Need to add disabled algorithms support to Netmiko

[ktbyers]

See:

paramiko/paramiko#1961

[ktbyers]

-        ssh.connect(ip, username=username, pkey=ssh_key, timeout=3)
+        ssh.connect(ip, username=username, pkey=ssh_key, timeout=3, disabled_algorithms=dict(pubkeys=['rsa-sha2-256', 'rsa-sha2-512']))

[ktbyers]

User ran into this where username/password auth would work, but key-auth would fail:

DEBUG:paramiko.transport:Our pubkey algorithm list: ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-rsa']
DEBUG:paramiko.transport:Server did not send a server-sig-algs list; defaulting to our first preferred algo ('rsa-sha2-512')
DEBUG:paramiko.transport:NOTE: you may use the 'disabled_algorithms' SSHClient/Transport init kwarg to disable that or other algorithms if your server does not support them!

Downgrading to Paramiko 2.8.1 fixed the issue.

[jonglezb]

Proposal here: #2646

We need this feature for another reason (bad performance of some key-exchange algorithms), but it would likely also solve this problem.

[ktbyers]

Fixed. Thanks @jonglezb .

[ktbyers]

Documenting for people that find this thread:

"disabled_algorithms": { "pubkeys": ["rsa-sha2-256","rsa-sha2-512"]}

Add that argument to ConnectHandler