[ale] stalled ftp/sftp transfers

[Pat Regan]

Ken Cochran wrote:
> "Local" network is Charter (cable).  Upload speed cruises along
> at some 50kb/s-ish for about an hour (hmm) & to about 135mb
> then it stalls.  

Snip, snip!

> Stalling happens on the firewall/NAT machine (directly
> connected to the WAN) with ncftp or the OS' (in this case
> FreeBSD) command-line ftp client and an OSX machine inside
> the NAT/firewall running its command-line ftp client.

It sounds like you've tried skipping the NAT on one side of the
transfer.  Since you haven't gotten any other solid ideas I'm going to
assume that you might have NAT and a port forward on the destination
side.  I have no idea if this will be helpful or not.

It is possible that your firewall's timeouts are too low.  I don't know
what you're using as a firewall on the destination side (if anything at
all).

My little openwrt router here at home seems to default to 3600 seconds
(1 hour) for
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_established.  My
laptop defaults to 432000 seconds.

3600 seconds is one hour.  If you're running a firewall on the remote
side and forwarding a port you may be hitting a timeout like this.
Especially if it consistently runs for precisely 1 hour before dying.

If you're running a non-linux firewall I don't have any more specific
information in my brain except that every NAT will have some sort of
timeouts built it.

Pat


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