RSAAuthentication deprecated

[loodvn]

Hi there,

I'm getting the following warnings when using pxssh.login:

command-line line 0: Unsupported option "rsaauthentication"

My understanding is openSSH (https://www.openssh.com/releasenotes.html) and ssh_config (https://man.openbsd.org/ssh_config) dropped support for RSA authentication for quite some time.

It seems to come from whenever SSH_OPTS is used (

pexpect/pexpect/pxssh.py

Line 146 in acb017a

self.SSH_OPTS = ("-o'RSAAuthentication=no'"

), e.g. when self.force_password is True:

pexpect/pexpect/pxssh.py

Line 321 in 2be6c4d

if self.force_password:

Is that option still necessary or is PubkeyAuthentication=no sufficient?

Explanation of the deprecation that provided context for me: https://levelup.gitconnected.com/demystifying-ssh-rsa-in-openssh-deprecation-notice-22feb1b52acd (from https://askubuntu.com/a/1407251)

[Red-M]

Thanks but its recommended to move away from pxssh as per the notice in the documentation here.

I can't find the reference in the openssh's release notes that say they dropped RSAAuthentication support. I assume this might be a per distro option?

I'm happy to review a PR to remove the option but you are able to subclass pxssh.pxssh() to change it as a "monkey patch"

[loodvn]

Yeah I've struggled to get the precise note of the dropped support... Also I know veeeery little about OpenSSH/SSH haha, just trying to help out if there's a way to reduce users' confusion from this warning.

It seems from https://unix.stackexchange.com/questions/337774/deprecated-options-when-restarting-openssh-in-stretch and https://community.centminmod.com/threads/centos-7-4-sshd-deprecated-rsaauthentication.13137/ that after OpenSSH version 7.3+ they dropped support for SSH v1, which included the RSAAuthentication option.

And the last time I saw it in the ssh_config docs was here with OpenBSD-6.0:
RSAAuthentication
Specifies whether pure RSA authentication is allowed. The default is “yes”. This option applies to protocol version 1 only.

So I guess since SSH v1 is so old there's no harm in removing the option right? If so I'll put in a PR 👍

[Red-M]

I'm cautious of legacy breakage here is all, I think it has been an acceptable amount of time to remove that option since the last time it was in the docs was 2016.

[loodvn]

Thanks, and I think especially because SSHv1 hasn't been actively maintained since like early 2000s, but again, I'm a newbie to all this.
Putting in the PR now: #744