Skip to main content

⚙️ Apache HTTPD – Configuration Guide

Apache uses a modular and flexible configuration system. The main file is typically:

  • RHEL/CentOS/Fedora: /etc/httpd/conf/httpd.conf
  • Debian/Ubuntu: /etc/apache2/apache2.conf

These include additional files and folders (conf.d/, sites-available/, mods-enabled/, etc.) using Include directives.

🧭 🔊 Listening: Listen​

Bind Apache to IP(s) and port(s). Default:

Listen 80
Listen 443

You can specify interfaces:

# Listen on specific IP and port (For Network Interface)
Listen 192.168.1.100:80

ℹ️ Only root can bind ports below 1024.

🌐 Server Identity​

ServerRoot "/etc/httpd"
ServerName example.com:80

# Disable server signature in error pages for security
ServerSignature Off

# Only show minimal server version details in headers
ServerTokens Prod
  • ServerName: Defines the canonical hostname/port
  • ServerSignature Off & ServerTokens Prod: Hide Apache version info for better security

📁 Document Root & Aliases​

DocumentRoot "/var/www/html"
<Directory "/var/www/html">
  Options Indexes FollowSymLinks

# Allow .htaccess to override settings
  AllowOverride All        
  Require all granted
</Directory>

# Map /docs URL path to a different directory
Alias /docs "/opt/docs/html"
<Directory "/opt/docs/html">
  Require all granted
</Directory>
  • DocumentRoot: Base directory for serving files
  • Alias: Maps a URL path to a different file system location

🛡️ Directory-Level Controls​


# Restrict access to a specific directory
<Directory "/var/www/html/private">
  Require ip 192.168.1.0/24

# Disallow .htaccess overrides in this directory
  AllowOverride None

# Disable all options (like Indexes, FollowSymLinks)
  Options None
</Directory>
  • Use <Directory>, <Files>, <Location> for access control

🌍 Virtual Hosts​

Apache supports name-based and IP-based virtual hosts:

<VirtualHost *:80>
  ServerName example.com
  ServerAlias www.example.com
  DocumentRoot "/var/www/example"
  ErrorLog "logs/example-error.log"
  CustomLog "logs/example-access.log" combined
</VirtualHost>

✅ Use apachectl -S to debug vhost issues

⏱️ Performance & Security Tuning​

# Wait 60 seconds max for client or server to respond -- Prevents hanging or delays
Timeout 60

# Reuse the connection for multiple requests --	Faster performance
KeepAlive On

# Allow 100 requests on one connection --	Limits overuse
MaxKeepAliveRequests 100

# Wait 5 seconds for next request	-- Save resources
KeepAliveTimeout 5

# Max size of the request line (like URL)	-- Blocks overly long URLs
LimitRequestLine 8190

# Max size of a header field --	Stops huge headers/cookies
LimitRequestFieldSize 8190
  • Optimize connection behavior with KeepAlive settings
  • Prevent abuse with header and line limits

🧪 Protocol Support: HTTP/2​

Protocols h2 http/1.1
ProtocolsHonorOrder On
  • Ensure TLS-enabled vhosts have HTTP/2 enabled for speed

🔒 SSL Setup​

Typically configured in ssl.conf:

Listen 443
<VirtualHost *:443>
  ServerName secure.example.com
  DocumentRoot "/var/www/secure"
  SSLEngine on
  SSLCertificateFile /etc/ssl/certs/example.crt
  SSLCertificateKeyFile /etc/ssl/private/example.key
  Protocols h2 http/1.1
</VirtualHost>
  • Use valid certs, and enforce secure protocols

🔄 If / ElseIf Conditions​

# If request comes from 10.1.0.0/16, allow access
<If "-R '10.1.0.0/16'">
  Require ip 10.1.0.0/16
</If>

# Else if request comes from 10.0.0.0/8, allow access
<ElseIf "-R '10.0.0.0/8'">
  Require ip 10.0.0.0/8
</ElseIf>


* Apache supports conditional logic in configurations

---

## 🧩 Modules & Includes

```apache
IncludeOptional conf.d/*.conf
IncludeOptional sites-enabled/*.conf
LoadModule rewrite_module modules/mod_rewrite.so
  • Modular approach keeps your config DRY and clean

✅ Testing & Reloading​

apachectl configtest   # Syntax check
systemctl reload httpd # Graceful reload
systemctl restart httpd
  • Always test before reload/restart to avoid downtime

🔍 Quick Directive Reference​

DirectiveDescription
ListenIP/port binding
ServerNameCanonical hostname
DocumentRootFilesystem base directory
AliasURL to filesystem path
ErrorLog, CustomLogLogging setup
Timeout, KeepAlive*Connection optimization
LimitRequest*Protection against large headers
<VirtualHost>Host-specific configurations
ProtocolsEnable HTTP/2 support
SSLEngine, SSLCert*TLS configuration

🎨 Pro Tips​

  • 💾 Backup before editing: Always make a copy of your config
  • 🧼 Minimal modules: Enable only the modules you use
  • 🔒 Harden SSL: Use strong ciphers, disable TLS 1.0/1.1
  • 🔍 Logs: Always check logs in /var/log/httpd/ or /var/log/apache2/

📘 This configuration guide should help you understand and master Apache's flexible and powerful setup system!