SSH connection from Linux to Windows by CYGSSHD: port 22

SSH connection from Linux to Windows by CYGSSHD: port 22

[Greco Giovanni]

Hello,
must port 22 on Windows server be enabled in a bidirectional way to establish a connection with RSA key exchange?
I have a Linux server on a vlan and a Windows server on another vlan, those vlans are connected thru a firewall, where port 22 is enabled from Linux server to Windows server unidirectionally.
Connection with user and password works, but not with RSA key exchange: is the problem located on port 22 unidirectional enabling?
Thanks in advance.
Giovanni Greco - BlueIT S.p.A.

Re: SSH connection from Linux to Windows by CYGSSHD: port 22

[Andrey Repin]

Greetings, Greco Giovanni!

> must port 22 on Windows server be enabled in a bidirectional way to
> establish a connection with RSA key exchange?
> I have a Linux server on a vlan and a Windows server on another vlan, those
> vlans are connected thru a firewall, where port 22 is enabled from Linux
> server to Windows server unidirectionally.
> Connection with user and password works, but not with RSA key exchange: is
> the problem located on port 22 unidirectional enabling?

No, it is most likely because you are connecting to Microsoft provided
OpenSSH.
`netstat -aon` and `ps ax` will tell you more.


-- 
With best regards,
Andrey Repin
Thursday, March 31, 2022 16:16:07

Sorry for my terrible english...

Re: SSH connection from Linux to Windows by CYGSSHD: port 22

[Chris Roehrig]

I recently had to add the following lines to my Cygwin /etc/sshd_config 
to re-enable RSA in order for my older machines to connect:

HostKeyAlgorithms +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa


-- Chris

On 2022-03-31 06:18, Andrey Repin wrote:
> Greetings, Greco Giovanni!
>
>> must port 22 on Windows server be enabled in a bidirectional way to
>> establish a connection with RSA key exchange?
>> I have a Linux server on a vlan and a Windows server on another vlan, those
>> vlans are connected thru a firewall, where port 22 is enabled from Linux
>> server to Windows server unidirectionally.
>> Connection with user and password works, but not with RSA key exchange: is
>> the problem located on port 22 unidirectional enabling?
> No, it is most likely because you are connecting to Microsoft provided
> OpenSSH.
> `netstat -aon` and `ps ax` will tell you more.
>
>

Re: SSH connection from Linux to Windows by CYGSSHD: port 22

[Andrey Repin]

Greetings, Chris Roehrig!

> I recently had to add the following lines to my Cygwin /etc/sshd_config to
> re-enable RSA in order for my older machines to connect:

> HostKeyAlgorithms +ssh-rsa
> PubkeyAcceptedAlgorithms +ssh-rsa

I'm not using RSA for, like, 5 years now.
Too long to manage.

> -- Chris

> On 2022-03-31 06:18, Andrey Repin wrote:
>> Greetings, Greco Giovanni!
>>
>>> must port 22 on Windows server be enabled in a bidirectional way to
>>> establish a connection with RSA key exchange?
>>> I have a Linux server on a vlan and a Windows server on another vlan, those
>>> vlans are connected thru a firewall, where port 22 is enabled from Linux
>>> server to Windows server unidirectionally.
>>> Connection with user and password works, but not with RSA key exchange: is
>>> the problem located on port 22 unidirectional enabling?
>> No, it is most likely because you are connecting to Microsoft provided
>> OpenSSH.
>> `netstat -aon` and `ps ax` will tell you more.
>>
>>




-- 
With best regards,
Andrey Repin
Thursday, March 31, 2022 23:03:27

Sorry for my terrible english...