Re: [CentOS] Centos hold me back from work - sshd ...bull

[Warren Young]

On Apr 28, 2016, at 3:15 AM, John R Pierce  wrote:
> 
> On 4/28/2016 2:09 AM, Andreas Benzler wrote:
>> ine-imac-andy:~ andy$ ssh -vvvandy@141.52.135.21
> 
> 
>> debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 
>> Debian-5ubuntu1.8
>> debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.8 pat OpenSSH_5* compat 
>> 0x0c00
> 
> 
> thats not CentOS.
> 
> are you sure you're connecting to the right address ?

Many of the other answers are ignoring this detail by simply recommending that 
the OP remove the offending line from known_hosts and try again.  That’s an 
excellent way to get MITM’d!

When OpenSSH warns you that the remote host’s key is different from the one it 
saw before, you *must not ignore it* unless you know exactly why it changed.

Don’t guess!  Verify.

How?

Log into the intended host over some trusted channel, then say:

   for f in /etc/ssh/ssh_host_*_key ; do ssh-keygen -lf $f ; done

If none of those values exactly matches

   SHA256:KIKE0V+Hm1UW4XtpTAVsl/7QWqJSVoQHfLnjj3vn/nM.

then OpenSSH is right to prevent your login.  It means you aren’t connecting to 
the server you think you are.  It might be a benign misconfiguration or it 
might be a MITM attempt.

This is potentially a game-over scenario.  Don’t ignore it.

See also this article on the TOFU problem:

 https://en.wikipedia.org/wiki/Trust_on_first_use
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Valeri Galtsev]

On Thu, April 28, 2016 11:25 am, Gordon Messmer wrote:
> On 04/28/2016 02:09 AM, Andreas Benzler wrote:
>> ine-imac-andy:~ andy$ ssh -vvvandy@141.52.135.21
> ...
>> debug1: Enabling compatibility mode for protocol 2.0
>> write: Broken pipe
>> ine-imac-andy:~ andy$ ssh -vvvandy@141.52.135.21
> ...
>> debug1: SSH2_MSG_SERVICE_REQUEST sent
>> ssh_packet_read: Connection reset by peer
>
>
> I see one possibility that explains both the key change and the
> connection resets:
>
> You installed a new server and used an IP address that was already in
> use on another server.  That's why you already had an SSH key for that
> address.  The connection resets occur when the client you're using to
> connect updates its ARP table and swaps from the MAC address on the new
> host to the MAC address on the old host (or visa versa).

Oh yes, and bizarre may happen if you have two machines with the same
static IP _simultaneously_ on the network. To check if that is the case
(for particular IP, say 192.168.2.7) from the machine with different IP on
the same subnet 192.168.2.x do

arping 192.168.2.7

you will get ARP responses from all machines, and if there is more than
one, you will see responces coming from different MAC addresses.

Valeri


Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Gordon Messmer]

On 04/28/2016 02:09 AM, Andreas Benzler wrote:

ine-imac-andy:~ andy$ ssh -vvvandy@141.52.135.21

...

debug1: Enabling compatibility mode for protocol 2.0
write: Broken pipe
ine-imac-andy:~ andy$ ssh -vvvandy@141.52.135.21

...

debug1: SSH2_MSG_SERVICE_REQUEST sent
ssh_packet_read: Connection reset by peer



I see one possibility that explains both the key change and the 
connection resets:


You installed a new server and used an IP address that was already in 
use on another server.  That's why you already had an SSH key for that 
address.  The connection resets occur when the client you're using to 
connect updates its ARP table and swaps from the MAC address on the new 
host to the MAC address on the old host (or visa versa).


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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Valeri Galtsev]

On Thu, April 28, 2016 4:04 am, John R Pierce wrote:
> On 4/28/2016 1:57 AM, Andreas Benzler wrote:
>> the sushi from the laptop always kick me out!!!
>
> huh.   spill chuck gone a rye ?
>

Thank you, John! You made my day!

Valeri

>
> --
> john r pierce, recycling bits in santa cruz
>
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Valeri Galtsev]

On Thu, April 28, 2016 9:25 am, m.r...@5-cent.us wrote:
> Valeri Galtsev wrote:
>>
>> On Thu, April 28, 2016 8:56 am, mdubend...@gmail.com wrote:
>>> The problem is not with your installation of CentOS, it is with the
>>> computer you are connecting from. Read the error log you pasted
>>> earlier,
>>> it tells you exactly what the problem is and how to remedy it:

 Add correct host key in /Users/andy/.ssh/known_hosts to get rid of
 this
 message. Offending ECDSA key in /Users/andy/.ssh/known_hosts:22
>>>
>>> Open up the file /Users/andy/.ssh/known_hosts and delete line 22.
> 
>> Usually host key (of remote machine) could change for the following
>> reasons:
>>
>> 1. benign reasons: remote machine system was reinstalled and/or ssh
>> server
>> keys were re-generated, or some machine was retired and different
>> machine
>> re-used its IP, or for some other reason, like changes in DNS, you are
>> connecting to _different_ system that has same IP as the one you were
>> connecting to in the past
>>
>> In this case it is indeed safe to delete old known keys resembling this
>> host (there may be more that one), then ssh to it and accept new key
>>
>> 2. Bad reasons: remote machine is hijacked and host keys have changed.
>> Or,
>> as ssh error message says, it may be "man in the middle" attack. If some
>> intermediate malicious machine is able to intercept your traffic, it can
> 
> Just as a side note, here: when we rebuild a machine - say, when we were
> doing CentOS 5 to 6, or when we build a new machine for someone, 6->7, we
> *remove /etc/ssh/ssh_host*, and rsync in the *old* /etc/ssh/ssh_host* from
> backup.
>
> Not doing this does have a tendency to freak out the users

Yes that is true. We do this too sometimes, but for machines that are too
long on the network when we upgrade the system we do follow "good security
practice" and re-generate the keys. Even though there is no reason to
think that secret key may be compromised.

Valeri

>
>  mark
>
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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Re: [CentOS] Centos hold me back from work - sshd ...bull

[m . roth]

Valeri Galtsev wrote:
>
> On Thu, April 28, 2016 8:56 am, mdubend...@gmail.com wrote:
>> The problem is not with your installation of CentOS, it is with the
>> computer you are connecting from. Read the error log you pasted earlier,
>> it tells you exactly what the problem is and how to remedy it:
>>>
>>> Add correct host key in /Users/andy/.ssh/known_hosts to get rid of this
>>> message. Offending ECDSA key in /Users/andy/.ssh/known_hosts:22
>>
>> Open up the file /Users/andy/.ssh/known_hosts and delete line 22.

> Usually host key (of remote machine) could change for the following
> reasons:
>
> 1. benign reasons: remote machine system was reinstalled and/or ssh server
> keys were re-generated, or some machine was retired and different machine
> re-used its IP, or for some other reason, like changes in DNS, you are
> connecting to _different_ system that has same IP as the one you were
> connecting to in the past
>
> In this case it is indeed safe to delete old known keys resembling this
> host (there may be more that one), then ssh to it and accept new key
>
> 2. Bad reasons: remote machine is hijacked and host keys have changed. Or,
> as ssh error message says, it may be "man in the middle" attack. If some
> intermediate malicious machine is able to intercept your traffic, it can

Just as a side note, here: when we rebuild a machine - say, when we were
doing CentOS 5 to 6, or when we build a new machine for someone, 6->7, we
*remove /etc/ssh/ssh_host*, and rsync in the *old* /etc/ssh/ssh_host* from
backup.

Not doing this does have a tendency to freak out the users

 mark

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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Andreas Benzler]

I know how todo. I try it out tomorrow. But it’s the first time with this kind 
of problem
with a fresh installed centos 7.

Thanks 
Valeri.

> Am 28.04.2016 um 16:20 schrieb Valeri Galtsev :
> 
> 
> On Thu, April 28, 2016 8:56 am, mdubend...@gmail.com 
>  wrote:
>> The problem is not with your installation of CentOS, it is with the
>> computer you are connecting from. Read the error log you pasted earlier,
>> it
>> tells you exactly what the problem is and how to remedy it:
>> 
>>> 
>>> Add correct host key in /Users/andy/.ssh/known_hosts to get rid of this
>>> message.
>>> Offending ECDSA key in /Users/andy/.ssh/known_hosts:22
>> 
>> 
>> Open up the file /Users/andy/.ssh/known_hosts and delete line 22.
>> 
> 
> (sorry if I repeat what someone already said - it is already long thread,
> and I'm reading my mail from latest messages to oldest...)
> 
> Usually host key (of remote machine) could change for the following reasons:
> 
> 1. benign reasons: remote machine system was reinstalled and/or ssh server
> keys were re-generated, or some machine was retired and different machine
> re-used its IP, or for some other reason, like changes in DNS, you are
> connecting to _different_ system that has same IP as the one you were
> connecting to in the past
> 
> In this case it is indeed safe to delete old known keys resembling this
> host (there may be more that one), then ssh to it and accept new key
> 
> 2. Bad reasons: remote machine is hijacked and host keys have changed. Or,
> as ssh error message says, it may be "man in the middle" attack. If some
> intermediate malicious machine is able to intercept your traffic, it can
> make encrypted ssh tunnel between source machine and itself, and between
> itself and destination machine, having all traffic in clear text on
> itself. The only thing that stops this "man in the middle" is you, as you
> are verifying the host key, and "man in the middle" can not use as host
> key the key of remote machine (he would need both secret and public key of
> the pair for that). This is how ssh is designed to ensure you are talking
> to the machine you think you are talking to.
> 
> If this is the case, you shouldn't continue, instead right thing to do is
> to first make sure that indeed the key of remote machine was changed by
> its admin. Calling remote machine's sysadmin would be right thing to do.
> 
> I hope, this helps.
> 
> Valeri
> 
> 
>> On Thu, Apr 28, 2016 at 2:31 AM, Andreas Benzler 
>> wrote:
>> 
>>> Same machine iMac for the last two weeks.
>>> 
>>> Can work on virtual box  Centos 7
>>> Usb drive installation Centos 7 works
>>> 
>>> Fresh installation not on this laptop.
>>> 
 Am 28.04.2016 um 11:25 schrieb Earl A Ramirez
>>> :
 
 On 28 Apr 2016 11:24, "Andreas Benzler"  wrote:
> 
> sure
>> Am 28.04.2016 um 11:16 schrieb Earl A Ramirez
>>> > 
>> On 28 Apr 2016 11:11, "John R Pierce"  wrote:
>>> 
>>> On 4/28/2016 2:02 AM, Andreas Benzler wrote:
 
 what is wrong with the default sshd server.
 
 after retry to connect sshd - key changed from known hosts
>>> 
>>> 
>>> I've installed centos a LOT of times, versions 5, 6, and 7, and
>>> never
 had
>> any issues with the built in sshd service, and a variety of clients,
>> including other linux ssh, putty and securecrt on windows, gui
>>> SCP/SFTP
>> utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.
>>> 
>>> the "key changed from known_hosts" error happens if your client had
>> previously connected with  the same "user@hostname" on a previous
>> installation of the server OS with a different ssh_host_key
>>> 
>>> 
>>> you need to provide a lot more information if you expect a more
 specific
>> answer from anyone, like what version of CentOS did you install,
>>> what
>> client software you're using to connect to it, any pertinent
>>> background
>> information like was this hostname previously used for a different
>>> OS
>> install, etc etc.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> --
>>> john r pierce, recycling bits in santa cruz
>>> 
>>> ___
>>> CentOS mailing list
>>> CentOS@centos.org
>>> https://lists.centos.org/mailman/listinfo/centos
>> 
>> You installed the server with the same IP, you need to remove the
>>> entry
>> from the known hosts, which is located in .ssh on the computer you
>>> are
>> trying to connect to.
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>> https://lists.centos.org/mailman/listinfo/centos
> 
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> 

Re: [CentOS] Centos hold me back from work - sshd ...bull

[Valeri Galtsev]

On Thu, April 28, 2016 8:56 am, mdubend...@gmail.com wrote:
> The problem is not with your installation of CentOS, it is with the
> computer you are connecting from. Read the error log you pasted earlier,
> it
> tells you exactly what the problem is and how to remedy it:
>
>>
>> Add correct host key in /Users/andy/.ssh/known_hosts to get rid of this
>> message.
>> Offending ECDSA key in /Users/andy/.ssh/known_hosts:22
>
>
> Open up the file /Users/andy/.ssh/known_hosts and delete line 22.
>

(sorry if I repeat what someone already said - it is already long thread,
and I'm reading my mail from latest messages to oldest...)

Usually host key (of remote machine) could change for the following reasons:

1. benign reasons: remote machine system was reinstalled and/or ssh server
keys were re-generated, or some machine was retired and different machine
re-used its IP, or for some other reason, like changes in DNS, you are
connecting to _different_ system that has same IP as the one you were
connecting to in the past

In this case it is indeed safe to delete old known keys resembling this
host (there may be more that one), then ssh to it and accept new key

2. Bad reasons: remote machine is hijacked and host keys have changed. Or,
as ssh error message says, it may be "man in the middle" attack. If some
intermediate malicious machine is able to intercept your traffic, it can
make encrypted ssh tunnel between source machine and itself, and between
itself and destination machine, having all traffic in clear text on
itself. The only thing that stops this "man in the middle" is you, as you
are verifying the host key, and "man in the middle" can not use as host
key the key of remote machine (he would need both secret and public key of
the pair for that). This is how ssh is designed to ensure you are talking
to the machine you think you are talking to.

If this is the case, you shouldn't continue, instead right thing to do is
to first make sure that indeed the key of remote machine was changed by
its admin. Calling remote machine's sysadmin would be right thing to do.

I hope, this helps.

Valeri


> On Thu, Apr 28, 2016 at 2:31 AM, Andreas Benzler 
> wrote:
>
>> Same machine iMac for the last two weeks.
>>
>> Can work on virtual box  Centos 7
>> Usb drive installation Centos 7 works
>>
>> Fresh installation not on this laptop.
>>
>> > Am 28.04.2016 um 11:25 schrieb Earl A Ramirez
>> :
>> >
>> > On 28 Apr 2016 11:24, "Andreas Benzler"  wrote:
>> >>
>> >> sure
>> >>> Am 28.04.2016 um 11:16 schrieb Earl A Ramirez
>> > >:
>> >>>
>> >>> On 28 Apr 2016 11:11, "John R Pierce"  wrote:
>> 
>>  On 4/28/2016 2:02 AM, Andreas Benzler wrote:
>> >
>> > what is wrong with the default sshd server.
>> >
>> > after retry to connect sshd - key changed from known hosts
>> 
>> 
>>  I've installed centos a LOT of times, versions 5, 6, and 7, and
>> never
>> > had
>> >>> any issues with the built in sshd service, and a variety of clients,
>> >>> including other linux ssh, putty and securecrt on windows, gui
>> SCP/SFTP
>> >>> utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.
>> 
>>  the "key changed from known_hosts" error happens if your client had
>> >>> previously connected with  the same "user@hostname" on a previous
>> >>> installation of the server OS with a different ssh_host_key
>> 
>> 
>>  you need to provide a lot more information if you expect a more
>> > specific
>> >>> answer from anyone, like what version of CentOS did you install,
>> what
>> >>> client software you're using to connect to it, any pertinent
>> background
>> >>> information like was this hostname previously used for a different
>> OS
>> >>> install, etc etc.
>> 
>> 
>> 
>> 
>> 
>> 
>>  --
>>  john r pierce, recycling bits in santa cruz
>> 
>>  ___
>>  CentOS mailing list
>>  CentOS@centos.org
>>  https://lists.centos.org/mailman/listinfo/centos
>> >>>
>> >>> You installed the server with the same IP, you need to remove the
>> entry
>> >>> from the known hosts, which is located in .ssh on the computer you
>> are
>> >>> trying to connect to.
>> >>> ___
>> >>> CentOS mailing list
>> >>> CentOS@centos.org
>> >>> https://lists.centos.org/mailman/listinfo/centos
>> >>
>> >> ___
>> >> CentOS mailing list
>> >> CentOS@centos.org
>> >> https://lists.centos.org/mailman/listinfo/centos
>> >
>> > I meant the computer you are trying to connect from.
>> > ___
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>> > CentOS@centos.org
>> > https://lists.centos.org/mailman/listinfo/centos
>>
>> ___
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>> 

Re: [CentOS] Centos hold me back from work - sshd ...bull

[mdubend...@gmail.com]

The problem is not with your installation of CentOS, it is with the
computer you are connecting from. Read the error log you pasted earlier, it
tells you exactly what the problem is and how to remedy it:

>
> Add correct host key in /Users/andy/.ssh/known_hosts to get rid of this
> message.
> Offending ECDSA key in /Users/andy/.ssh/known_hosts:22


Open up the file /Users/andy/.ssh/known_hosts and delete line 22.

On Thu, Apr 28, 2016 at 2:31 AM, Andreas Benzler 
wrote:

> Same machine iMac for the last two weeks.
>
> Can work on virtual box  Centos 7
> Usb drive installation Centos 7 works
>
> Fresh installation not on this laptop.
>
> > Am 28.04.2016 um 11:25 schrieb Earl A Ramirez :
> >
> > On 28 Apr 2016 11:24, "Andreas Benzler"  wrote:
> >>
> >> sure
> >>> Am 28.04.2016 um 11:16 schrieb Earl A Ramirez  >:
> >>>
> >>> On 28 Apr 2016 11:11, "John R Pierce"  wrote:
> 
>  On 4/28/2016 2:02 AM, Andreas Benzler wrote:
> >
> > what is wrong with the default sshd server.
> >
> > after retry to connect sshd - key changed from known hosts
> 
> 
>  I've installed centos a LOT of times, versions 5, 6, and 7, and never
> > had
> >>> any issues with the built in sshd service, and a variety of clients,
> >>> including other linux ssh, putty and securecrt on windows, gui SCP/SFTP
> >>> utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.
> 
>  the "key changed from known_hosts" error happens if your client had
> >>> previously connected with  the same "user@hostname" on a previous
> >>> installation of the server OS with a different ssh_host_key
> 
> 
>  you need to provide a lot more information if you expect a more
> > specific
> >>> answer from anyone, like what version of CentOS did you install, what
> >>> client software you're using to connect to it, any pertinent background
> >>> information like was this hostname previously used for a different OS
> >>> install, etc etc.
> 
> 
> 
> 
> 
> 
>  --
>  john r pierce, recycling bits in santa cruz
> 
>  ___
>  CentOS mailing list
>  CentOS@centos.org
>  https://lists.centos.org/mailman/listinfo/centos
> >>>
> >>> You installed the server with the same IP, you need to remove the entry
> >>> from the known hosts, which is located in .ssh on the computer you are
> >>> trying to connect to.
> >>> ___
> >>> CentOS mailing list
> >>> CentOS@centos.org
> >>> https://lists.centos.org/mailman/listinfo/centos
> >>
> >> ___
> >> CentOS mailing list
> >> CentOS@centos.org
> >> https://lists.centos.org/mailman/listinfo/centos
> >
> > I meant the computer you are trying to connect from.
> > ___
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> > CentOS@centos.org
> > https://lists.centos.org/mailman/listinfo/centos
>
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Andreas Benzler]

Same machine iMac for the last two weeks.

Can work on virtual box  Centos 7
Usb drive installation Centos 7 works

Fresh installation not on this laptop.

> Am 28.04.2016 um 11:25 schrieb Earl A Ramirez :
> 
> On 28 Apr 2016 11:24, "Andreas Benzler"  wrote:
>> 
>> sure
>>> Am 28.04.2016 um 11:16 schrieb Earl A Ramirez :
>>> 
>>> On 28 Apr 2016 11:11, "John R Pierce"  wrote:
 
 On 4/28/2016 2:02 AM, Andreas Benzler wrote:
> 
> what is wrong with the default sshd server.
> 
> after retry to connect sshd - key changed from known hosts
 
 
 I've installed centos a LOT of times, versions 5, 6, and 7, and never
> had
>>> any issues with the built in sshd service, and a variety of clients,
>>> including other linux ssh, putty and securecrt on windows, gui SCP/SFTP
>>> utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.
 
 the "key changed from known_hosts" error happens if your client had
>>> previously connected with  the same "user@hostname" on a previous
>>> installation of the server OS with a different ssh_host_key
 
 
 you need to provide a lot more information if you expect a more
> specific
>>> answer from anyone, like what version of CentOS did you install, what
>>> client software you're using to connect to it, any pertinent background
>>> information like was this hostname previously used for a different OS
>>> install, etc etc.
 
 
 
 
 
 
 --
 john r pierce, recycling bits in santa cruz
 
 ___
 CentOS mailing list
 CentOS@centos.org
 https://lists.centos.org/mailman/listinfo/centos
>>> 
>>> You installed the server with the same IP, you need to remove the entry
>>> from the known hosts, which is located in .ssh on the computer you are
>>> trying to connect to.
>>> ___
>>> CentOS mailing list
>>> CentOS@centos.org
>>> https://lists.centos.org/mailman/listinfo/centos
>> 
>> ___
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>> CentOS@centos.org
>> https://lists.centos.org/mailman/listinfo/centos
> 
> I meant the computer you are trying to connect from.
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Earl A Ramirez]

On 28 Apr 2016 11:24, "Andreas Benzler"  wrote:
>
> sure
> > Am 28.04.2016 um 11:16 schrieb Earl A Ramirez :
> >
> > On 28 Apr 2016 11:11, "John R Pierce"  wrote:
> >>
> >> On 4/28/2016 2:02 AM, Andreas Benzler wrote:
> >>>
> >>> what is wrong with the default sshd server.
> >>>
> >>> after retry to connect sshd - key changed from known hosts
> >>
> >>
> >> I've installed centos a LOT of times, versions 5, 6, and 7, and never
had
> > any issues with the built in sshd service, and a variety of clients,
> > including other linux ssh, putty and securecrt on windows, gui SCP/SFTP
> > utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.
> >>
> >> the "key changed from known_hosts" error happens if your client had
> > previously connected with  the same "user@hostname" on a previous
> > installation of the server OS with a different ssh_host_key
> >>
> >>
> >> you need to provide a lot more information if you expect a more
specific
> > answer from anyone, like what version of CentOS did you install, what
> > client software you're using to connect to it, any pertinent background
> > information like was this hostname previously used for a different OS
> > install, etc etc.
> >>
> >>
> >>
> >>
> >>
> >>
> >> --
> >> john r pierce, recycling bits in santa cruz
> >>
> >> ___
> >> CentOS mailing list
> >> CentOS@centos.org
> >> https://lists.centos.org/mailman/listinfo/centos
> >
> > You installed the server with the same IP, you need to remove the entry
> > from the known hosts, which is located in .ssh on the computer you are
> > trying to connect to.
> > ___
> > CentOS mailing list
> > CentOS@centos.org
> > https://lists.centos.org/mailman/listinfo/centos
>
> ___
> CentOS mailing list
> CentOS@centos.org
> https://lists.centos.org/mailman/listinfo/centos

I meant the computer you are trying to connect from.
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Andreas Benzler]

sure
> Am 28.04.2016 um 11:16 schrieb Earl A Ramirez :
> 
> On 28 Apr 2016 11:11, "John R Pierce"  wrote:
>> 
>> On 4/28/2016 2:02 AM, Andreas Benzler wrote:
>>> 
>>> what is wrong with the default sshd server.
>>> 
>>> after retry to connect sshd - key changed from known hosts
>> 
>> 
>> I've installed centos a LOT of times, versions 5, 6, and 7, and never had
> any issues with the built in sshd service, and a variety of clients,
> including other linux ssh, putty and securecrt on windows, gui SCP/SFTP
> utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.
>> 
>> the "key changed from known_hosts" error happens if your client had
> previously connected with  the same "user@hostname" on a previous
> installation of the server OS with a different ssh_host_key
>> 
>> 
>> you need to provide a lot more information if you expect a more specific
> answer from anyone, like what version of CentOS did you install, what
> client software you're using to connect to it, any pertinent background
> information like was this hostname previously used for a different OS
> install, etc etc.
>> 
>> 
>> 
>> 
>> 
>> 
>> --
>> john r pierce, recycling bits in santa cruz
>> 
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> 
> You installed the server with the same IP, you need to remove the entry
> from the known hosts, which is located in .ssh on the computer you are
> trying to connect to.
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Earl A Ramirez]

On 28 Apr 2016 11:11, "John R Pierce"  wrote:
>
> On 4/28/2016 2:02 AM, Andreas Benzler wrote:
>>
>> what is wrong with the default sshd server.
>>
>> after retry to connect sshd - key changed from known hosts
>
>
> I've installed centos a LOT of times, versions 5, 6, and 7, and never had
any issues with the built in sshd service, and a variety of clients,
including other linux ssh, putty and securecrt on windows, gui SCP/SFTP
utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.
>
> the "key changed from known_hosts" error happens if your client had
previously connected with  the same "user@hostname" on a previous
installation of the server OS with a different ssh_host_key
>
>
> you need to provide a lot more information if you expect a more specific
answer from anyone, like what version of CentOS did you install, what
client software you're using to connect to it, any pertinent background
information like was this hostname previously used for a different OS
install, etc etc.
>
>
>
>
>
>
> --
> john r pierce, recycling bits in santa cruz
>
> ___
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You installed the server with the same IP, you need to remove the entry
from the known hosts, which is located in .ssh on the computer you are
trying to connect to.
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[John R Pierce]

On 4/28/2016 2:09 AM, Andreas Benzler wrote:

ine-imac-andy:~ andy$ ssh -vvvandy@141.52.135.21




debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 
Debian-5ubuntu1.8
debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.8 pat OpenSSH_5* compat 0x0c00



thats not CentOS.

are you sure you're connecting to the right address ?

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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Andreas Benzler]

This never happen to  me,  first time too. This was never happen when i drive 
the machine with the usb drive installation of centos, same state.
As I said: Fresh from yesterday.

Greetings

Andy

> Am 28.04.2016 um 11:11 schrieb John R Pierce :
> 
> On 4/28/2016 2:02 AM, Andreas Benzler wrote:
>> what is wrong with the default sshd server.
>> 
>> after retry to connect sshd - key changed from known hosts
> 
> I've installed centos a LOT of times, versions 5, 6, and 7, and never had any 
> issues with the built in sshd service, and a variety of clients, including 
> other linux ssh, putty and securecrt on windows, gui SCP/SFTP utilties(they 
> use sshd too), freebsd ssh, solaris ssh, aix ssh.
> 
> the "key changed from known_hosts" error happens if your client had 
> previously connected with  the same "user@hostname" on a previous 
> installation of the server OS with a different ssh_host_key
> 
> 
> you need to provide a lot more information if you expect a more specific 
> answer from anyone, like what version of CentOS did you install, what client 
> software you're using to connect to it, any pertinent background information 
> like was this hostname previously used for a different OS install, etc etc.
> 
> 
> 
> 
> 
> -- 
> john r pierce, recycling bits in santa cruz
> 
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[John R Pierce]

On 4/28/2016 2:02 AM, Andreas Benzler wrote:

what is wrong with the default sshd server.

after retry to connect sshd - key changed from known hosts


I've installed centos a LOT of times, versions 5, 6, and 7, and never 
had any issues with the built in sshd service, and a variety of clients, 
including other linux ssh, putty and securecrt on windows, gui SCP/SFTP 
utilties(they use sshd too), freebsd ssh, solaris ssh, aix ssh.


the "key changed from known_hosts" error happens if your client had 
previously connected with  the same "user@hostname" on a previous 
installation of the server OS with a different ssh_host_key



you need to provide a lot more information if you expect a more specific 
answer from anyone, like what version of CentOS did you install, what 
client software you're using to connect to it, any pertinent background 
information like was this hostname previously used for a different OS 
install, etc etc.






--
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Andreas Benzler]

ine-imac-andy:~ andy$ ssh 141.52.135.21
@@@
@WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
SHA256:KIKE0V+Hm1UW4XtpTAVsl/7QWqJSVoQHfLnjj3vn/nM.
Please contact your system administrator.
Add correct host key in /Users/andy/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/andy/.ssh/known_hosts:22
RSA host key for 141.52.135.21 has changed and you have requested strict 
checking.
Host key verification failed.
ine-imac-andy:~ andy$ vi .ssh/
id_rsa   id_rsa.pub   known_hosts  
ine-imac-andy:~ andy$ vi .ssh/known_hosts 
ine-imac-andy:~ andy$ ssh -vvv andy@141.52.135.21
OpenSSH_6.9p1, LibreSSL 2.1.8
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: /etc/ssh/ssh_config line 56: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 141.52.135.21 [141.52.135.21] port 22.
debug1: Connection established.
debug1: identity file /Users/andy/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
write: Broken pipe
ine-imac-andy:~ andy$ ssh -vvv andy@141.52.135.21
OpenSSH_6.9p1, LibreSSL 2.1.8
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: /etc/ssh/ssh_config line 56: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 141.52.135.21 [141.52.135.21] port 22.
debug1: Connection established.
debug1: identity file /Users/andy/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/andy/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.9
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 
Debian-5ubuntu1.8
debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.8 pat OpenSSH_5* compat 0x0c00
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 141.52.135.21:22 as 'andy'
debug3: hostkeys_foreach: reading file "/Users/andy/.ssh/known_hosts"
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: 
curve25519-sha...@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: 
ecdsa-sha2-nistp256-cert-...@openssh.com,ecdsa-sha2-nistp384-cert-...@openssh.com,ecdsa-sha2-nistp521-cert-...@openssh.com,ssh-ed25519-cert-...@openssh.com,ssh-rsa-cert-...@openssh.com,ssh-dss-cert-...@openssh.com,ssh-rsa-cert-...@openssh.com,ssh-dss-cert-...@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: 
chacha20-poly1...@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-...@openssh.com,aes256-...@openssh.com,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-...@lysator.liu.se
debug2: kex_parse_kexinit: 

Re: [CentOS] Centos hold me back from work - sshd ...bull

[Earl A Ramirez]

On 28 Apr 2016 10:58, "Andreas Benzler"  wrote:
>
> I don’t know what’s going on
>
> the sushi from the laptop always kick me out!!!
>
> Fresh installation.
>
> packet_write_wait: Connection
>
> How can that be!
>
> Andy
>
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You will need to provide a little more information, what's the output when
you use ssh -vvv user@host?
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Re: [CentOS] Centos hold me back from work - sshd ...bull

[John R Pierce]

On 4/28/2016 1:57 AM, Andreas Benzler wrote:

the sushi from the laptop always kick me out!!!


huh.   spill chuck gone a rye ?


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Re: [CentOS] Centos hold me back from work - sshd ...bull

[Andreas Benzler]

what is wrong with the default sshd server.

after retry to connect sshd - key changed from known hosts

grrr

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[CentOS] Centos hold me back from work - sshd ...bull

[Andreas Benzler]

I don’t know what’s going on

the sushi from the laptop always kick me out!!!

Fresh installation.

packet_write_wait: Connection

How can that be!

Andy

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