Re: AutoSSH problem

Re: AutoSSH problem

[Germain Le Chapelain]

On 06/01/18 23:03, René Berber wrote:
> The behavior looks normal.
>
> Quoting from the autossh man page:
>
> "Startup behaviour
>
> If the ssh session fails with an exit status of 1 on the very first try,
> autossh
>
> 1.' will assume that there is some problem with syntax or the connection
> setup, and will exit rather than retrying;
>
> 2.' There is a "starting gate" time. If the first ssh process fails
> within the first few seconds of being started, autossh assumes that it
> never made it "out of the starting gate", and exits. This is to handle
> initial failed authentication, connection, etc. This time is 30 seconds
> by default, and can be adjusted (see the AUTOSSH_GATETIME environment
> variable below). If AUTOSSH_GATETIME is set to 0, then both behaviours
> are disabled: there is no "starting gate", and autossh will restart even
> if ssh fails on the first run with an exit status of 1. The "starting
> gate" time is also set to 0 when the -f flag to autossh is used. "

Thank you for highlighting this point, René.

You are right: it "looks" normal, from far :)

However, looking closer to the log, you should see (or not, looking back 
at it it's not obvious) that I halted the connection the server about 
three minutes in:

> 2018/06/01 13:17:41 autossh[20680]: set alarm for 600 secs
> Connection to lanvaux.fr closed by remote host.
> 2018/06/01 13:20:52 autossh[20680]: check on child 4988

So something still doesn't line up. :/

I may try my dumpo-magic (I think it's actually called "DebugDiag", 
https://blogs.msdn.microsoft.com/chaun/2013/11/12/steps-to-catch-a-simple-crash-dump-of-a-crashing-process/)

But as said earlier it's probably going to poop (no pun intended) about 
AutoSSH being a cygwin program.


I will take a read on how debugging goes on Cygwin, or look at AutoSSH 
1.4e (and how to get it.)


Kindest regards,

Thank you for your answer!


-- 
Germain Le Chapelain
Lanvaux Computer Games Limited
http://lanvaux.fr


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AutoSSH problem

[Greg Freemyer]

On Thu, May 31, 2018, 4:58 AM Germain Le Chapelain <german@lanvaux.fr> wrote:
>
> Hi,
>
>
> I am experiencing troubles trying to set up a reverse SSH tunnel:
>
> I have installed AutoSSH as such:
>
> cygrunsrv.exe -I AutoSSH -p /bin/autossh -a "-M 20000 -R
> *:5900:localhost:5900 SMI@lanvaux.fr" -y tcpip --type auto -e
> AUTOSSH_NTSERVICE=yes
>
>
> Now, it works great, except if the ssh service at lanvaux.fr would
> become unavailable.
>
> In this case, the service stops.

If you're still having problems:

I've had it working for about 4 years.  I've set it up on at least 4
different windows PCs.  WIN7 and WIN10.

I changed jobs 6 months ago so I no longer have access to any of the computers.

But I did write-up my notes as a blog post:

https://lizards.opensuse.org/2015/04/20/using-opensuse-as-a-reverse-tunnel-site-for-windows-7-remote-desktop/

Key section of the write-up for your issue assuming your SSHD server is Linux:

===
4) Tweak the sshd_config on the server

By default openSUSE enables “AllowTcpForwarding” and “TCPKeepAlive”.
Verify they are either commented out or set to “yes” in
/etc/ssh/sshd_config

Set “GatewayPorts yes” and “ClientAliveInterval 300” in /etc/ssh/sshd_config.

Also make sure they are not commented out.

restart sshd to get the config values to be re-read:    sudo systemctl
restart sshd.service

===

Maybe that will help.
Greg

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Re: AutoSSH problem

[René Berber]

On 6/1/2018 10:31 AM, Germain Le Chapelain :

The behavior looks normal.

Quoting from the autossh man page:

"Startup behaviour

If the ssh session fails with an exit status of 1 on the very first try,
autossh

1.' will assume that there is some problem with syntax or the connection
setup, and will exit rather than retrying;

2.' There is a "starting gate" time. If the first ssh process fails
within the first few seconds of being started, autossh assumes that it
never made it "out of the starting gate", and exits. This is to handle
initial failed authentication, connection, etc. This time is 30 seconds
by default, and can be adjusted (see the AUTOSSH_GATETIME environment
variable below). If AUTOSSH_GATETIME is set to 0, then both behaviours
are disabled: there is no "starting gate", and autossh will restart even
if ssh fails on the first run with an exit status of 1. The "starting
gate" time is also set to 0 when the -f flag to autossh is used. "
-- 
R. Berber


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Re: AutoSSH problem

[Germain Le Chapelain]

Hi Andrew!


Thank you so much for the prompt answer,
> Hi. I'm glad someone is using autossh. I don't use it myself any more, and as a
> package maintainer it's impossible for me to tell if anyone else is.
Yes, it came up first in our research to establish a reliable reverse 
SSH-tunnel.

Is there a more common way?
I figure it would be a very common problem people have, especially with 
things like VNC.

I have also read about rstunnel ,but I don't know if it goes well on 
Cygwin and it was from AutoSSH so assumed AutoSSH improved on that :)
> SIGALRM?
I wouldn't know.  I was assuming some Windows thing.
Actually because the retry count in the log matched 14 I assumed it had 
to do with that.

I did glance at the AutoSSH code for a hard limit on 14 tries and indeed 
there are some #define of that but the default code path does seem to 
retry infinitely as you and I understood.

As you said it seemed like it crashed anyways.
> Yes, it should. But in this case it looks as though the service process crashed
> (around 10:44).
Yes!

So, sorry, it doesn't look like I put that precision in my first post:
The server AutoSSH was connecting to failed at that time.
It only got restarted a few hours later.

The first failure I was referring to right after was in the same 
circumstances.
The server also became unavailable.
(So you might even be able to reproduce the problem yourself.)

I just reproduced the issue with -e AUTOSSH_DEBUG=true.
The service started at 1:17

Here is the entire content of the AutoSSH.log file for the full test:

2018/06/01 13:17:41 autossh[20680]: checking for grace period, tries = 0
2018/06/01 13:17:41 autossh[20680]: starting ssh (count 1)
2018/06/01 13:17:41 autossh[4988]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:17:41 autossh[20680]: ssh child pid is 4988
2018/06/01 13:17:41 autossh[20680]: check on child 4988
2018/06/01 13:17:41 autossh[20680]: set alarm for 600 secs
Connection to lanvaux.fr closed by remote host.
2018/06/01 13:20:52 autossh[20680]: check on child 4988
2018/06/01 13:20:52 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:20:52 autossh[20680]: expired child, returning 1
2018/06/01 13:20:52 autossh[20680]: checking for grace period, tries = 0
2018/06/01 13:20:52 autossh[20680]: starting ssh (count 2)
2018/06/01 13:20:52 autossh[20680]: ssh child pid is 23648
2018/06/01 13:20:52 autossh[20680]: check on child 23648
2018/06/01 13:20:52 autossh[23648]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:20:52 autossh[20680]: set alarm for 410 secs
ssh: connect to host lanvaux.fr port 22: Connection refused
2018/06/01 13:20:54 autossh[20680]: check on child 23648
2018/06/01 13:20:54 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:20:54 autossh[20680]: expired child, returning 1
2018/06/01 13:20:54 autossh[20680]: checking for grace period, tries = 1
2018/06/01 13:20:54 autossh[20680]: starting ssh (count 3)
2018/06/01 13:20:54 autossh[17164]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:20:54 autossh[20680]: ssh child pid is 17164
2018/06/01 13:20:54 autossh[20680]: check on child 17164
2018/06/01 13:20:54 autossh[20680]: set alarm for 409 secs
ssh: connect to host lanvaux.fr port 22: Connection refused
2018/06/01 13:20:55 autossh[20680]: check on child 17164
2018/06/01 13:20:55 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:20:55 autossh[20680]: expired child, returning 1
2018/06/01 13:20:55 autossh[20680]: checking for grace period, tries = 2
2018/06/01 13:20:55 autossh[20680]: starting ssh (count 4)
2018/06/01 13:20:55 autossh[26428]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:20:55 autossh[20680]: ssh child pid is 26428
2018/06/01 13:20:55 autossh[20680]: check on child 26428
2018/06/01 13:20:55 autossh[20680]: set alarm for 408 secs
ssh: connect to host lanvaux.fr port 22: Connection refused
2018/06/01 13:20:56 autossh[20680]: check on child 26428
2018/06/01 13:20:56 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:20:56 autossh[20680]: expired child, returning 1
2018/06/01 13:20:56 autossh[20680]: checking for grace period, tries = 3
2018/06/01 13:20:56 autossh[20680]: starting ssh (count 5)
2018/06/01 13:20:56 autossh[20680]: ssh child pid is 8576
2018/06/01 13:20:56 autossh[20680]: check on child 8576
2018/06/01 13:20:56 autossh[8576]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:20:56 autossh[20680]: set alarm for 407 secs
ssh: connect to host lanvaux.fr port 22: Connection refused
2018/06/01 13:20:57 autossh[20680]: check on child 8576
2018/06/01 13:20:57 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:20:57 autossh[20680]: expired child, returning 1
2018/06/01 13:20:57 autossh[20680]: checking for grace period, tries = 4
2018/06/01 13:20:57 autossh[20680]: starting ssh (count 6)
2018/06/01 13:20:57 autossh[24208]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:20:57 autossh[20680]: ssh child pid is 24208
2018/06/01 13:20:57 autossh[20680]: check on child 24208
2018/06/01 13:20:57 autossh[20680]: set alarm for 406 secs
ssh: connect to host lanvaux.fr port 22: Connection refused
2018/06/01 13:20:59 autossh[20680]: check on child 24208
2018/06/01 13:20:59 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:20:59 autossh[20680]: expired child, returning 1
2018/06/01 13:20:59 autossh[20680]: checking for grace period, tries = 5
2018/06/01 13:20:59 autossh[20680]: starting ssh (count 7)
2018/06/01 13:20:59 autossh[18732]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:20:59 autossh[20680]: ssh child pid is 18732
2018/06/01 13:20:59 autossh[20680]: check on child 18732
2018/06/01 13:20:59 autossh[20680]: set alarm for 405 secs
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/06/01 13:21:13 autossh[20680]: check on child 18732
2018/06/01 13:21:13 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:21:13 autossh[20680]: expired child, returning 1
2018/06/01 13:21:13 autossh[20680]: checking for grace period, tries = 6
2018/06/01 13:21:13 autossh[20680]: sleeping for grace time 2 secs
2018/06/01 13:21:15 autossh[20680]: starting ssh (count 8)
2018/06/01 13:21:15 autossh[24260]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:21:15 autossh[20680]: ssh child pid is 24260
2018/06/01 13:21:15 autossh[20680]: check on child 24260
2018/06/01 13:21:15 autossh[20680]: set alarm for 390 secs
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/06/01 13:21:36 autossh[20680]: check on child 24260
2018/06/01 13:21:36 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:21:36 autossh[20680]: expired child, returning 1
2018/06/01 13:21:36 autossh[20680]: checking for grace period, tries = 7
2018/06/01 13:21:36 autossh[20680]: sleeping for grace time 8 secs
2018/06/01 13:21:44 autossh[20680]: starting ssh (count 9)
2018/06/01 13:21:44 autossh[20680]: ssh child pid is 25592
2018/06/01 13:21:44 autossh[20680]: check on child 25592
2018/06/01 13:21:44 autossh[25592]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:21:44 autossh[20680]: set alarm for 361 secs
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/06/01 13:22:05 autossh[20680]: check on child 25592
2018/06/01 13:22:05 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:22:05 autossh[20680]: expired child, returning 1
2018/06/01 13:22:05 autossh[20680]: checking for grace period, tries = 8
2018/06/01 13:22:05 autossh[20680]: sleeping for grace time 18 secs
2018/06/01 13:22:23 autossh[20680]: starting ssh (count 10)
2018/06/01 13:22:23 autossh[20680]: ssh child pid is 20644
2018/06/01 13:22:23 autossh[20644]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:22:23 autossh[20680]: check on child 20644
2018/06/01 13:22:23 autossh[20680]: set alarm for 322 secs
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/06/01 13:22:44 autossh[20680]: check on child 20644
2018/06/01 13:22:44 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:22:44 autossh[20680]: expired child, returning 1
2018/06/01 13:22:44 autossh[20680]: checking for grace period, tries = 9
2018/06/01 13:22:44 autossh[20680]: sleeping for grace time 32 secs
2018/06/01 13:23:16 autossh[20680]: starting ssh (count 11)
2018/06/01 13:23:16 autossh[20944]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:23:16 autossh[20680]: ssh child pid is 20944
2018/06/01 13:23:16 autossh[20680]: check on child 20944
2018/06/01 13:23:16 autossh[20680]: set alarm for 269 secs
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/06/01 13:23:38 autossh[20680]: check on child 20944
2018/06/01 13:23:38 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:23:38 autossh[20680]: expired child, returning 1
2018/06/01 13:23:38 autossh[20680]: checking for grace period, tries = 10
2018/06/01 13:23:38 autossh[20680]: sleeping for grace time 50 secs
2018/06/01 13:24:28 autossh[20680]: starting ssh (count 12)
2018/06/01 13:24:28 autossh[20680]: ssh child pid is 24784
2018/06/01 13:24:28 autossh[20680]: check on child 24784
2018/06/01 13:24:28 autossh[24784]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:24:28 autossh[20680]: set alarm for 198 secs
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/06/01 13:24:49 autossh[20680]: check on child 24784
2018/06/01 13:24:49 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:24:49 autossh[20680]: expired child, returning 1
2018/06/01 13:24:49 autossh[20680]: checking for grace period, tries = 11
2018/06/01 13:24:49 autossh[20680]: sleeping for grace time 72 secs
2018/06/01 13:26:01 autossh[20680]: starting ssh (count 13)
2018/06/01 13:26:01 autossh[20916]: child of 20680 execing /usr/bin/ssh
2018/06/01 13:26:01 autossh[20680]: ssh child pid is 20916
2018/06/01 13:26:01 autossh[20680]: check on child 20916
2018/06/01 13:26:01 autossh[20680]: set alarm for 105 secs
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/06/01 13:26:22 autossh[20680]: check on child 20916
2018/06/01 13:26:22 autossh[20680]: ssh exited with error status 255; 
restarting ssh
2018/06/01 13:26:22 autossh[20680]: expired child, returning 1
2018/06/01 13:26:22 autossh[20680]: checking for grace period, tries = 12
2018/06/01 13:26:22 autossh[20680]: sleeping for grace time 98 secs

The service was not running and the same error ("Signal 14") was 
reported on the event log at 1:27:46 PM
> If that doesn't help, then we may have to get more aggressive and use strace.

Thank you! I was wondering where to go next. I am looking forward to an 
education on the subject!

Hadn't you answered I would have tried a tool from Microsoft that 
watches after Services and saves a dump when a particular one crashes;

But I don't know if this work with Cygwin programs: I would have needed 
a pdb, then, to debug
I am not very familiar with software development in Cygwin, I will have 
a look at strace.


I also forgot to mention in my first post: did you note that the latest 
update to AutoSSH was about signals ? :p

I am willing to bet that installing the package 1.4e (I don't know how 
to do that, from the top if my head) will solve our issue.
Of course we would lose the other fixes that happened in it.


Thank you again for your reply!


Kind regards;

-- 
Germain Le Chapelain
http://lanvaux.fr



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Re: AutoSSH problem

[Andrew Schulman]

Hi. I'm glad someone is using autossh. I don't use it myself any more, and as a
package maintainer it's impossible for me to tell if anyone else is.

> I have installed AutoSSH as such:
> 
> cygrunsrv.exe -I AutoSSH -p /bin/autossh -a "-M 20000 -R 
> *:5900:localhost:5900 SMI@lanvaux.fr" -y tcpip --type auto -e 
> AUTOSSH_NTSERVICE=yes

That all seems correct.

> Now, it works great, except if the ssh service at lanvaux.fr would 
> become unavailable.
> 
> In this case, the service stops.
> 
> In the log viewer, I only get the following message in the system log:
> 
> The description for Event ID 0 from source AutoSSH cannot be found. 
> Either the component that raises this event is not installed on your 
> local computer or the installation is corrupted. You can install or 
> repair the component on the local computer.
> 
> If the event originated on another computer, the display information had 
> to be saved with the event.
> 
> The following information was included with the event:
> 
> AutoSSH: PID 8336: service `AutoSSH' failed: signal 14 raised

SIGALRM?

> and in autoSSH.log:
> 
> ssh: connect to host lanvaux.fr port 22: Connection timed out
> 2018/05/29 10:39:39 autossh[8424]: ssh exited with error status 255; 
> restarting ssh
> 2018/05/29 10:40:29 autossh[8424]: starting ssh (count 12)
> 2018/05/29 10:40:29 autossh[8424]: ssh child pid is 14616
> ssh: connect to host lanvaux.fr port 22: Connection timed out
> 2018/05/29 10:40:50 autossh[8424]: ssh exited with error status 255; 
> restarting ssh
> 2018/05/29 10:42:02 autossh[8424]: starting ssh (count 13)
> 2018/05/29 10:42:02 autossh[8424]: ssh child pid is 20004
> ssh: connect to host lanvaux.fr port 22: Connection timed out
> 2018/05/29 10:42:23 autossh[8424]: ssh exited with error status 255; 
> restarting ssh
> 2018/05/29 10:44:01 autossh[8424]: starting ssh (count 14)
> 2018/05/29 10:44:01 autossh[8424]: ssh child pid is 3056
> ssh: connect to host lanvaux.fr port 22: Connection timed out
> 2018/05/29 10:44:22 autossh[8424]: ssh exited with error status 255; 
> restarting ssh
> 2018/05/29 16:43:41 autossh[17172]: starting ssh (count 1)
> 
> (16:43:41 is when we manually restarted the service.)
> 
> From reading the AutoSSH manpage, I was expecting ssh to always try to 
> reconnect (except if it fails on the first try.)

Yes, it should. But in this case it looks as though the service process crashed
(around 10:44).

> When I noticed the first failure, I tried changing the service settings 
> for AutoSSH to restart all the time, but that didn't do it.
> 
> Am I missing something regarding AutoSSH configuration?

No, it seems like a bug. To find out more, please add "-e AUTOSSH_DEBUG=true" to
your service definition, and restart the service. autossh will send debugging
output to autossh.log. After the service fails again, post the log output here
from the last few minutes before it failed.

If that doesn't help, then we may have to get more aggressive and use strace.

Andrew


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AutoSSH problem

[Germain Le Chapelain]

Hi,


I am experiencing troubles trying to set up a reverse SSH tunnel:

I have installed AutoSSH as such:

cygrunsrv.exe -I AutoSSH -p /bin/autossh -a "-M 20000 -R 
*:5900:localhost:5900 SMI@lanvaux.fr" -y tcpip --type auto -e 
AUTOSSH_NTSERVICE=yes


Now, it works great, except if the ssh service at lanvaux.fr would 
become unavailable.

In this case, the service stops.


In the log viewer, I only get the following message in the system log:

The description for Event ID 0 from source AutoSSH cannot be found. 
Either the component that raises this event is not installed on your 
local computer or the installation is corrupted. You can install or 
repair the component on the local computer.

If the event originated on another computer, the display information had 
to be saved with the event.

The following information was included with the event:

AutoSSH: PID 8336: service `AutoSSH' failed: signal 14 raised


and in autoSSH.log:


ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/05/29 10:39:39 autossh[8424]: ssh exited with error status 255; 
restarting ssh
2018/05/29 10:40:29 autossh[8424]: starting ssh (count 12)
2018/05/29 10:40:29 autossh[8424]: ssh child pid is 14616
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/05/29 10:40:50 autossh[8424]: ssh exited with error status 255; 
restarting ssh
2018/05/29 10:42:02 autossh[8424]: starting ssh (count 13)
2018/05/29 10:42:02 autossh[8424]: ssh child pid is 20004
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/05/29 10:42:23 autossh[8424]: ssh exited with error status 255; 
restarting ssh
2018/05/29 10:44:01 autossh[8424]: starting ssh (count 14)
2018/05/29 10:44:01 autossh[8424]: ssh child pid is 3056
ssh: connect to host lanvaux.fr port 22: Connection timed out
2018/05/29 10:44:22 autossh[8424]: ssh exited with error status 255; 
restarting ssh
2018/05/29 16:43:41 autossh[17172]: starting ssh (count 1)

(16:43:41 is when we manually restarted the service.)


 From reading the AutoSSH manpage, I was expecting ssh to always try to 
reconnect (except if it fails on the first try.)

When I noticed the first failure, I tried changing the service settings 
for AutoSSH to restart all the time, but that didn't do it.


Am I missing something regarding AutoSSH configuration?


It is AutoSSH 1.4f



Thank you very much!


Kind regards;

-- 
Germain Le Chapelain
http://lanvaux.fr


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