System Configuration Analysis

System Configuration Analysis Skill

This skill provides detailed guidance for analyzing system configuration from sosreport archives, including OS information, installed packages, systemd services, and SELinux/AppArmor settings.

When to Use This Skill

Use this skill when:

• Analyzing the /sosreport:analyze command's system configuration phase
• Investigating service failures or misconfigurations
• Verifying package versions and updates
• Checking security policy settings (SELinux/AppArmor)
• Understanding system state and configuration

Prerequisites

• Sosreport archive must be extracted to a working directory
• Path to the sosreport root directory must be known
• Understanding of Linux system administration

Key Configuration Data Locations in Sosreport

1. System Information:

   • uname - Kernel version
   • etc/os-release - OS distribution and version
   • uptime - System uptime
   • proc/uptime - Uptime in seconds
   • sos_commands/release/ - Release information

2. Package Information:

   • installed-rpms - RPM packages (RHEL/Fedora/CentOS)
   • installed-debs - DEB packages (Debian/Ubuntu)
   • sos_commands/yum/ - Yum/DNF information
   • sos_commands/rpm/ - RPM database queries

3. Service Status:

   • sos_commands/systemd/systemctl_list-units - All units
   • sos_commands/systemd/systemctl_list-units_--failed - Failed units
   • sos_commands/systemd/systemctl_status_--all - Detailed service status
   • sos_commands/systemd/systemctl_list-unit-files - Unit files

4. SELinux:

   • sos_commands/selinux/sestatus - SELinux status
   • sos_commands/selinux/getenforce - Current enforcement mode
   • sos_commands/selinux/selinux-policy - Policy information
   • var/log/audit/audit.log - SELinux denials

5. AppArmor (if applicable):

   • sos_commands/apparmor/ - AppArmor configuration
   • etc/apparmor.d/ - AppArmor profiles

6. System Configuration Files:

   • etc/ - System-wide configuration
   • etc/sysctl.conf or etc/sysctl.d/ - Kernel parameters
   • etc/security/limits.conf - Resource limits

Implementation Steps

Step 1: Analyze System Information

1. Check OS version and distribution:

   if [ -f etc/os-release ]; then
     cat etc/os-release
   fi
   

2. Get kernel version:

   if [ -f uname ]; then
     cat uname
   elif [ -f proc/version ]; then
     cat proc/version
   fi
   

3. Check system uptime:

   if [ -f uptime ]; then
     cat uptime
   elif [ -f proc/uptime ]; then
     # Parse uptime from proc/uptime (seconds)
     awk '{printf "%.2f days\n", $1/86400}' proc/uptime
   fi
   

4. Extract key system details:

   • OS name and version
   • Kernel version
   • System architecture (x86_64, aarch64, etc.)
   • Uptime (days)

5. Check for outdated kernel or OS:

   • Compare kernel version with current stable
   • Note if system hasn't been rebooted in a very long time (>365 days)
   • Identify if OS version is EOL

Step 2: Analyze Installed Packages

1. List installed packages:

   # For RPM-based systems
   if [ -f installed-rpms ]; then
     cat installed-rpms
   fi
   
   # For DEB-based systems
   if [ -f installed-debs ]; then
     cat installed-debs
   fi
   

2. Extract key package versions:

   # Important system packages
   grep -E "^(kernel|systemd|glibc|openssh|openssl)" installed-rpms 2>/dev/null
   
   # Or use awk to parse package name and version
   awk '{print $1}' installed-rpms | head -20
   

3. Check for known problematic versions:

   • Security vulnerabilities (if known CVEs)
   • Buggy package versions
   • Compatibility issues

4. Identify package manager issues:

   # Check yum/dnf logs for errors
   if [ -d sos_commands/yum ]; then
     grep -i "error\|fail" sos_commands/yum/* 2>/dev/null
   fi
   

5. Count packages and categorize:

   • Total packages installed
   • Key package versions (kernel, systemd, glibc, etc.)
   • Recently updated packages (if timestamps available)

Step 3: Analyze Service Status

1. List all systemd units:

   if [ -f sos_commands/systemd/systemctl_list-units ]; then
     cat sos_commands/systemd/systemctl_list-units
   fi
   

2. Identify failed services:

   if [ -f sos_commands/systemd/systemctl_list-units_--failed ]; then
     cat sos_commands/systemd/systemctl_list-units_--failed
   elif [ -f sos_commands/systemd/systemctl_list-units ]; then
     grep "failed" sos_commands/systemd/systemctl_list-units
   fi
   

3. Check service details:

   # Parse detailed status for failed services
   if [ -f sos_commands/systemd/systemctl_status_--all ]; then
     # Extract service names and their status
     grep -E "●|Active:" sos_commands/systemd/systemctl_status_--all | head -50
   fi
   

4. Count services by state:

   # Count running, failed, inactive services
   if [ -f sos_commands/systemd/systemctl_list-units ]; then
     awk '{print $4}' sos_commands/systemd/systemctl_list-units | sort | uniq -c
   fi
   

5. Identify critical service failures:

   • System services (systemd-*, dbus, NetworkManager)
   • Application services (httpd, nginx, postgresql, etc.)
   • Custom services

6. Extract failure reasons from logs:

   # For each failed service, find related log entries
   grep -i "failed to start\|service.*failed" sos_commands/logs/journalctl_--no-pager 2>/dev/null | head -20
   

Step 4: Analyze SELinux Configuration

1. Check SELinux status:

   if [ -f sos_commands/selinux/sestatus ]; then
     cat sos_commands/selinux/sestatus
   fi
   

2. Get SELinux mode:

   if [ -f sos_commands/selinux/getenforce ]; then
     cat sos_commands/selinux/getenforce
   fi
   

3. Check for SELinux denials:

   # Look for AVC denials in audit log
   if [ -f var/log/audit/audit.log ]; then
     grep "avc.*denied" var/log/audit/audit.log | head -50
   fi
   
   # Or in journald logs
   grep -i "selinux.*denied\|avc.*denied" sos_commands/logs/journalctl_--no-pager 2>/dev/null | head -20
   

4. Parse denial information:

   • Extract denied operations (read, write, execute, etc.)
   • Identify source and target contexts
   • Note which services are affected

5. Check for SELinux booleans:

   if [ -f sos_commands/selinux/getsebool_-a ]; then
     cat sos_commands/selinux/getsebool_-a
   fi
   

6. Identify SELinux issues:

   • SELinux in permissive mode (may hide errors)
   • SELinux disabled (security concern)
   • Frequent AVC denials (policy may need adjustment)
   • Context mismatches

Step 5: Check System Configuration

1. Review kernel parameters:

   # Check sysctl settings
   if [ -f sos_commands/kernel/sysctl_-a ]; then
     cat sos_commands/kernel/sysctl_-a
   elif [ -d etc/sysctl.d ]; then
     cat etc/sysctl.d/*.conf 2>/dev/null
   fi
   

2. Check resource limits:

   if [ -f etc/security/limits.conf ]; then
     grep -v "^#\|^$" etc/security/limits.conf
   fi
   
   # Check limits.d directory
   if [ -d etc/security/limits.d ]; then
     cat etc/security/limits.d/*.conf 2>/dev/null
   fi
   

3. Review boot parameters:

   if [ -f sos_commands/boot/grub2-editenv_list ]; then
     cat sos_commands/boot/grub2-editenv_list
   elif [ -f proc/cmdline ]; then
     cat proc/cmdline
   fi
   

4. Check systemd configuration:

   # Look for systemd configuration overrides
   if [ -d etc/systemd/system ]; then
     find etc/systemd/system -name "*.conf" 2>/dev/null
   fi
   

Step 6: Generate System Configuration Summary

Create a structured summary with the following sections:

1. System Information:

   • OS name and version
   • Kernel version
   • Architecture
   • System uptime
   • Last boot time

2. Package Summary:

   • Total packages installed
   • Key package versions (kernel, systemd, glibc, openssl, openssh)
   • Known problematic packages (if any)
   • Package manager issues

3. Service Status:

   • Total services
   • Running services count
   • Failed services count
   • List of failed services with reasons
   • Critical service status

4. SELinux/AppArmor:

   • SELinux status (enabled/disabled)
   • SELinux mode (enforcing/permissive)
   • Denial count
   • Top denied operations
   • Policy recommendations

5. Configuration Issues:

   • Kernel parameter anomalies
   • Resource limit issues
   • Boot parameter problems
   • Configuration file errors

Error Handling

1. Missing configuration files:

   • Different distributions have different file locations
   • Some files may not be collected based on sosreport options
   • Document missing data in summary

2. Package manager variations:

   • Handle both RPM and DEB systems
   • Account for different package naming conventions
   • Support multiple package managers (yum, dnf, apt)

3. SELinux vs AppArmor:

   • Check which MAC system is in use
   • Analyze accordingly
   • Note if both or neither are present

4. Systemd vs init:

   • Older systems may use init instead of systemd
   • Check for both service management systems
   • Adapt analysis based on what's present

Output Format

The system configuration analysis should produce:

SYSTEM CONFIGURATION SUMMARY
============================

SYSTEM INFORMATION
------------------
OS: {os_name} {os_version}
Kernel: {kernel_version}
Architecture: {arch}
Uptime: {uptime_days} days ({last_boot_time})

Status: {OK|WARNING|CRITICAL}
Notes:
  - {system_info_note}

INSTALLED PACKAGES
------------------
Total Packages: {count}

Key Package Versions:
  kernel: {version}
  systemd: {version}
  glibc: {version}
  openssl: {version}
  openssh-server: {version}

Status: {OK|WARNING|CRITICAL}
Issues:
  - {package_issue_description}

SYSTEMD SERVICES
----------------
Total Units: {total}
Active: {active_count}
Failed: {failed_count}
Inactive: {inactive_count}

Failed Services:
  ● {service_name}.service - {description}
    Reason: {failure_reason}
    Last Failed: {timestamp}

  ● {service_name}.service - {description}
    Reason: {failure_reason}
    Last Failed: {timestamp}

Status: {OK|WARNING|CRITICAL}
Recommendations:
  - {service_recommendation}

SELINUX
-------
Status: {enabled|disabled}
Mode: {enforcing|permissive|disabled}
Policy: {policy_name}

AVC Denials: {count} denials found

Top Denied Operations:
  [{count}x] {operation} on {target} by {source}
  [{count}x] {operation} on {target} by {source}

SELinux Booleans: {count} custom settings

Status: {OK|WARNING|CRITICAL}
Issues:
  - {selinux_issue_description}

Recommendations:
  - {selinux_recommendation}

KERNEL PARAMETERS
-----------------
Key sysctl Settings:
  vm.swappiness: {value}
  net.ipv4.ip_forward: {value}
  kernel.panic: {value}

Custom Parameters: {count} custom settings found

Status: {OK|WARNING|CRITICAL}
Notes:
  - {kernel_param_note}

RESOURCE LIMITS
---------------
Custom Limits Found: {count}

{user_or_group}  {type}  {item}  {value}

Status: {OK|WARNING}
Notes:
  - {limits_note}

CRITICAL CONFIGURATION ISSUES
-----------------------------
{severity}: {issue_description}
  Evidence: {file_path}
  Impact: {impact_description}
  Recommendation: {remediation_action}

RECOMMENDATIONS
---------------
1. {actionable_recommendation}
2. {actionable_recommendation}

DATA SOURCES
------------
- OS Info: {sosreport_path}/etc/os-release
- Kernel: {sosreport_path}/uname
- Packages: {sosreport_path}/installed-rpms
- Services: {sosreport_path}/sos_commands/systemd/systemctl_list-units
- SELinux: {sosreport_path}/sos_commands/selinux/sestatus
- Audit Log: {sosreport_path}/var/log/audit/audit.log

Examples

Example 1: Failed Service Analysis

# List failed services
$ cat sos_commands/systemd/systemctl_list-units_--failed
  UNIT                    LOAD   ACTIVE SUB    DESCRIPTION
● httpd.service          loaded failed failed Apache Web Server
● postgresql.service     loaded failed failed PostgreSQL database

# Find failure reason in logs
$ grep "httpd.service" sos_commands/logs/journalctl_--no-pager | grep -i "failed\|error"
Jan 15 10:23:45 server systemd[1]: httpd.service: Main process exited, code=exited, status=1/FAILURE
Jan 15 10:23:45 server systemd[1]: httpd.service: Failed with result 'exit-code'
Jan 15 10:23:45 server httpd[12345]: (98)Address already in use: AH00072: make_sock: could not bind to address [::]:80

# Interpretation: httpd failed because port 80 is already in use

Example 2: SELinux Denial Analysis

# Check for AVC denials
$ grep "avc.*denied" var/log/audit/audit.log | head -5
type=AVC msg=audit(1705320245.123:456): avc: denied { write } for pid=1234 comm="httpd" name="index.html" dev="sda1" ino=789012 scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:object_r:user_home_t:s0 tclass=file permissive=0

# Interpretation:
# - httpd (web server) was denied write access
# - Target file: index.html with context user_home_t
# - Issue: Web server trying to write to user home directory
# - Solution: Fix file context or move file to proper location

Example 3: Package Version Check

# Check for specific package versions
$ grep "^openssl" installed-rpms
openssl-1.1.1k-7.el8_6.x86_64
openssl-libs-1.1.1k-7.el8_6.x86_64

$ grep "^kernel" installed-rpms
kernel-4.18.0-425.el8.x86_64
kernel-4.18.0-477.el8.x86_64
kernel-core-4.18.0-425.el8.x86_64
kernel-core-4.18.0-477.el8.x86_64

# Interpretation:
# - OpenSSL version 1.1.1k (check for known CVEs)
# - Multiple kernels installed (good for rollback)
# - Current kernel is 4.18.0-477 (from uname)

Tips for Effective Analysis

1. Check service dependencies: Failed service may be due to dependency failure
2. Correlate with logs: Service failures often have detailed errors in logs
3. Verify configurations: Check service config files for syntax errors
4. Consider timing: When did service fail? Correlate with system events
5. SELinux context matters: File contexts must match policy expectations
6. Package versions: Compare with known good/bad versions
7. Uptime significance: Very long uptime may mean missed security updates

Common Configuration Patterns and Issues

1. Service dependency failure: ServiceB fails because ServiceA is not running
2. Port conflict: Service fails to bind - port already in use
3. Permission denied: Service can't access required files/directories
4. SELinux blocking: Service denied access by SELinux policy
5. Missing dependencies: Required package not installed
6. Configuration error: Syntax error in config file
7. Resource limits: Service hits ulimit (open files, processes, etc.)
8. Outdated kernel: Running kernel doesn't match installed packages

Configuration Issue Severity Classification

See Also

• Logs Analysis Skill: For detailed service failure log analysis
• Resource Analysis Skill: For resource limit issues
• Network Analysis Skill: For network service configuration

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