SFTP errors after upgrade

Question

SFTP errors after upgrade

I've been trying to open SFTP connections to a known good OS X Tiger Server via BBEdit, CyberDuck and via command line on the terminal, and nothing is working. I get a "subsystem request failed on channel 0" error in Cyberduck and Terminal, but BBEdit just silently quits.

I can successfully SSH to this server, and as I indicated above I was able to SFTP prior to the upgrade. I can also SFTP to another FreeBSD server at my 3rd party hosting provider. Any thoughts on how to troubleshoot this? Is there some arcane .plist file I need to delete, or is this something exclusive to Tiger Server and Snow Leopard somehow?

Thankfully I have a web-based file browser as an alternative to securely transfer files to/from this server, but would far prefer a dedicated client if possible so curious if anybody else has experienced anything like this.

black MacBook, Mac OS X (10.6), 2 GB RAM

Posted on Aug 30, 2009 7:55 PM

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Answer 1

BobHarris

Level 9

56,933 points

Aug 30, 2009 8:10 PM in response to Bradley Paton


sftp -v -v -v username@good.sftp.server
sftp -v -v -v username@bad.sftp.server

compare the diagnostic output of the good vs the bad. Where they radically differ is most likely where the problem is happening.

If nothing else it might give you additional ideas.

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Answer 2

Aug 31, 2009 7:41 AM in response to BobHarris

Nothing jumps out at me. The only significant differences up to the point of failure are that the OS X Server box has a slightly older version of OpenSSH (1.99 vs. 2.0), and accepts a few more possible types of authentication (gssapi in addition to the standard publickey, password, keyboard-interactive). Otherwise there's some differences in kex parsekexinit (whatever that is), but it only appears to be a list of options that's slightly different between the two (different order for the values mostly).

Everything else looks identical up to the dis-connect:
debug2: channel input_statusconfirm: type 100 id 0
subsystem request failed on channel 0
Connection closed

The good server shows:
debug2: channel 0: rcvd adjust 2097152
debug2: channel input_statusconfirm: type 99 id 0
debug2: subsystem request accepted on channel 0
debug2: Remote version: 3
debug2: Server supports extension "posix-rename@openssh.com" revision 1
debug2: Server supports extension "statvfs@openssh.com" revision 2
debug2: Server supports extension "fstatvfs@openssh.com" revision 2
debug3: Sent message fd 3 T:16 I:1

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Answer 3

BobHarris

Level 9

56,933 points

Sep 1, 2009 5:43 AM in response to Bradley Paton

My next suggestion is to look in the "Tiger Server" log files


sudo more /var/log/secure.log
more /var/log/system.log

these are 2 most likely log files to contain sshd daemon log messages about ssh connection attempts.

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Answer 4

a brody

Level 10

85,314 points

Sep 1, 2009 5:53 AM in response to Bradley Paton

Fugu is an SFTP client that works very well within Snow Leopard:

http://rsug.itd.umich.edu/software/fugu/

Have you tried that?

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Answer 5

Sep 5, 2009 8:21 PM in response to BobHarris

Nothing in either file. The secure.log doesn't even log anything other than the SSH login I had to check the log files, even when I had opened a separate window and made a subsequent SFTP attempt. The system.log only registered the 2 sudo requests.

I tried Fugu as well below, and got no love there either. At this stage I'm just wondering if there is some very strange corruption at somewhere along the way, but not sure even how I could verify that. I tried to troubleshoot it on the client side by going into a new user account that had never previously had any sftp/ssh activity at that server, and as expected I got the requests to confirm the identity of the host and password for my user account, but after entering the password I got the same result.

This no longer appears to be a problem specific to Snow Leopard though, as just on a whim I logged into another Tiger Server (OS 10.4.11) on my local network and tried to sftp from there to the problem server, and got the same "subsystem request failed on channel 0" result.

The only things that I can think of now that could be at issue would be something attached to my specific user account, but I don't know what since I can SSH successfully, or something unique to my network, but given that I can SFTP to other servers from my network, I don't know what that would be either.

Whatever it is, I'm at a loss as to what to check from here.

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