On Mon, May 17, 2010 at 3:18 PM, Jon Schewe <jpschewe at mtu.net> wrote:
> I'm trying to capture some large files from my house (on Comcast) to a
> server out of state (not on Comcast). I'm copying the files using ssh
> and a non-standard port.Things are fine for files of a couple megabytes,
> but files over say 10 megabytes stall out part way through. One night I
> got 50MB uploaded all night! So today I started up tcpdump on both ends
> and captured the traffic. I noticed an interesting thing in wireshark
> when the connection stalled out. I got a "TCP Previous segment lost"
> message on the server side and then started getting "TCP Dup ACK" on
> both ends. The server has a SonicWall firewall in front of it and is
> virtualized with vmware. My house is using dd-wrt on a Linksys router as
> my connection. Is this Comcast doing it's filtering for our protection
> or is this just something misbehaving on either firewall?

Could very well be the Sonicwall.  I had to administer one of these
trash heaps before, the default timeout for stateful connections is
set to something useless.

I worked around it by creating an outbound rule for all TCP traffic
with a timeout of 120 minutes instead of the default (10?).  There's
also a setting (sorry, don't remember where) that adjusts the global
TCP settings, and they're WRONG, horribly wrong by default.

If I can find my Sonicwall documentation that I wrote, I'll post what
the exact TCP settings are and where to find them.  Your SSH session
issue sounds identical to what I saw when I was trying to set up my
first Sonicwall 3060 Pro.

Brian