Security Hardening Guide

Overview

This guide provides a structured hardening walkthrough for Xloud Cloud Platform nodes. Apply these controls before the first production deployment. The checklist at the end of this page provides a verification reference for compliance audits. Hardening operates at four levels: the host operating system (XOS), the Xloud platform services, supporting infrastructure components (database, message queue), and the metadata service.

Xloud-Developed — XAVS ships with automated hardening roles that enforce CIS benchmarks out of the box. Automated controls include SSH hardening and allowlisting, audit logging configuration, Docker security benchmarks, and AppArmor profile enforcement. These roles run during initial deployment and can be re-applied at any time via xavs-ansible reconfigure --tags hardening.

Prerequisites

XOS installed on all control and compute nodes
XDeploy access with bootstrap credentials
SSH access to all cluster nodes
A change management window — some steps require service restarts

Apply hardening before deploying production workloads. Some controls (such as disabling unused kernel modules) require a reboot. Schedule accordingly.

OS Hardening

Configure SSH

Restrict SSH to key-based authentication and disable direct root login on all nodes:

Harden SSH configuration

cat >> /etc/ssh/sshd_config << 'EOF'
PermitRootLogin no
PasswordAuthentication no
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys
X11Forwarding no
AllowTcpForwarding no
MaxAuthTries 3
ClientAliveInterval 300
ClientAliveCountMax 2
LoginGraceTime 30
EOF

systemctl restart sshd

Verify: ssh root@<node> is rejected. Key-based login as the xloud user succeeds.

Enable automatic security updates

Configure unattended upgrades for security patches:

Configure unattended upgrades

apt-get install -y unattended-upgrades apt-listchanges

cat > /etc/apt/apt.conf.d/50unattended-upgrades << 'EOF'
Unattended-Upgrade::Allowed-Origins {
  "${distro_id}:${distro_codename}-security";
};
Unattended-Upgrade::AutoFixInterruptedDpkg "true";
Unattended-Upgrade::MinimalSteps "true";
Unattended-Upgrade::Mail "security@your-org.com";
Unattended-Upgrade::Remove-Unused-Kernel-Packages "true";
Unattended-Upgrade::Remove-Unused-Dependencies "true";
EOF

systemctl enable unattended-upgrades
systemctl start unattended-upgrades

Configure host firewall (ufw)

Restrict inbound traffic to required service ports only:

Configure ufw on control nodes

ufw default deny incoming
ufw default allow outgoing
ufw allow from 10.0.0.0/8 to any port 22    # SSH from management network
ufw allow from 10.0.0.0/8 to any port 443   # HTTPS API
ufw allow from 10.0.0.0/8 to any port 5000  # Keystone
ufw allow from 10.0.0.0/8 to any port 8774  # Nova API
ufw allow from 10.0.0.0/8 to any port 9696  # Neutron
ufw enable

Configure ufw on compute nodes

ufw default deny incoming
ufw default allow outgoing
ufw allow from 10.0.0.0/8 to any port 22      # SSH
ufw allow from 10.0.0.0/8 to any port 16509   # libvirt
ufw allow from 10.0.0.0/8 to any port 49152:49215/tcp  # live migration
ufw enable

Disable unused kernel modules

Remove attack surface by disabling kernel modules that are not required:

Disable unused modules

cat > /etc/modprobe.d/hardening.conf << 'EOF'
# Disable uncommon filesystems
install cramfs /bin/true
install freevxfs /bin/true
install jffs2 /bin/true
install hfs /bin/true
install hfsplus /bin/true
install squashfs /bin/true
install udf /bin/true

# Disable uncommon network protocols
install dccp /bin/true
install sctp /bin/true
install rds /bin/true
install tipc /bin/true
EOF

Configure kernel security parameters

Apply kernel hardening via sysctl

cat > /etc/sysctl.d/99-hardening.conf << 'EOF'
# Network hardening
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1
net.ipv4.tcp_syncookies = 1
net.ipv4.conf.all.log_martians = 1

# Memory hardening
kernel.randomize_va_space = 2
kernel.dmesg_restrict = 1
kernel.kptr_restrict = 2
fs.protected_hardlinks = 1
fs.protected_symlinks = 1
EOF

sysctl -p /etc/sysctl.d/99-hardening.conf

Enable AppArmor enforcement

AppArmor profiles for hypervisor processes ship in enforce mode on XOS. Verify and enable:

Verify AppArmor status

aa-status | grep -E "profiles|enforce|complain"

Switch complain-mode profiles to enforce:

Enforce all complain-mode profiles

for profile in $(aa-status --json | python3 -c "
import sys, json
d = json.load(sys.stdin)
for p in d.get('complain', []): print(p)
"); do
  aa-enforce /etc/apparmor.d/$profile 2>/dev/null || true
done

Run aa-status and confirm no profiles remain in complain mode for hypervisor-related processes.

Service Hardening

Minimize running services

Disable services that are not required on each node type:

Disable unused services on control nodes

# Services not needed on a dedicated control plane node
systemctl disable --now cups bluetooth avahi-daemon
systemctl mask cups bluetooth avahi-daemon

Disable unused services on compute nodes

systemctl disable --now cups bluetooth
systemctl mask cups bluetooth

Set file permission baselines

Restrict sensitive configuration files

chmod 600 /etc/xavs/passwords.yml
chmod 750 /etc/xavs/
find /etc/xavs/certificates/ -type f -name "*.key" -exec chmod 600 {} \;

Harden the metadata service

The instance metadata service is accessible at 169.254.169.254 from all VMs. Enable the shared secret to prevent unauthorized cross-tenant metadata access:

/etc/xavs/globals.d/_60_metadata.yml

neutron_metadata_proxy_shared_secret: "<generate with: openssl rand -hex 32>"
nova_metadata_enabled: "yes"

Deploy metadata hardening

xavs-ansible reconfigure --tags nova,neutron

Configure audit daemon (auditd)

Install and configure auditd

apt-get install -y auditd audispd-plugins

cat >> /etc/audit/rules.d/hardening.rules << 'EOF'
# Monitor privileged command execution
-a always,exit -F arch=b64 -S execve -F euid=0 -k privileged
# Monitor file permission changes on sensitive paths
-w /etc/passwd -p wa -k identity
-w /etc/shadow -p wa -k identity
-w /etc/xavs/passwords.yml -p rwa -k xavs-passwords
# Monitor network configuration changes
-a always,exit -F arch=b64 -S sethostname -S setdomainname -k network-config
EOF

augenrules --load
systemctl enable auditd
systemctl start auditd

Database Hardening

Remove anonymous and test accounts

Audit MariaDB accounts

docker exec mariadb mysql -uroot -p"${MYSQL_ROOT_PASSWORD}" \
  -e "SELECT user, host, password FROM mysql.user ORDER BY user;"

Remove any anonymous accounts and the test database if present.

Restrict remote root access

Disable remote root login

docker exec mariadb mysql -uroot -p"${MYSQL_ROOT_PASSWORD}" \
  -e "DELETE FROM mysql.user WHERE User='root' AND Host != 'localhost'; FLUSH PRIVILEGES;"

Enable binary log encryption

/etc/xavs/globals.d/_60_db_security.yml

mariadb_enable_binlog: "yes"
mariadb_binlog_format: "ROW"
mariadb_expire_logs_days: "7"

Message Queue Hardening

Enable RabbitMQ TLS

/etc/xavs/globals.d/_60_rabbitmq.yml

rabbitmq_enable_tls: "yes"
rabbitmq_management_enabled: "yes"

Remove default guest account

The guest account in RabbitMQ is restricted to localhost by default in the Xloud deployment. Verify it is not accessible remotely:

Verify guest user restrictions

docker exec rabbitmq rabbitmqctl list_users
# guest user should not appear, or should be tagged as non-admin

Set queue and message TTLs

Configure message TTLs to prevent message queue buildup from accumulating sensitive data:

RabbitMQ TTL policy

rabbitmq_message_ttl: "3600000"
rabbitmq_queue_ttl: "86400000"

Pre-Deployment Hardening Checklist

Use this checklist to verify hardening is complete before going to production.

Category	Control	Verification Command
SSH	Root login disabled	`grep PermitRootLogin /etc/ssh/sshd_config`
SSH	Password auth disabled	`grep PasswordAuthentication /etc/ssh/sshd_config`
OS	Auto-updates active	`systemctl is-enabled unattended-upgrades`
OS	Host firewall enabled	`ufw status`
OS	ASLR enabled	`sysctl kernel.randomize_va_space`
OS	AppArmor enforcing	`aa-status --json \| python3 -c "import sys,json; d=json.load(sys.stdin); print(len(d.get('enforce',[])))"`
Services	Unused services disabled	`systemctl list-units --state=active --type=service`
TLS	External TLS active	`openssl s_client -connect <vip>:443 \| openssl x509 -noout -enddate`
TLS	Internal TLS active	`grep "enable_tls_internal" /etc/xavs/globals.d/_60_tls.yml`
Certs	Certificate not expired	`openssl x509 -in /etc/xavs/certificates/haproxy.crt -noout -enddate`
Permissions	Passwords files restricted	`stat -c "%a %U %G" /etc/xavs/passwords.yml`
Metadata	Shared secret set	`grep "neutron_metadata_proxy_shared_secret" /etc/xavs/globals.d/`
Database	No anonymous users	`docker exec mariadb mysql -e "SELECT user,host FROM mysql.user WHERE user=''"`
Audit	auditd running	`systemctl is-active auditd`
Audit	Audit rules loaded	`auditctl -l \| wc -l`

Next Steps

Infrastructure Security

TLS configuration and certificate management

Compliance

Map hardening controls to SOC 2, ISO 27001, and PCI-DSS requirements

Network Security

Security groups, FWaaS, and network segmentation

Troubleshooting

Diagnose and resolve common security configuration issues

Core Services

Other Services

Security Hardening Guide

Overview

OS Hardening

Configure SSH

Enable automatic security updates

Configure host firewall (ufw)

Disable unused kernel modules

Configure kernel security parameters

Enable AppArmor enforcement

Service Hardening

Minimize running services

Set file permission baselines

Harden the metadata service

Configure audit daemon (auditd)

Database Hardening

Remove anonymous and test accounts

Restrict remote root access

Enable binary log encryption

Message Queue Hardening

Enable RabbitMQ TLS

Remove default guest account

Set queue and message TTLs

Pre-Deployment Hardening Checklist

Next Steps

Infrastructure Security

Compliance

Network Security

Troubleshooting

Core Services

Other Services

​Overview

​OS Hardening

Configure SSH

Enable automatic security updates

Configure host firewall (ufw)

Disable unused kernel modules

Configure kernel security parameters

Enable AppArmor enforcement

​Service Hardening

Minimize running services

Set file permission baselines

Harden the metadata service

Configure audit daemon (auditd)

​Database Hardening

Remove anonymous and test accounts

Restrict remote root access

Enable binary log encryption

​Message Queue Hardening

Enable RabbitMQ TLS

Remove default guest account

Set queue and message TTLs

​Pre-Deployment Hardening Checklist

​Next Steps

Infrastructure Security

Compliance

Network Security

Troubleshooting

Overview

OS Hardening

Service Hardening

Database Hardening

Message Queue Hardening

Pre-Deployment Hardening Checklist

Next Steps