For Red Hat-based distributions (RHEL, CentOS, Scientific Linux), the htpasswd utility is included in the httpd-tools package, not in a separate package like Ubuntu's apache2-utils. This can be confirmed with:

yum provides */htpasswd

Which should return output similar to:

httpd-tools-2.4.6-90.el7.x86_64 : Tools for use with the Apache HTTP Server
Repo        : base
Matched from:
Filename    : /usr/bin/htpasswd

To install the package, run:

sudo yum install httpd-tools

For newer versions using dnf:

sudo dnf install httpd-tools

After installation, you can use htpasswd to create or modify password files:

Create a new password file:

htpasswd -c /etc/httpd/.htpasswd username

Add another user to existing file (omit -c flag):

htpasswd /etc/httpd/.htpasswd anotheruser

Use bcrypt encryption (more secure than default crypt):

htpasswd -B /etc/httpd/.htpasswd secureuser

Here's a sample Apache configuration snippet for password protection:

<Directory "/var/www/protected">
    AuthType Basic
    AuthName "Restricted Content"
    AuthUserFile /etc/httpd/.htpasswd
    Require valid-user
</Directory>

Verify the installation by checking the version:

htpasswd -v

Common issues and solutions:

• Permission issues: Ensure Apache can read the .htpasswd file
• Syntax errors: Validate your Apache configuration with apachectl configtest
• Encryption method conflicts: Use consistent encryption methods when adding users

For batch user creation, you can use:

htpasswd -b /path/to/file username password

To verify a password against the file:

htpasswd -v /path/to/file username

While httpd-tools is the standard method, alternatives include:

1. Using OpenSSL to create passwords:

   openssl passwd -apr1
   

2. Using the Perl module (for scripting):

   yum install perl-Apache-Htpasswd
   

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For RHEL-based systems (including CentOS and Scientific Linux), the htpasswd utility comes bundled with the httpd-tools package, not apache2-utils like in Debian/Ubuntu systems. This is a common point of confusion when transitioning between Linux distributions.

# Search for the package:
yum search htpasswd
# Or for newer systems:
dnf search htpasswd

Execute these commands to install the httpd-tools package:

# For yum-based systems:
sudo yum install httpd-tools

# For dnf-based systems:
sudo dnf install httpd-tools

# Verify installation:
which htpasswd
# Should return: /usr/bin/htpasswd

Here are common use cases for htpasswd:

# Create new password file (-c flag creates file)
htpasswd -c /etc/httpd/.htpasswd user1

# Add additional users (omit -c flag)
htpasswd /etc/httpd/.htpasswd user2

# Using different encryption algorithms
htpasswd -bB /etc/httpd/.htpasswd user3 securepassword  # bcrypt
htpasswd -bm /etc/httpd/.htpasswd user4 securepassword  # MD5
htpasswd -bs /etc/httpd/.htpasswd user5 securepassword  # SHA1

Example configuration for password-protected directory:

<Directory "/var/www/html/protected">
    AuthType Basic
    AuthName "Restricted Access"
    AuthUserFile /etc/httpd/.htpasswd
    Require valid-user
</Directory>

Batch user creation (useful for automation):

# Create users from a list
for user in admin editor viewer; do
  htpasswd -b /etc/httpd/.htpasswd $user $(openssl rand -base64 12)
done

# Verify file contents
cat /etc/httpd/.htpasswd

Remember to set proper permissions on the password file:

chown apache:apache /etc/httpd/.htpasswd
chmod 640 /etc/httpd/.htpasswd

Common issues and solutions:

• Command not found: Verify httpd-tools is installed
• Authentication failures: Check file permissions and SELinux context
• Password file location: Best practice is to store outside web root