we re-enabled
squid, we got the same problem again....

upon running sniffer, we saw that the windows 98 box makes several
re-transmissions.... and then becomes considered an un-responsive
station....

could anyone have any idea why this connection doesn't work with the squid
enabled...?.. even with squid IPs defined in the browser, same problem...
does the IP change squid does to the packet make the return packet null and
void to the windows 98 user..?..

all help will be appreciated.. thanks...

AKNIT

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Received on Sun Oct 07 2001 - 22:56:46 MDT