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Old 09-14-2012, 03:32 PM
Scott Silva
 
Default ssh_exchange_identification: Connection closed by remote host

on 9/14/2012 8:26 AM m.roth@5-cent.us spake the
following:
> M. Fioretti wrote:
>>
>> I have accounts on two Centos servers, A and B, each hosted on a remote
>> VPS by a different provider/datacenter.
>>
>> Until yesterday night, I could connect without problems via SSH to both
>> servers from my home Fedora 16 desktop.
>>
>> Yesterday I completed (fingers crossed) the switch to a different ADSL
>> provider. From the moment I turned on the modem on the new ADSL line, I
>> became unable to ssh into server A. All attempts abort with this message:
>>
>> ssh_exchange_identification: Connection closed by remote host
> <snip>
> This would be obnoxious, but have you checked with your ADSL provider, to
> see if they're blocking ssh traffic?
>
> mark
>
Also. Could the server A have a firewall that had allow ranges for your
original ip range? Or denyhosts... something like that

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Old 09-14-2012, 03:44 PM
Tony Molloy
 
Default ssh_exchange_identification: Connection closed by remote host

On Friday 14 September 2012 16:32:18 Scott Silva wrote:
> on 9/14/2012 8:26 AM m.roth@5-cent.us spake the
>
> following:
> > M. Fioretti wrote:
> >> I have accounts on two Centos servers, A and B, each hosted on a
> >> remote VPS by a different provider/datacenter.
> >>
> >> Until yesterday night, I could connect without problems via SSH
> >> to both servers from my home Fedora 16 desktop.
> >>
> >> Yesterday I completed (fingers crossed) the switch to a
> >> different ADSL provider. From the moment I turned on the modem
> >> on the new ADSL line, I became unable to ssh into server A. All
> >> attempts abort with this message:
> >>
> >> ssh_exchange_identification: Connection closed by remote host
> >
> > <snip>
> > This would be obnoxious, but have you checked with your ADSL
> > provider, to see if they're blocking ssh traffic?
> >
> > mark
>
> Also. Could the server A have a firewall that had allow ranges for
> your original ip range? Or denyhosts... something like that

>From memory the only time I've seen that error message was due to
entries in the /etc/hosts.allow file specifying what IP addresses are
allowed ssh in. Changing your ISP would change your address.

Tony
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
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Old 09-14-2012, 04:09 PM
Leon Fauster
 
Default ssh_exchange_identification: Connection closed by remote host

Am 14.09.2012 um 17:09 schrieb M. Fioretti:
> Greetings,
>
> I have accounts on two Centos servers, A and B, each hosted on a remote
> VPS by a different provider/datacenter.
>
> Until yesterday night, I could connect without problems via SSH to both
> servers from my home Fedora 16 desktop.
>
> Yesterday I completed (fingers crossed) the switch to a different ADSL
> provider. From the moment I turned on the modem on the new ADSL line, I
> became unable to ssh into server A. All attempts abort with this message:
>
> ssh_exchange_identification: Connection closed by remote host



Check your tcp_wrapper configuration (/etc/hosts.allow, /etc/hosts.deny).

--
LF




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Old 09-14-2012, 07:06 PM
 
Default ssh_exchange_identification: Connection closed by remote host

>> On Fri, 14 Sep 2012 17:09:46 +0200 (CEST),
>> "M. Fioretti" <mfioretti@nexaima.net> said:

M> Yesterday I completed (fingers crossed) the switch to a different ADSL
M> provider. From the moment I turned on the modem on the new ADSL line, I
M> became unable to ssh into server A. All attempts abort with this
M> message:
M> ssh_exchange_identification: Connection closed by remote host

This is in the "grasping at straws" category, but have you tried
connecting with a different cipher, like "blowfish" or "3des-cbc"?

If/as/when you get access to the server, can you disable TCP checksum
offloading?

root# ethtool -K eth0 tx off rx off
root# ethtool -t eth0 offline # adapter self-test

--
Karl Vogel I don't speak for the USAF or my company
A sum of accountants --collective nouns, June 1999 LINGUIST
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Old 09-14-2012, 09:48 PM
Stephen Harris
 
Default ssh_exchange_identification: Connection closed by remote host

On Fri, Sep 14, 2012 at 10:21:29PM +0200, M. Fioretti wrote:
> No, it's not, sorry for the confusion. I meant to write "as soon as the
> server is reachable again"

I haven't seen lower level debugging, but I may have just missed it.

1) What happens if you run "telnet yourhost 22".
(you might need to install "telnet" on your client machine)
Do you see something like
Trying 1.2.3.4...
Connected to yourhost (1.2.3.4)
Escape character is '^]'.
SSH-2.0-OpenSSH_5.3
or do you see
telnet: Unable to connect to remote host: Connection refused
or do you see
Trying 1.2.3.4...
Connected to yourhost (1.2.3.4)
Escape character is '^]'.
Connection closed by foreign host.

2) How quickly does the "closed" occur?

3) What is the output of "ssh -v yourhost"

?

--

rgds
Stephen
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Old 09-14-2012, 10:10 PM
Ken Smith
 
Default ssh_exchange_identification: Connection closed by remote host

Stephen Harris wrote:
> On Fri, Sep 14, 2012 at 10:21:29PM +0200, M. Fioretti wrote:
>
>> No, it's not, sorry for the confusion. I meant to write "as soon as the
>> server is reachable again"
>>
> {snip}
>
> ?
>
>
Can you ssh from B to A?

:-) Ken

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Old 09-15-2012, 02:00 AM
Paul Tader
 
Default ssh_exchange_identification: Connection closed by remote host

On Sep 14, 2012, at 3:21 PM, "M. Fioretti" <mfioretti@nexaima.net> wrote:

>
> On Fri, September 14, 2012 10:09 pm, m.roth@5-cent.us wrote:
>
>>> I'll try that as the server is reachable again.
>>
>> It's now reachable?
>
> No, it's not, sorry for the confusion. I meant to write "as soon as the
> server is reachable again"
>
> Marco
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Can you post the (sanitized ) output from "ssh -vv my mybadhost.com" ?
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Old 09-15-2012, 05:02 AM
"M. Fioretti"
 
Default ssh_exchange_identification: Connection closed by remote host

On Sat, September 15, 2012 12:10 am, Ken Smith wrote:
> Stephen Harris wrote:
>> On Fri, Sep 14, 2012 at 10:21:29PM +0200, M. Fioretti wrote:
>>
>>> No, it's not, sorry for the confusion. I meant to write "as soon as the
>>> server is reachable again"
>>
> Can you ssh from B to A?

very good question, thanks! I had not thought about such a test at all.
However, doing that I get exactly the same result.

Marco
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Old 09-15-2012, 05:44 AM
Ken Smith
 
Default ssh_exchange_identification: Connection closed by remote host

M. Fioretti wrote:
> On Sat, September 15, 2012 12:10 am, Ken Smith wrote:
>
>> Stephen Harris wrote:
>>
>>> On Fri, Sep 14, 2012 at 10:21:29PM +0200, M. Fioretti wrote:
>>>
>>>
>>> {snip}
>> Can you ssh from B to A?
>>
> very good question, thanks! I had not thought about such a test at all.
> However, doing that I get exactly the same result.
>
> Marco
>
>
Which suggests that there is something about A you need to know more
about. As said earlier what happens if you run

telnet ip-of-a whatever-port-ssh-is -on--normally-22

:-) Ken

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Old 09-15-2012, 07:00 AM
"M. Fioretti"
 
Default ssh_exchange_identification: Connection closed by remote host

On Sat, September 15, 2012 7:44 am, Ken Smith wrote:

> Which suggests that there is something about A you need to know more
> about. As said earlier what happens if you run
>
> telnet ip-of-a whatever-port-ssh-is -on--normally-22

I had already answered to this:

http://lists.centos.org/pipermail/centos/2012-September/129092.html

If I use port 22 instead of the one sshd is listening on, I get a normal
"telnet: connect to address ip-of-a: Connection refused"

Marco

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