Security Audit: Checklist with Commands

Introduction

Conducting regular security audits is fundamental to maintaining a robust security posture for Linux servers. Whether you're managing a single VPS or an enterprise infrastructure, systematic security assessments identify vulnerabilities, misconfigurations, and compliance gaps before attackers can exploit them.

This comprehensive security audit checklist provides system administrators, security professionals, and DevOps engineers with practical commands and procedures for thoroughly assessing Linux server security. Unlike automated scanning tools, manual auditing develops deep understanding of system security and uncovers issues that automated tools might miss.

A thorough security audit encompasses multiple dimensions: user authentication and authorization, network security, file system permissions, running services, patch management, logging and monitoring, cryptographic implementations, and compliance with security frameworks. This guide organizes these elements into a systematic checklist with specific commands for each verification.

Regular security audits serve multiple purposes: identifying security weaknesses, validating security controls, ensuring compliance with regulatory requirements, detecting unauthorized changes, and providing documentation for security assessments and certifications.

Pre-Audit Preparation

Documentation Gathering

Before starting the audit, collect essential documentation:

# System information
hostnamectl > /root/audit-$(date +%Y%m%d)/system-info.txt
uname -a >> /root/audit-$(date +%Y%m%d)/system-info.txt
cat /etc/os-release >> /root/audit-$(date +%Y%m%d)/system-info.txt

# Installed packages
dpkg -l > /root/audit-$(date +%Y%m%d)/packages-debian.txt  # Debian/Ubuntu
rpm -qa > /root/audit-$(date +%Y%m%d)/packages-rhel.txt    # RHEL/CentOS

# Network configuration
ip addr show > /root/audit-$(date +%Y%m%d)/network-config.txt
ip route show >> /root/audit-$(date +%Y%m%d)/network-config.txt
cat /etc/resolv.conf >> /root/audit-$(date +%Y%m%d)/network-config.txt

Create Audit Directory Structure

# Create organized audit directory
AUDIT_DIR="/root/security-audit-$(date +%Y%m%d-%H%M)"
mkdir -p $AUDIT_DIR/{system,users,network,services,files,logs,compliance}

# Set permissions
chmod 700 $AUDIT_DIR

Audit Logging Script

#!/bin/bash
# Create audit logging function
AUDIT_LOG="/root/security-audit-$(date +%Y%m%d).log"

log_audit() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" | tee -a $AUDIT_LOG
}

log_audit "=== Security Audit Started ==="

System Hardening Audit

Kernel Parameters Verification

# Check critical kernel parameters
log_audit "Checking kernel parameters..."

# IP forwarding (should be 0 unless router)
sysctl net.ipv4.ip_forward
[ ] Expected: 0

# SYN cookies (should be enabled)
sysctl net.ipv4.tcp_syncookies
[ ] Expected: 1

# ICMP redirects (should be disabled)
sysctl net.ipv4.conf.all.accept_redirects
sysctl net.ipv6.conf.all.accept_redirects
[ ] Expected: 0 for both

# Source routing (should be disabled)
sysctl net.ipv4.conf.all.accept_source_route
[ ] Expected: 0

# Log martian packets (should be enabled)
sysctl net.ipv4.conf.all.log_martians
[ ] Expected: 1

# Reverse path filtering (should be enabled)
sysctl net.ipv4.conf.all.rp_filter
[ ] Expected: 1

# Address space layout randomization
sysctl kernel.randomize_va_space
[ ] Expected: 2

# Kernel pointer restrictions
sysctl kernel.kptr_restrict
[ ] Expected: 1 or 2

# Dmesg restrictions
sysctl kernel.dmesg_restrict
[ ] Expected: 1

# Generate report
sysctl -a > $AUDIT_DIR/system/sysctl-current.txt

Boot and GRUB Security

# Check GRUB password protection
log_audit "Checking boot loader security..."

[ ] Check if GRUB is password protected
grep "password" /boot/grub/grub.cfg
grep "password" /boot/grub2/grub.cfg

# Check GRUB permissions
ls -l /boot/grub/grub.cfg
ls -l /boot/grub2/grub.cfg
[ ] Expected: 600 or 400

# Verify boot parameters
grep "GRUB_CMDLINE_LINUX" /etc/default/grub
[ ] Should contain: audit=1

System Updates and Patches

log_audit "Checking system updates..."

# Ubuntu/Debian
apt-get update
apt list --upgradable > $AUDIT_DIR/system/available-updates.txt
[ ] Review security updates

# Check for unattended upgrades
systemctl status unattended-upgrades
[ ] Should be active

# CentOS/RHEL
dnf check-update > $AUDIT_DIR/system/available-updates.txt
[ ] Review security updates

# Check last update
ls -lt /var/log/apt/history.log | head -5  # Debian/Ubuntu
ls -lt /var/log/dnf.log | head -5          # RHEL/CentOS
[ ] Verify recent updates

User and Authentication Audit

User Account Review

log_audit "Auditing user accounts..."

# List all users
cat /etc/passwd > $AUDIT_DIR/users/passwd.txt
[ ] Review all user accounts

# Find users with UID 0 (root privileges)
awk -F: '($3 == 0) {print}' /etc/passwd
[ ] Expected: Only root should have UID 0

# Check for users without passwords
awk -F: '($2 == "") {print}' /etc/shadow
[ ] Expected: No users without passwords

# Find users with no password expiry
awk -F: '($5 == "") {print $1}' /etc/shadow
[ ] Review and set expiry dates

# Check password aging
cat /etc/login.defs | grep -E "PASS_MAX_DAYS|PASS_MIN_DAYS|PASS_WARN_AGE"
[ ] PASS_MAX_DAYS should be ≤ 90
[ ] PASS_MIN_DAYS should be ≥ 1
[ ] PASS_WARN_AGE should be ≥ 7

# Review user password aging
for user in $(cut -d: -f1 /etc/passwd); do
    chage -l $user >> $AUDIT_DIR/users/password-aging.txt
done

Privileged Access Review

log_audit "Reviewing privileged access..."

# Check sudo configuration
cat /etc/sudoers > $AUDIT_DIR/users/sudoers.txt
ls -la /etc/sudoers.d/ >> $AUDIT_DIR/users/sudoers.txt
[ ] Verify NOPASSWD entries are justified
[ ] Verify ALL=(ALL:ALL) grants are necessary

# Find files with SUID/SGID bits
find / -xdev \( -perm -4000 -o -perm -2000 \) -type f -exec ls -l {} \; \
    > $AUDIT_DIR/files/suid-sgid.txt 2>/dev/null
[ ] Review all SUID/SGID binaries

# Check for unauthorized sudo access
grep -r "ALL=(ALL)" /etc/sudoers.d/
[ ] Verify each entry is authorized

SSH Configuration Audit

log_audit "Auditing SSH configuration..."

# Review SSH daemon configuration
grep -v "^#" /etc/ssh/sshd_config | grep -v "^$" > $AUDIT_DIR/network/sshd-config.txt

# Critical SSH settings to verify
grep "PermitRootLogin" /etc/ssh/sshd_config
[ ] Expected: PermitRootLogin no

grep "PasswordAuthentication" /etc/ssh/sshd_config
[ ] Expected: PasswordAuthentication no (if using keys)

grep "PermitEmptyPasswords" /etc/ssh/sshd_config
[ ] Expected: PermitEmptyPasswords no

grep "Protocol" /etc/ssh/sshd_config
[ ] Expected: Protocol 2

grep "MaxAuthTries" /etc/ssh/sshd_config
[ ] Expected: MaxAuthTries 3-6

grep "ClientAliveInterval" /etc/ssh/sshd_config
grep "ClientAliveCountMax" /etc/ssh/sshd_config
[ ] Should have timeout configured

grep "AllowUsers\|AllowGroups" /etc/ssh/sshd_config
[ ] Verify user restrictions if present

# Check SSH host keys
ls -l /etc/ssh/ssh_host_*
[ ] Verify strong algorithms (ED25519, RSA 4096)

# Check SSH authorized keys
for user_home in /home/*; do
    if [ -f "$user_home/.ssh/authorized_keys" ]; then
        echo "=== $user_home/.ssh/authorized_keys ===" >> $AUDIT_DIR/users/authorized-keys.txt
        cat "$user_home/.ssh/authorized_keys" >> $AUDIT_DIR/users/authorized-keys.txt
    fi
done
[ ] Review all authorized SSH keys

PAM Configuration

log_audit "Reviewing PAM configuration..."

# Check password quality requirements
cat /etc/security/pwquality.conf | grep -v "^#" | grep -v "^$"
[ ] minlen should be ≥ 14
[ ] dcredit, ucredit, lcredit, ocredit should be configured

# Check faillock configuration
cat /etc/security/faillock.conf | grep -v "^#" | grep -v "^$"
[ ] deny should be ≤ 5
[ ] unlock_time should be configured

# Review PAM files
ls -l /etc/pam.d/ > $AUDIT_DIR/users/pam-files.txt

Network Security Audit

Firewall Configuration

log_audit "Auditing firewall configuration..."

# UFW (Ubuntu/Debian)
ufw status verbose > $AUDIT_DIR/network/firewall-ufw.txt
[ ] Verify default deny incoming
[ ] Review allowed services

# Firewalld (CentOS/RHEL)
firewall-cmd --list-all > $AUDIT_DIR/network/firewall-firewalld.txt
[ ] Verify minimal open ports
[ ] Review active zones

# iptables (all systems)
iptables -L -n -v > $AUDIT_DIR/network/firewall-iptables.txt
ip6tables -L -n -v > $AUDIT_DIR/network/firewall-ip6tables.txt
[ ] Review all rules
[ ] Verify default DROP policy

# nftables
nft list ruleset > $AUDIT_DIR/network/firewall-nftables.txt

Open Ports and Listening Services

log_audit "Checking open ports and listening services..."

# List all listening TCP/UDP ports
ss -tuln > $AUDIT_DIR/network/listening-ports.txt
netstat -tuln >> $AUDIT_DIR/network/listening-ports.txt

# Identify processes on open ports
ss -tulpn > $AUDIT_DIR/network/listening-processes.txt
[ ] Verify each listening service is necessary
[ ] Verify services bind to appropriate interfaces

# Check for services listening on all interfaces
ss -tuln | grep "0.0.0.0\|:::"
[ ] Verify these services should be publicly accessible

# External port scan (if nmap available)
nmap -sT -p- localhost > $AUDIT_DIR/network/nmap-localhost.txt
[ ] Compare with expected services

Network Connections

log_audit "Reviewing active connections..."

# Current connections
ss -tupn > $AUDIT_DIR/network/active-connections.txt
[ ] Review for suspicious connections

# Routing table
ip route show > $AUDIT_DIR/network/routing-table.txt
[ ] Verify routing configuration

# DNS configuration
cat /etc/resolv.conf > $AUDIT_DIR/network/dns-config.txt
[ ] Verify DNS servers are trusted

# Network interfaces
ip link show > $AUDIT_DIR/network/interfaces.txt
[ ] Document all interfaces

Service and Process Audit

Running Services

log_audit "Auditing running services..."

# List all enabled services
systemctl list-unit-files --type=service --state=enabled \
    > $AUDIT_DIR/services/enabled-services.txt
[ ] Review each enabled service

# List all active services
systemctl list-units --type=service --state=running \
    > $AUDIT_DIR/services/running-services.txt
[ ] Verify each service is necessary

# Common unnecessary services to check
services_to_check="cups avahi-daemon bluetooth rpcbind nfs-server"
for service in $services_to_check; do
    systemctl is-active $service 2>/dev/null && \
        echo "WARNING: $service is running" | tee -a $AUDIT_LOG
done

Process Analysis

log_audit "Analyzing running processes..."

# All processes
ps aux > $AUDIT_DIR/services/processes.txt
[ ] Review for unexpected processes

# Processes running as root
ps aux | grep "^root" > $AUDIT_DIR/services/root-processes.txt
[ ] Verify necessity of root processes

# High CPU/Memory processes
ps aux --sort=-%cpu | head -20 > $AUDIT_DIR/services/high-cpu.txt
ps aux --sort=-%mem | head -20 > $AUDIT_DIR/services/high-memory.txt
[ ] Investigate resource-intensive processes

# Check for zombie processes
ps aux | grep "<defunct>" > $AUDIT_DIR/services/zombie-processes.txt
[ ] Should be minimal or none

File System and Permissions Audit

File System Mounts

log_audit "Auditing file system mounts..."

# Review mount options
mount > $AUDIT_DIR/files/current-mounts.txt
cat /etc/fstab > $AUDIT_DIR/files/fstab.txt

# Check for insecure mount options
mount | grep -E "nodev|nosuid|noexec"
[ ] /tmp should have: nodev,nosuid,noexec
[ ] /var/tmp should have: nodev,nosuid,noexec
[ ] /home should have: nodev,nosuid
[ ] /dev/shm should have: nodev,nosuid,noexec

# Verify separate partitions
df -h > $AUDIT_DIR/files/disk-usage.txt
[ ] /var should ideally be separate partition
[ ] /tmp should ideally be separate partition
[ ] /home should ideally be separate partition

Critical File Permissions

log_audit "Checking critical file permissions..."

# System files
ls -l /etc/passwd
[ ] Expected: 644

ls -l /etc/shadow
[ ] Expected: 640 or 000

ls -l /etc/group
[ ] Expected: 644

ls -l /etc/gshadow
[ ] Expected: 640 or 000

ls -l /etc/ssh/sshd_config
[ ] Expected: 600

ls -l /boot/grub/grub.cfg
[ ] Expected: 600 or 400

# Log files
ls -ld /var/log
[ ] Expected: 755 or 750

ls -l /var/log/auth.log
ls -l /var/log/secure
[ ] Expected: 640 or 600

World-Writable Files

log_audit "Finding world-writable files..."

# Find world-writable files
find / -xdev -type f -perm -0002 -ls 2>/dev/null \
    > $AUDIT_DIR/files/world-writable-files.txt
[ ] Review and justify each file

# Find world-writable directories
find / -xdev -type d -perm -0002 -ls 2>/dev/null \
    > $AUDIT_DIR/files/world-writable-dirs.txt
[ ] Review and justify each directory

# Verify sticky bit on /tmp
ls -ld /tmp
[ ] Should have sticky bit (drwxrwxrwt)

Orphaned Files

log_audit "Finding orphaned files..."

# Files without owner
find / -xdev -nouser -ls 2>/dev/null \
    > $AUDIT_DIR/files/no-owner.txt
[ ] Investigate orphaned files

# Files without group
find / -xdev -nogroup -ls 2>/dev/null \
    > $AUDIT_DIR/files/no-group.txt
[ ] Investigate orphaned files

Logging and Monitoring Audit

Log Configuration

log_audit "Auditing logging configuration..."

# Check rsyslog/syslog-ng
systemctl status rsyslog || systemctl status syslog-ng
[ ] Logging daemon should be active

# Review rsyslog configuration
cat /etc/rsyslog.conf > $AUDIT_DIR/logs/rsyslog-config.txt
ls -l /etc/rsyslog.d/ >> $AUDIT_DIR/logs/rsyslog-config.txt
[ ] Verify appropriate logging rules

# Check log rotation
cat /etc/logrotate.conf > $AUDIT_DIR/logs/logrotate-config.txt
ls -l /etc/logrotate.d/ >> $AUDIT_DIR/logs/logrotate-config.txt
[ ] Verify logs are rotated appropriately

Critical Logs Review

log_audit "Reviewing critical logs..."

# Authentication logs
tail -100 /var/log/auth.log > $AUDIT_DIR/logs/recent-auth.txt
tail -100 /var/log/secure >> $AUDIT_DIR/logs/recent-auth.txt
[ ] Review for failed login attempts

# Check for failed SSH attempts
grep "Failed password" /var/log/auth.log | tail -50
[ ] Investigate suspicious patterns

# System logs
tail -100 /var/log/syslog > $AUDIT_DIR/logs/recent-syslog.txt
tail -100 /var/log/messages >> $AUDIT_DIR/logs/recent-syslog.txt
[ ] Review for errors and warnings

# Kernel messages
dmesg > $AUDIT_DIR/logs/dmesg.txt
[ ] Review for hardware or kernel issues

Audit Daemon (auditd)

log_audit "Checking audit daemon..."

# Verify auditd is running
systemctl status auditd
[ ] Should be active and enabled

# Review audit rules
auditctl -l > $AUDIT_DIR/logs/audit-rules.txt
[ ] Verify comprehensive audit rules

# Check audit logs
ausearch -m USER_LOGIN -sv no | tail -20
[ ] Review failed login attempts

# Audit log space
df -h /var/log/audit
[ ] Ensure sufficient space

Cryptography and SSL/TLS Audit

SSL/TLS Certificates

log_audit "Auditing SSL/TLS certificates..."

# Find all certificates
find / -name "*.crt" -o -name "*.pem" 2>/dev/null \
    > $AUDIT_DIR/compliance/certificates.txt

# Check certificate expiration
for cert in /etc/ssl/certs/*.pem; do
    echo "=== $cert ===" >> $AUDIT_DIR/compliance/cert-expiry.txt
    openssl x509 -in $cert -noout -dates 2>/dev/null \
        >> $AUDIT_DIR/compliance/cert-expiry.txt
done
[ ] Verify certificates are not expired
[ ] Check expiration dates (30-90 days warning)

# Web server SSL configuration
if [ -f /etc/nginx/nginx.conf ]; then
    grep -r "ssl_" /etc/nginx/ > $AUDIT_DIR/network/nginx-ssl.txt
fi

if [ -f /etc/apache2/apache2.conf ]; then
    grep -r "SSLProtocol\|SSLCipherSuite" /etc/apache2/ \
        > $AUDIT_DIR/network/apache-ssl.txt
fi
[ ] Verify TLS 1.2 and 1.3 only
[ ] Verify strong cipher suites

SSH Key Analysis

log_audit "Analyzing SSH keys..."

# Check SSH key algorithms
for keyfile in /etc/ssh/ssh_host_*_key.pub; do
    echo "=== $keyfile ===" >> $AUDIT_DIR/network/ssh-keys.txt
    ssh-keygen -lf $keyfile >> $AUDIT_DIR/network/ssh-keys.txt
done
[ ] RSA keys should be ≥ 3072 bits
[ ] Prefer ED25519 keys

# Check user SSH keys
for user_home in /home/*; do
    if [ -d "$user_home/.ssh" ]; then
        echo "=== $user_home ===" >> $AUDIT_DIR/users/user-ssh-keys.txt
        find "$user_home/.ssh" -name "*.pub" -exec cat {} \; \
            >> $AUDIT_DIR/users/user-ssh-keys.txt 2>/dev/null
    fi
done

Malware and Intrusion Detection

Rootkit Detection

log_audit "Scanning for rootkits..."

# chkrootkit (if installed)
if command -v chkrootkit &> /dev/null; then
    chkrootkit > $AUDIT_DIR/compliance/chkrootkit.txt
    [ ] Review findings
fi

# rkhunter (if installed)
if command -v rkhunter &> /dev/null; then
    rkhunter --check --skip-keypress --report-warnings-only \
        > $AUDIT_DIR/compliance/rkhunter.txt
    [ ] Review findings
fi

File Integrity

log_audit "Checking file integrity..."

# AIDE (if installed)
if command -v aide &> /dev/null; then
    aide --check > $AUDIT_DIR/compliance/aide-check.txt
    [ ] Review changes
fi

# Check for recent modifications in critical directories
find /bin /sbin /usr/bin /usr/sbin -type f -mtime -7 \
    > $AUDIT_DIR/files/recent-binary-changes.txt
[ ] Verify legitimate changes

Compliance Checks

PCI-DSS Requirements

log_audit "PCI-DSS compliance checks..."

# Requirement 2: Strong passwords
grep "PASS_MIN_LENGTH\|minlen" /etc/login.defs /etc/security/pwquality.conf
[ ] Minimum 7 characters (recommend 14+)

# Requirement 8: Unique IDs
[ ] Verify no shared accounts

# Requirement 10: Track and monitor access
[ ] Verify auditd is running
[ ] Verify log retention ≥ 90 days

# Requirement 5: Anti-virus
systemctl status clamav-daemon 2>/dev/null
[ ] Verify anti-virus is running

# Requirement 1: Firewall
[ ] Verify firewall is active
[ ] Document all open ports

HIPAA Requirements

log_audit "HIPAA compliance checks..."

# Access controls (164.312(a)(1))
[ ] Verify unique user IDs
[ ] Verify automatic logoff (screen timeout)

# Audit controls (164.312(b))
[ ] Verify comprehensive logging
[ ] Verify log review procedures

# Integrity (164.312(c)(1))
[ ] Verify file integrity monitoring

# Transmission security (164.312(e)(1))
[ ] Verify encryption in transit (TLS)
[ ] Verify VPN for remote access

GDPR Requirements

log_audit "GDPR compliance checks..."

# Data encryption
[ ] Verify disk encryption (LUKS)
[ ] Verify backup encryption

# Access logging
[ ] Verify data access is logged
[ ] Verify log retention policy

# Data retention
[ ] Document data retention periods
[ ] Verify automatic deletion procedures

Automated Audit Script

#!/bin/bash
# Comprehensive Security Audit Script

AUDIT_DATE=$(date +%Y%m%d-%H%M%S)
AUDIT_DIR="/root/security-audit-$AUDIT_DATE"
AUDIT_LOG="$AUDIT_DIR/audit.log"

# Create directory structure
mkdir -p $AUDIT_DIR/{system,users,network,services,files,logs,compliance}

# Logging function
log_audit() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" | tee -a $AUDIT_LOG
}

log_audit "===== SECURITY AUDIT STARTED ====="

# System information
log_audit "Collecting system information..."
hostnamectl > $AUDIT_DIR/system/system-info.txt
uname -a >> $AUDIT_DIR/system/system-info.txt

# User audit
log_audit "Auditing users..."
awk -F: '($3 == 0) {print}' /etc/passwd > $AUDIT_DIR/users/uid-zero.txt
awk -F: '($2 == "") {print}' /etc/shadow > $AUDIT_DIR/users/no-password.txt

# Network audit
log_audit "Auditing network..."
ss -tuln > $AUDIT_DIR/network/listening-ports.txt
iptables -L -n -v > $AUDIT_DIR/network/firewall.txt

# Service audit
log_audit "Auditing services..."
systemctl list-unit-files --type=service --state=enabled \
    > $AUDIT_DIR/services/enabled-services.txt

# File system audit
log_audit "Auditing file system..."
find / -xdev -type f -perm -0002 -ls 2>/dev/null \
    > $AUDIT_DIR/files/world-writable.txt
find / -xdev \( -perm -4000 -o -perm -2000 \) -type f -ls 2>/dev/null \
    > $AUDIT_DIR/files/suid-sgid.txt

# Logging audit
log_audit "Auditing logs..."
tail -100 /var/log/auth.log > $AUDIT_DIR/logs/recent-auth.txt 2>/dev/null
tail -100 /var/log/secure >> $AUDIT_DIR/logs/recent-auth.txt 2>/dev/null

# Generate summary
log_audit "Generating summary..."
{
    echo "Security Audit Summary - $AUDIT_DATE"
    echo "======================================"
    echo ""
    echo "Users with UID 0: $(wc -l < $AUDIT_DIR/users/uid-zero.txt)"
    echo "Users without password: $(wc -l < $AUDIT_DIR/users/no-password.txt)"
    echo "Listening ports: $(wc -l < $AUDIT_DIR/network/listening-ports.txt)"
    echo "World-writable files: $(wc -l < $AUDIT_DIR/files/world-writable.txt)"
    echo "SUID/SGID files: $(wc -l < $AUDIT_DIR/files/suid-sgid.txt)"
    echo ""
    echo "Detailed results in: $AUDIT_DIR"
} > $AUDIT_DIR/SUMMARY.txt

log_audit "===== SECURITY AUDIT COMPLETED ====="

# Display summary
cat $AUDIT_DIR/SUMMARY.txt

# Email results
if command -v mail &> /dev/null; then
    mail -s "Security Audit: $(hostname) - $AUDIT_DATE" [email protected] \
        < $AUDIT_DIR/SUMMARY.txt
fi

Post-Audit Actions

Prioritizing Findings

# Create prioritized remediation plan
HIGH_PRIORITY="
- Users with UID 0 (other than root)
- Users without passwords
- Root SSH login enabled
- Weak password policies
- Missing security updates
"

MEDIUM_PRIORITY="
- Unnecessary services running
- Insecure mount options
- Missing file integrity monitoring
- Weak SSL/TLS configuration
"

LOW_PRIORITY="
- Log rotation configuration
- Documentation updates
- Monitoring enhancements
"

Remediation Tracking

# Create remediation tracking spreadsheet
cat > /root/remediation-plan.csv << EOF
Finding,Priority,Status,Assigned,Due Date,Completed
UID 0 users,High,Open,Admin,$(date -d '+7 days' +%Y-%m-%d),
Root SSH,High,Open,Admin,$(date -d '+7 days' +%Y-%m-%d),
Security updates,High,Open,Admin,$(date -d '+3 days' +%Y-%m-%d),
EOF

Best Practices

Regular Audit Schedule

• Weekly: Automated basic audit
• Monthly: Comprehensive manual audit
• Quarterly: Full compliance audit
• Annually: External security assessment

Documentation

• Maintain audit logs for compliance
• Document all findings and remediation
• Track security metrics over time
• Version control audit scripts

Continuous Improvement

• Refine audit checklist based on findings
• Automate repetitive checks
• Integrate with monitoring systems
• Regular security training

Conclusion

Regular security audits are essential for maintaining robust Linux server security. This comprehensive checklist provides a systematic approach to identifying vulnerabilities, misconfigurations, and compliance gaps.

Key takeaways:

Systematic Approach: Follow the checklist methodically to ensure comprehensive coverage of all security domains.

Documentation: Maintain detailed records of findings, remediation actions, and audit history for compliance and trend analysis.

Automation: Automate routine checks while maintaining manual review of critical security controls.

Continuous Process: Security auditing is ongoing, not a one-time event. Regular assessments detect configuration drift and emerging vulnerabilities.

Remediation Priority: Address critical findings immediately while scheduling lower-priority items appropriately.

By implementing this security audit checklist and maintaining regular assessment schedules, you establish proactive security monitoring that identifies and addresses vulnerabilities before they can be exploited, ensuring compliance with regulatory requirements and maintaining robust security posture.