#  SSH Rootcheck
#
#  v1.0 2016/01/20
#  Created by Wazuh, Inc. <ossec@wazuh.com>.
#  jesus@wazuh.com
#  This program is a free software; you can redistribute it and/or modify it under the terms of GPLv2
#


$sshd_file=/etc/ssh/sshd_config;


# Listen PORT != 22
# The option Port specifies on which port number ssh daemon listens for incoming connections.
# Changing the default port you may reduce the number of successful attacks from zombie bots, an attacker or bot doing port-scanning can quickly identify your SSH port.
[SSH Hardening - 1: Port 22 {PCI_DSS: 2.2.4}] [any] [1]
f:$sshd_file -> !r:^# && r:Port\.+22;


# Protocol 2
# The Protocol parameter dictates which version of the SSH communication and encryption protocols are in use.
# Version 1 of the SSH protocol has weaknesses. 
[SSH Hardening - 2: Protocol 1 {PCI_DSS: 2.2.4}] [any] [2]
f:$sshd_file -> !r:^# && r:Protocol\.+1;


# PermitRootLogin no
# The option PermitRootLogin specifies whether root can log in using ssh.
# If you want log in as root, you should use the option "Match" and restrict it to a few IP addresses.
[SSH Hardening - 3: Root can log in] [any] [3]
f:$sshd_file -> !r:^# && r:PermitRootLogin\.+yes;
f:$sshd_file -> r:^#\s*PermitRootLogin;


# PubkeyAuthentication yes
# Access only by public key
# Generally people will use weak passwords and have poor password practices. Keys are considered stronger than password.
[SSH Hardening - 4: No Public Key autentication {PCI_DSS: 2.2.4}] [any] [4]
f:$sshd_file -> !r:^# && r:PubkeyAuthentication\.+no;
f:$sshd_file -> r:^#\s*PubkeyAuthentication;


# PasswordAuthentication no
# The option PasswordAuthentication specifies whether we should use password-based authentication.
# Use public key authentication instead of passwords
[SSH Hardening - 5: Password Authentication {PCI_DSS: 2.2.4}] [any] [5]
f:$sshd_file -> !r:^# && r:PasswordAuthentication\.+yes;
f:$sshd_file -> r:^#\s*PasswordAuthentication;


# PermitEmptyPasswords no
# The option PermitEmptyPasswords specifies whether the server allows logging in to accounts with a null password
# Accounts with null passwords are a bad practice.
[SSH Hardening - 6: Empty passwords allowed {PCI_DSS: 2.2.4}] [any] [6]
f:$sshd_file -> !r:^# && r:PermitEmptyPasswords\.+yes;
f:$sshd_file -> r:^#\s*PermitEmptyPasswords;


# IgnoreRhosts yes
# The option IgnoreRhosts specifies whether rhosts or shosts files should not be used in authentication.
# For security reasons it is recommended to no use rhosts or shosts files for authentication.
[SSH Hardening - 7: Rhost or shost used for authentication {PCI_DSS: 2.2.4}] [any] [7]
f:$sshd_file -> !r:^# && r:IgnoreRhosts\.+no;
f:$sshd_file -> r:^#\s*IgnoreRhosts;


# LoginGraceTime 30
# The option LoginGraceTime specifies how long in seconds after a connection request the server will wait before disconnecting if the user has not successfully logged in.
# 30 seconds is the recommended time for avoiding open connections without authenticate
[SSH Hardening - 8: Wrong Grace Time {PCI_DSS: 2.2.4}] [any] [8]
f:$sshd_file -> !r:^# && r:LoginGraceTime && !r:30\s*$;
f:$sshd_file -> r:^#\s*LoginGraceTime;


# MaxAuthTries 3
# The MaxAuthTries parameter specifices the maximum number of authentication attempts permitted per connection. Once the number of failures reaches half this value, additional failures are logged.
# This should be set to 3.
[SSH Hardening - 9: Wrong Maximum number of authentication attempts {PCI_DSS: 2.2.4}] [any] [9]
f:$sshd_file -> !r:^# && r:MaxAuthTries && !r:3\s*$;
f:$sshd_file -> r:^#\s*MaxAuthTries;
f:$sshd_file -> !r:MaxAuthTries;