fix: allow ssh-rsa algorithm for Cisco network device connections

[IPvSean]

Summary

• OpenSSH 8.8+ disables ssh-rsa by default, but Cisco IOS-XE/C8K devices require it for public key authentication
• Added ansible_libssh_publickey_algorithms=ssh-rsa to the [cisco:vars] section in the student inventory template (instances_network.j2)
• Added ansible_libssh_publickey_algorithms=ssh-rsa to Cisco router (rtr1) host entries in the instructor inventory template (instructor_inventory_network.j2)
• Added PubkeyAcceptedAlgorithms +ssh-rsa and HostKeyAlgorithms +ssh-rsa to the SSH config (sshconfig.j2) deployed to control nodes, so direct SSH to routers also works

Error this fixes

fatal: [rtr1]: FAILED! => {"changed": false, "msg": "ssh connection failed: Failed to authenticate public key: The key algorithm 'ssh-rsa' is not allowed to be used by PUBLICKEY_ACCEPTED_TYPES configuration option"}

Test plan

• Provision a network workshop and verify ansible-navigator run playbook.yml --mode stdout succeeds against Cisco rtr1
• Verify student can SSH directly to rtr1 from the control node

Made with Cursor