SSH looking for id_rsa-cert get key_load_public error

Question

1) My ~/.ssh folder has the permission: drwx------. 2 user user 4.0K Aug 19 15:39 .ssh

2) I run ssh-keygen -t rsa and get the defaults files id_rsa and id_rsa.pub.

3) I copy/paste my id_rsa.pub key to GitHub SSH Keys

4) When trying to connect via ssh -i id_rsa -vT [email protected] I get the following:

OpenSSH_7.5p1, OpenSSL 1.1.0f-fips 25 May 2017 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Reading configuration data /etc/ssh/ssh_config.d/05-redhat.conf debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config debug1: /etc/ssh/ssh_config.d/05-redhat.conf line 8: Applying options for * debug1: Connecting to github.com [192.30.253.113] port 22. debug1: Connection established. debug1: identity file id_rsa type 1 debug1: key_load_public: No such file or directory debug1: identity file id_rsa-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_7.5

I'm in doubt about how to generate the id_rsa-cert file.

I tried

openssl rsa -in ~/.ssh/id_rsa -outform pem > id_rsa-cert

and

openssl req -x509 -key ~/.ssh/id_rsa -nodes -days 9999 -newkey rsa:2048 -out id_rsa-cert

And it didn't work. Any tips?

Solution

I'm in doubt about how to generate the id_rsa-cert file.

You don't need it and certainly not for github access. The client is looking for a file named that way, but it does not mean that it is needed for normal SSH key authentication. For that, normal RSA key as you provided is enough.