** Description changed:
python3-paramiko can't connect to Jammy hosts, likely because of the
stricter signature requirements introduced in openssh 8.8p1-1.
Reproducer:
- 1. Setup a passwordless keypair and add localhost to known_hosts, so
- that:
+ 1. Setup a passwordless keypair and add localhost to known_hosts:
+
+ $ sudo apt install -y openssh-server openssh-client ipython3 python3-paramiko
+ $ ssh-keygen -f ~/.ssh/id_rsa_insecure
+ $ SSH_AUTH_SOCK= ssh-copy-id -i ~/.ssh/id_rsa_insecure localhost
+
+ 2. Verify setup:
paride@stramonio:~$ SSH_AUTH_SOCK= ssh -i ~/.ssh/id_rsa_insecure localhost
date
2022-02-23T12:35:39 CET
- 2. Try the same with paramiko from python3-paramiko:
+ 3. Try the same with paramiko from python3-paramiko:
$ ipython3
- In [1]: from paramiko import SSHClient
- In [2]: client = SSHClient()
+ In [1]: import paramiko, os
+ In [2]: client = paramiko.SSHClient()
In [3]: client.load_system_host_keys()
- In [4]: client.connect('localhost',
key_filename='/home/paride/.ssh/id_rsa_insecure')
+ In [4]: client.connect('localhost',
key_filename=os.path.expanduser('~/.ssh/id_rsa_insecure'))
Unknown exception: q must be exactly 160, 224, or 256 bits long
[Full Traceback Below]
- 3. Try with a newer paramiko:
+ 4. Try with a newer paramiko:
$ python3 -m venv /tmp/newparamiko
$ source /tmp/newparamiko/bin/activate
$ pip install -q paramiko==2.9.2
$ ipython3
- In [1]: from paramiko import SSHClient
- In [2]: client = SSHClient()
+ In [1]: import paramiko, os
+ In [2]: client = paramiko.SSHClient()
In [3]: client.load_system_host_keys()
- In [4]: client.connect('localhost',
key_filename='/home/paride/.ssh/id_rsa_insecure')
+ In [4]: client.connect('localhost',
key_filename=os.path.expanduser('~/.ssh/id_rsa_insecure'))
In [5]: # It works!
- The Point 2. failure can be reproduced by installing older versions of
+ The Point 3. failure can be reproduced by installing older versions of
paramiko via pip, so the issue is not specific to Ubuntu. Likely related
upstream changes/issues:
* https://github.com/paramiko/paramiko/pull/1643
* https://github.com/paramiko/paramiko/issues/1955
- --- Point 2. Traceback ---
+ --- Point 3. Traceback ---
Traceback (most recent call last):
- File "/usr/lib/python3/dist-packages/paramiko/transport.py", line 2109, in
run
- handler(self.auth_handler, m)
- File "/usr/lib/python3/dist-packages/paramiko/auth_handler.py", line 298,
in _parse_service_accept
- sig = self.private_key.sign_ssh_data(blob)
- File "/usr/lib/python3/dist-packages/paramiko/dsskey.py", line 109, in
sign_ssh_data
- key = dsa.DSAPrivateNumbers(
- File
"/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/asymmetric/dsa.py",
line 244, in private_key
- return backend.load_dsa_private_numbers(self)
- File
"/usr/lib/python3/dist-packages/cryptography/hazmat/backends/openssl/backend.py",
line 827, in load_dsa_private_numbers
- dsa._check_dsa_private_numbers(numbers)
- File
"/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/asymmetric/dsa.py",
line 282, in _check_dsa_private_numbers
- _check_dsa_parameters(parameters)
- File
"/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/asymmetric/dsa.py",
line 274, in _check_dsa_parameters
- raise ValueError("q must be exactly 160, 224, or 256 bits long")
+ File "/usr/lib/python3/dist-packages/paramiko/transport.py", line 2109, in
run
+ handler(self.auth_handler, m)
+ File "/usr/lib/python3/dist-packages/paramiko/auth_handler.py", line 298,
in _parse_service_accept
+ sig = self.private_key.sign_ssh_data(blob)
+ File "/usr/lib/python3/dist-packages/paramiko/dsskey.py", line 109, in
sign_ssh_data
+ key = dsa.DSAPrivateNumbers(
+ File
"/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/asymmetric/dsa.py",
line 244, in private_key
+ return backend.load_dsa_private_numbers(self)
+ File
"/usr/lib/python3/dist-packages/cryptography/hazmat/backends/openssl/backend.py",
line 827, in load_dsa_private_numbers
+ dsa._check_dsa_private_numbers(numbers)
+ File
"/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/asymmetric/dsa.py",
line 282, in _check_dsa_private_numbers
+ _check_dsa_parameters(parameters)
+ File
"/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/asymmetric/dsa.py",
line 274, 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
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https://bugs.launchpad.net/bugs/1961979
Title:
Can't connect to Jammy hosts (openssh >= 8.8p1-1)
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