[Vpn-help] Windows 7 x64 connecting to Cisco - periodic dropped packets/connection

Louie snikrep at gmail.com
Wed Sep 9 00:59:03 CDT 2009


I'm running Windows 7 x64.  Have tried following Shrew versions:

2.1.5-rc2
2.1.5-rc3
2.2.0-alpha9

On all of them, I'm running into a problem where packets are
periodically dropped while running NXClient.  I'm connecting to some
sort of Cisco ipsec gateway (not sure exact model) - and have no
problem connecting, getting DNS, etc.

Problem reliably arises when I attempt to use NXClient (a remote
desktop for Linux) that uses some sort of SSH link, if I'm not
mistaken.  The machines will *connect*, and the desktop appears - but
periodically (every 10-60 seconds), the connection will drop for one
or two ping cycles (I'm continually pinging the machine in a separate
window as a test).  It will only drop the pings for 2-3 attempts, then
the connection always returns.  I've also tried using regular Windows
RDP over the connection, and that also seems to trigger the freezes
(but not as often).

During the dropped/frozen connection, it appears to extend to the
entire VPN link, as I've tried pinging other machines - and they also
drop during these times.

I've attempted to adjust the MTU settings in the Shrew client (could
only find one spot where they could be set, assume it's right one?).
Tried values starting from the default of 1380 (??), all the way down
to about 500 - didn't appear to make a difference.

I have no problems with the Cisco VPN client (on a Windows 32-bit
machine), or with the NCP client on the x64 machine (which I'm using
now on trial).

I've searched through the archives to no avail - found something about
SSH problems associated with a hardcoded MTU value about a year ago,
but from the conversation, it appears that bug was fixed a while back.
 Intuitively this seems like some sort of MTU issue, because it's
randomly periodic, but could be wrong.

A gut feeling - it seems to reliably happen when I'm attempting to
move a lot of things in NXClient (i.e. more network activity),
otherwise if I leave things alone it eventually happens, just less
often (probably during periodic syncs).

Appreciate any help or ideas.



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