Rework README.md

roles/sshd/README.md

@@ -1,35 +1,76 @@
 sshd
 ====
 
-Deploy a hardened `sshd` server
+A hardened OpenSSH server role for Debian/Ubuntu and RHEL/Rocky systems.
+
+This role installs and configures the `sshd` server with secure defaults and a small set of tunable options for authentication and forwarding.
 
 Requirements
 ------------
 
-None
+- Target hosts must be Debian-family or RedHat-family Linux systems
+
+Supported Platforms
+-------------------
+
+- Debian
+- Ubuntu
+- RHEL 9+
+- Rocky Linux 9+
 
 Role Variables
 --------------
 
-- `sshd_disable_pam`: whether to disable PAM support. Default: `false`
+Authentication
-- `sshd_password_auth`: whether to allow password authentication. Default: `false`
-- `sshd_challenge_response_auth`: whether to allow challenge-response authentication. Default: `false`
-- `sshd_gss_api_auth`: whether to allow GSSAPI authentication. Default: `false`
-- `sshd_allow_agent_forwarding`: whether to allow SSH agent forwarding. Default: `false`
-- `sshd_allow_tcp_forwarding`: whether to allow TCP forwarding. Default: `false`
-- `sshd_gateway_ports`: whether to allow gateway ports. Default: `false`
-- `sshd_permit_tunnel`: whether to allow SSH tunneling. Default: `false`
 
-Dependencies
+- `sshd_disable_pam`: disable PAM support in `sshd_config`. Default: `false`
-------------
+- `sshd_password_auth`: allow password authentication. Default: `false`
+- `sshd_challenge_response_auth`: allow challenge-response authentication. Default: `false`
+- `sshd_gss_api_auth`: allow GSSAPI authentication. Default: `false`
 
-None
+Forwarding & tunneling
+
+- `sshd_allow_agent_forwarding`: allow SSH agent forwarding. Default: `false`
+- `sshd_allow_tcp_forwarding`: allow TCP forwarding. Default: `false`
+- `sshd_gateway_ports`: allow gateway ports. Default: `false`
+- `sshd_permit_tunnel`: allow SSH tunneling. Default: `false`
+
+Access control
+
+- `sshd_allow_users`: optional space-separated list of users permitted to log in via SSH
+- `sshd_allow_groups`: optional space-separated list of groups permitted to log in via SSH
+
+Behavior
+--------
+
+By default this role:
+
+- installs `openssh-server`
+- enforces `Protocol 2`
+- disables `PermitRootLogin`
+- disables `X11Forwarding`, `HostbasedAuthentication`, `KbdInteractiveAuthentication`, and `PermitUserEnvironment`
+- disables weak(-er) host keys (`ecdsa`, `dsa`)
+- disables empty passwords
+- sets `LogLevel VERBOSE`
+- restricts `/etc/ssh/sshd_config` to `0600`
+
+Compatibility Notes
+-------------------
+
+- The role uses `sshd` validation via `/usr/sbin/sshd -t -f %s`.
+- Debian/Ubuntu systems use the `ssh` service name; RHEL/Rocky systems use `sshd`.
+- The role is intentionally conservative with forwarding and tunneling defaults.
 
 Example Playbook
 ----------------
 
 See: [converge.yml](molecule/default/converge.yml)
 
+Dependencies
+------------
+
+None
+
 License
 -------