Re: SFTP client via PASE, large files possibly timing out

Paul,

The 'set timeout' in Expect makes perfect sense. That didn't occur to me before seeing your recent messages, but it makes a lot of sense.

Expect is not part of SSH (like SFTP is). It is a generic program that pretends to be a user at a terminal, and automates what the user might do... so it keys in values, and sits and waits for responses to be sent to the "screen" (the virtual screen it's reading under the covers, not your actual display) and based on what it sees on the screen, it does something in response, etc. It can be used to automate any user interaction with a PASE command-line environment.

So if you've written your script to timeout during a put/get command, it makes perfect sense that it's killing the file transfer when the timeout occurs. It doesn't know what the command is doing under the covers, it only knows what's displayed to the screen.

So, my question to you... why code expect to do a timeout during the actual put/get command? are you having trouble with it 'freezing' during file transfers and never completing?

Sorry this response was a bit slow... I was out of the office for a few days.

-SK




On 11/14/2015 11:43 AM, Steinmetz, Paul wrote:

Scott,

Those were settings recommended to check by IBM support.
By increasing "Set Timeout" from 30 to 90 included in the .expect input script, I was successful in resolving this issue.
I tested using higher values, successful up to 296.
297 and higher fails.
Why is this?
I'd like to confirm for future for large files or when times are longer.

Paul

-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Scott Klement
Sent: Friday, November 13, 2015 12:49 AM
To: Midrange Systems Technical Discussion
Subject: Re: SFTP client via PASE, large files possibly timing out

Paul,

Unless I'm misunderstanding your symptoms, you're looking at the wrong settings, here...

My understanding is that your file transfer is looking good, transferring data successfully until all of the sudden, mysteriously, the transfer is cut off after 45 seconds.

But, you are checking things related to "inactivity". Inactivity means that NOTHING is sent for the timeout period. Inactivity would never cut you off in the middle of a file transfer that's progressing!

I know the timeout settings are set higher, but let's use 45 seconds as an example to explain what 'inactivity' timeouts mean... if you had an inactivity timeout of 45 seconds that was affecting you, this is what would happen: (1) You'd start the transfer. (2) At some point (maybe right away, or maybe several minutes later) the transfer would "freeze"
where no new data was transfering for some reason like a network glitch or something. (3) 45 seconds after freezing up -- which is to say, 45 seconds without a single byte being transferred -- the timeout would
kick in and disconnect you. If the transfer never froze up, the
timeout would never occur (even if the file took hours to send)

That's what an inactivity timeout is... it means things are stalled.
Nothing at all is transferred in the timeout period, not even a single byte. As long as at least one byte is sent in that 45 seconds, it would not occur.

However, that's not how I understand your symptom. I understood that it was cutting you off while the transfer was successfully going.. So unless i'm misunderstnading, what you're experiencing cannot be an inactivity timeout. It's a timeout that occurs even on an active session... right?

The 4 settings you mentioned, however...

1- an INACTIVITY timeout on your router.

2- Keepalive... this is completely unrelated.

3- FTP server settings -- completely unrelated, you are not using FTP.
Even if you were, it's not the server.

4- SSH is the right tool to check for settings on... but again, this is an INACTIVITY timeout.

Unfortunately, I have no clue what would cause the issue you're seeing.
I've never seen this happen before. But, unless the session _is_
stalling for 45 seconds, this isn't an "inactivity" timeout. It's a "you only have 45 seconds total to use this connection before I cut you off" timeout, which is very different.

It's like saying to your teenaged daughter "you can only be on the phone for 10 minutes per day". (Time limit) That's very different from "as long as you say at least one word every 10 minutes you can stay on the phone, but if you don't say anything for 10 minutes i'll cut you off"
(inactivity timeout)




On 11/12/2015 2:03 PM, Steinmetz, Paul wrote:

I discovered a new piece to this puzzle.
For this one specific remote server:
All files are successful that complete in 45 seconds or less.
All files taking longer than 45 seconds fail.

Somewhere, there must be a 45 second timer/timeout setting.
These have been checked and confirmed.

1- It could be at the firewall/router's idle timeout level. - 5 minutes.
2- Verify the TCP keepalive on the iSeries (CHGTCPA). - TCP keep alive . . . . . . . . . 5
3- General FTP Server Inactivity Timeout Value see the following doc: The default inactivity timeout value is 300 seconds. The default transfer timeout value is 420 seconds. Inactivity timeout . . . . . . . 300
-http://www.ibm.com/support/docview.wss?uid=nas8N1011178
4- Timeout in SSH: Disconnecting Inactive SSH Sessions on the IBM I The TMOUT and TIMEOUT PASE environment variables have a value of 600 seconds. If there is no activity within an SSH session for 10 minutes
-http://www.ibm.com/support/docview.wss?uid=nas8N1013311

Paul


-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of
Scott Klement
Sent: Tuesday, November 03, 2015 4:39 PM
To: Midrange Systems Technical Discussion
Subject: Re: SFTP client via PASE, large files possibly timing out

FWIW.. I have used sftp to send extremely large files, such as whole server backups, without any problems at all. I did not have to set up anything in particular, it just worked.

When you are having trouble with your larger files (imho, 110mb isn't really very big) does it always stop at the exact same byte position?
Or does it vary?

If it varies, I'd suggest this is probably a network issue rather than a software issue. A flaky cable/switch/router/etc is causing the data to get screwed up somewhere, causing the transfer to abort.

IF it's always the same, then I would look for some sort of size limit being set up somewhere, most likely on the server-side.

Also, you could also try using scp rather than sftp and see if that matters at all. Just as a lark...


On 11/3/2015 8:34 AM, Steinmetz, Paul wrote:

I changed the SFTP process to send a 3mb zip file instead of the 110mb uncompressed file.
SFTP now working with a zipped 3mb file.
Large file issue for SFTP still exists, possibly 30 to 40mb limit.
Still looking to resolve this issue.

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