configurations-ansible/roles/hardening-basic/templates/etc/ssh/sshd_config.d/99-hardening.conf

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2022-11-21 12:56:57 +01:00
{% if hardening_sshd_enabled %}
Protocol 2 # Protocol 1 is fundamentally broken
StrictModes yes # Protects from misconfiguration
#ListenAddress [ip-here] # Listening address
Port {{ hardening_sshd_port }} # Listening port. Normal 22
AuthenticationMethods publickey # Only public key authentication allowed
AuthorizedKeysFile {{ hardening_sshd_authorized_key_file }}
PubkeyAuthentication yes # Allow public key authentication
HostKey /etc/ssh/ssh_host_ed25519_key # Only allow ECDSA pubic key authentication
HostKeyAlgorithms ssh-ed25519-cert-v01@openssh.com,ssh-ed25519 # Host keys the client should accepts
KexAlgorithms curve25519-sha256 # Specifies the available KEX (Key Exchange) algorithms
Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com # Specifies the ciphers allowed
MACs hmac-sha2-512-etm@openssh.com # Specifies the available MAC alg.
#Only allow incoming ECDSA and ed25519 sessions:
HostbasedAcceptedKeyTypes ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519
PubkeyAcceptedKeyTypes sk-ecdsa-sha2-nistp256@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519@openssh.com,ssh-ed25519
#CASignatureAlgorithms ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519
PermitRootLogin WITHOUT-PASSWORD # Enable/disable root login
#AllowUsers [username] # Authorized SSH users are inside the admin group
MaxAuthTries 5 # Maximum allowed authentication attempts
MaxSessions 2 # Maximum allowed sessions by the user
PasswordAuthentication no # No username password authentication
PermitEmptyPasswords no # No empty password authentcation allowed
IgnoreRhosts yes # Dont read users rhost files
HostbasedAuthentication no # Disable host-based authentication
ChallengeResponseAuthentication no # Unused authentication scheme
X11Forwarding no # Disable X11 forwarding
LogLevel VERBOSE # Fingerprint details of failed login attempts
SyslogFacility AUTH # Logging authentication and authorization related commands
UseDNS no # Client from a location without proper DNS generate a warning in the logs
PermitTunnel no # Only SSH connection and nothing else
AllowTcpForwarding {{ 'yes' if hardening_sshd_tcp_forward else 'no' }} # Disablow tunneling out via SSH
AllowStreamLocalForwarding no # Disablow tunneling out via SSH
GatewayPorts no # Disablow tunneling out via SSH
AllowAgentForwarding no # Do not allow agent forwarding
{% if hardening_sshd_legal_banner %}
Banner /etc/issue.net # Show legal login banner
{% endif %}
PrintLastLog yes # Show last login
ClientAliveInterval 900 # Client timeout (15 minutes)
ClientAliveCountMax 0 # This way enforces timeouts on the server side
LoginGraceTime 30 # Authenticatin must happen within 30 seconds
MaxStartups 2 # Max concurrent SSH sessions
TCPKeepAlive yes # Do not use TCP keep-alive
AcceptEnv LANG LC_* # Allow client to pass locale environment variables
{% endif %}