Unknown exception: q must be exactly 160, 224, or 256 bits long

Due diligence #2140 appers to result in the same behavior

Describe the bug Attempting an SSH connection results in the following error: Unknown exception: q must be exactly 160, 224, or 256 bits long

To Reproduce Just run a pythonfile containing the code below. Right now, the private key is not encrypted and the config file in .ssh is empty.

Expected behaviour Successful SSH connection to the server

Environment

• What version of the Python interpreter are you using? 3.7.10
• What operating system are you using both client & server-side? Windows10 & Ubuntu
• Are you using OpenSSH server or something else? OpenSSH (Windows10 default)
• Which version or versions of the software are you using? fabric 2.6.0
  • Have you, or can you, try some older releases to pin down where the bug appeared? Not tried yet
• How can the developers recreate the bug on their end? If possible, include a copy of your code, the command you used to invoke it, and the full output of your run (if applicable.)

from fabric import Connection

c = Connection(host='<IP>', user='<USER>', connect_kwargs={"key_filename": "C:\\Users\\<user>\\.ssh\\id_rsa"})
c.run('ls')

Output

Unknown exception: q must be exactly 160, 224, or 256 bits long
Traceback (most recent call last):
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\transport.py", line 2109, in run
    handler(self.auth_handler, m)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\auth_handler.py", line 298, in _parse_service_accept
    sig = self.private_key.sign_ssh_data(blob)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\dsskey.py", line 116, in sign_ssh_data
    ).private_key(backend=default_backend())
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\primitives\asymmetric\dsa.py", line 243, in private_key
    return backend.load_dsa_private_numbers(self)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\backends\openssl\backend.py", line 657, in load_dsa_private_numbers
    dsa._check_dsa_private_numbers(numbers)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\primitives\asymmetric\dsa.py", line 142, in _check_dsa_private_numbers
    _check_dsa_parameters(parameters)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\primitives\asymmetric\dsa.py", line 134, in _check_dsa_parameters
    raise ValueError("q must be exactly 160, 224, or 256 bits long")
ValueError: q must be exactly 160, 224, or 256 bits long

Traceback (most recent call last):
  File ".\target_setup.py", line 4, in <module>
    c.run('ls')
  File "<decorator-gen-3>", line 2, in run
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\fabric\connection.py", line 29, in opens
    self.open()
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\fabric\connection.py", line 636, in open
    self.client.connect(**kwargs)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\client.py", line 446, in connect
    passphrase,
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\client.py", line 680, in _auth
    self._transport.auth_publickey(username, key)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\transport.py", line 1580, in auth_publickey
    return self.auth_handler.wait_for_response(my_event)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\auth_handler.py", line 236, in wait_for_response
    raise e
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\transport.py", line 2109, in run
    handler(self.auth_handler, m)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\auth_handler.py", line 298, in _parse_service_accept
    sig = self.private_key.sign_ssh_data(blob)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\paramiko\dsskey.py", line 116, in sign_ssh_data
    ).private_key(backend=default_backend())
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\primitives\asymmetric\dsa.py", line 243, in private_key
    return backend.load_dsa_private_numbers(self)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\backends\openssl\backend.py", line 657, in load_dsa_private_numbers
    dsa._check_dsa_private_numbers(numbers)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\primitives\asymmetric\dsa.py", line 142, in _check_dsa_private_numbers
    _check_dsa_parameters(parameters)
  File "C:\Users\mle\AppData\Local\Continuum\anaconda3\envs\blackthorn\lib\site-packages\cryptography\hazmat\primitives\asymmetric\dsa.py", line 134, in _check_dsa_parameters
    raise ValueError("q must be exactly 160, 224, or 256 bits long")
ValueError: q must be exactly 160, 224, or 256 bits long

Additional context Add any other context about the problem here.

[suhassumukh]

I, too, encountered the exact same error. It turned out that I was supplying a username that did not exist on the target machine. The error went away after I corrected my mistake.

Fabric 1.10.2

[herve-guerin-pro]

Hi, I have the same issue when I use paramiko==2.11.0 or paramiko==2.10.1 and I don’t have the issue if I use paramiko=2.8.1 It seems that PR #1606 addressed this issue successfully : is there any reason for not fixing that in the recent releases of paramiko ?