How To Allow Apache To Bind To Non-Standard Ports In SELinux?

Using semanage to Modify SELinux Port Rules

To solve the Apache port binding problem with SELinux, use the semanage tool. This tool lets you modify SELinux port rules and add new ports to the SELinux configuration.

Install the needed tools:

sudo yum -y install policycoreutils-python

This command installs the policycoreutils-python package, which includes the semanage tool.

To add a new port to the SELinux configuration, use this command:

sudo semanage port -a -t http_port_t -p tcp [PORT_NUMBER]

Replace [PORT_NUMBER] with the port you want to allow for Apache.

sudo semanage port -l | grep http_port_t

Step-by-Step Solution

1. Check current SELinux port settings: To see the current SELinux port settings for Apache, run:

   sudo semanage port -l | grep http_port_t

   This command lists all the ports allowed for Apache.

2. Add the new port to SELinux rules: Use the semanage command to add the new port. For example, to add port 88:

   sudo semanage port -a -t http_port_t -p tcp 88

3. Restart the Apache service: After adding the new port, restart Apache to apply the changes:

   sudo systemctl restart httpd

Temporary vs Permanent SELinux Rule Changes

Using semanage for permanent changes: The semanage command makes permanent changes to SELinux rules. These changes stay active after system reboots. This method works well for long-term setups where Apache needs to bind to specific non-standard ports.

Options for temporary changes: For temporary changes, you can use the 'setenforce' command to switch SELinux to permissive mode:

sudo setenforce 0

This command turns off SELinux enforcement for a short time, letting Apache bind to any port. This setting goes back to the default enforcing mode after a system reboot.

Security Implications

Balancing ease and security: Adding non-standard ports to SELinux rules for Apache gives more options but can reduce security. Each added port increases the risk of threats. Always compare the benefits of using non-standard ports with the higher security risk.

Best practices for non-standard port usage:

1. Add only ports that your applications need.
2. Check your SELinux port settings often to remove unused ports.
3. Use strong firewall rules to limit access to non-standard ports.
4. Check logs for unusual activity on these ports.
5. Keep your Apache server and related software up to date to reduce potential risks.

Using Apache with Different SELinux Contexts

Changing the SELinux context for Apache: You can change the SELinux context for Apache instead of modifying SELinux port rules. This method involves giving a different SELinux context to the Apache process, letting it bind to different ports.

To change the SELinux context for Apache:

1. Create a custom SELinux policy module:

   ausearch -c 'httpd' --raw | audit2allow -M my-httpd

2. Load the new policy module:

   semodule -i my-httpd.pp

Pros of this method:

• Apache can bind to any port without changing individual port rules.
• It offers a flexible solution for complex setups.

Cons of this method:

• It may give more permissions than needed, which could reduce security.
• It needs advanced knowledge of SELinux policies.
• Fixing issues can be harder if problems occur.

ps auxZ | grep httpd

Disabling SELinux (Not Recommended)

Why disabling SELinux is risky: Disabling SELinux removes a key security layer from your system. It makes your server more open to attacks and exploits. Some risks include:

• Higher risk of privilege escalation attacks
• Less protection against malware and unauthorized access
• Loss of audit logs that help detect and investigate security issues
• Possible compliance violations for systems that need SELinux

Situations where it might be considered: While not recommended, there are rare cases where you might think about disabling SELinux temporarily:

• During initial troubleshooting to find SELinux-related issues
• In controlled test environments for specific application testing
• When running old applications that don't work with SELinux and can't be changed

If you must disable SELinux, do it only for a short time and turn it back on as soon as possible. To disable SELinux, edit the /etc/selinux/config file and set SELINUX=disabled, then restart the system.