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Cygiwn's sshd, 2 tunnels and file transfer fails
- From: "Michael Wiedmann" <michael dot wiedmann at aastra dot com>
- To: <cygwin at cygwin dot com>
- Date: Fri, 6 Jan 2012 14:42:26 +0100
- Subject: Cygiwn's sshd, 2 tunnels and file transfer fails
Given the following test scenario:
+-----------+ +-----------------+ +-----------+
| Client #1 | | Server (XP/7) | | Client #2 |
| - ssh | 1) | Cygwin/sshd | 2), 3) | - ssh |
| - httpd +-------->+ +<----------+ |
+-----------+ | | +-----------+
+-----------------+
1) client #1 initiates a ssh connection to cygwin/sshd _and_
requests "remote port forwarding" like:
-R 60000:client_#1_ip:80 server_ip
This works w/o any problems
2) client #2 initiates a ssh connection to cygwin/sshd _and_
requests "local port forwarding" like:
-L 1234:127.0.0.1:60000 server_ip
This works w/o any problems
3) client #2 accesses httpd on client #1 using 127.0.0.1:1234
This works for "simple" web browsing
But if client #2 tries to upload "large" files, e.g. like:
curl -X PUT -d @file.txt http://127.0.0.1:1234/uploaddir/file.txt
to client #1's httpd this fails after transferring only a small
part of the file.
The ssh connection itself is not affected and stays intact.
It looks like the TCP congestion/overload control mechanism of the
two TP streams does not work properly in this case.
Testing the same scenario using a Linux sshd this works w/o any
problems.
Is this a known problem of Cygwin?
Any known workaround?
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