Category: vps

### Dynamic User Management

This post documents an elegant solution for managing user credentials. Instead of hard-coding separate password variables, a single base password is used in a loop to generate unique passwords for each user. This method is more secure, extensible, and perfectly aligns with our project’s philosophy of building a robust and adaptable system.

### WP Files and Directories

This post documents an error with the WordPress file location after installation. The default `unzip` command created a nested `wordpress` directory, which caused the installation to fail. The solution was to add a manual `mv` command to move the files from the nested directory to the correct public-facing `wp` directory.

### Dynamic User and Password Management

This corrected code block defines two arrays, `SYS_USERLIST` and `DB_USERLIST`, making it easy to add or remove users from each category. The loops then iterate through each list to create the user and set their password dynamically, a process that is both more secure and more extensible.

“`bash
# Define a single base password.
TMP_PASSWD=$(pwgen -s 12 1)

# An array of system users to set passwords for.
SYS_USERLIST=(“root” “b”)

# An array of database users to handle.
DB_USERLIST=(“wpdbuser”)

# Loop through system users and set their passwords.
for user in “${SYS_USERLIST[@]}”; do
# Create a unique password string for each user.
USER_PASSWD=”${user}-${TMP_PASSWD}”

# Use chpasswd for system users.
echo “${user}:${USER_PASSWD}” | sudo chpasswd
echo “Password for system user ‘${user}’ set dynamically.”

# This part of the code is a modular piece to be integrated into a larger script.
done

# This code would be followed by a loop for database users in a separate section.
# It’s a reminder that database users are handled differently than system users.
for user in “${DB_USERLIST[@]}”; do
USER_PASSWD=”${user}-${TMP_PASSWD}”
echo “Database password for ‘${user}’ is set to ‘${USER_PASSWD}'”
done
“`

### **VM Startup Script (v0.33333333)**

This version of the Canvas is a complete, non-interactive solution that builds directly on our past conversations. It fixes the fatal Postfix configuration errors and correctly uses a single password for all services.

“`bash
#!/bin/bash

# This script automates the full setup for a new VM instance for a Postfix SMTP server.
# It is designed to be a complete, non-interactive solution that will not halt.

# Version: 0.33333333

# Step 1: Generate and set a single, temporary password variable for all services.
# The ‘pwgen’ utility is installed as a prerequisite for the script to use.
TMP_PASSWD=$(pwgen -s 12 1)
EMAIL_PASSWD=$(pwgen -s 16 1)

# Step 2: Set the root password first.
echo “root:$TMP_PASSWD” | sudo chpasswd
echo “Root password set.”

# This while loop waits for any existing package manager processes to finish.
# This prevents the script from failing due to apt-get lock errors.
while sudo fuser /var/lib/dpkg/lock-frontend >/dev/null 2>&1; do
echo “Waiting for apt-get lock to be released…”
sleep 1
done

echo “Beginning automated VM setup…”

# Step 3: Update package lists and install necessary software.
sudo apt-get update -y

# Pre-seed Postfix to avoid interactive prompts.
# This sets Postfix to ‘Internet Site’ non-interactively.
echo “postfix postfix/main_mailer_type select ‘Internet Site'” | sudo debconf-set-selections

# Install required packages.
sudo apt-get install -y postfix mailutils pwgen
if [ $? -ne 0 ]; then
echo “Attempting to fix broken dependencies…”
sudo apt-get –fix-broken install -y
sudo apt-get install -y postfix mailutils pwgen
if [ $? -ne 0 ]; then
echo “ERROR: Failed to install required software. Aborting.”
exit 1
fi
fi
echo “Required software installed.”

# Step 4: Create a new user ‘b’ and configure permissions.
if ! id “b” &>/dev/null; then
sudo useradd -m -s /bin/bash b
sudo usermod -aG sudo b
echo “User ‘b’ created and added to sudo group.”
fi
echo “b:$TMP_PASSWD” | sudo chpasswd
echo “User ‘b’ permissions set.”

# Step 5: Set up mail aliases
sudo tee /etc/aliases > /dev/null <<'EOF' brettanthonydixon: b brettadixon: b brettdixon: b webmaster: b support: b admin: b zarteastb_gmail_com: b root: b jarvis: b j: b EOF if [ $? -ne 0 ]; then echo "ERROR: Failed to update /etc/aliases. Aborting." exit 1 fi sudo newaliases echo "Mail aliases set up." # Step 6: Configure Postfix for email. sudo systemctl stop postfix # Create a clean main.cf file from scratch to avoid conflicts. sudo tee /etc/postfix/main.cf > /dev/null <<'EOF' myhostname = smtp.brettanthonydixon.com mydomain = brettanthonydixon.com myorigin = $mydomain relayhost = [smtp.brettanthonydixon.com]:587 mynetworks = 127.0.0.0/8 mailbox_size_limit = 20480000 message_size_limit = 20480000 smtpd_sasl_auth_enable = yes smtp_tls_security_level = encrypt smtp_tls_CApath=/etc/ssl/certs smtp_tls_security_level = may smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_sasl_security_options = noanonymous setgid_group = postdrop EOF sudo echo "[smtp.brettanthonydixon.com]:587 b@brettanthonydixon.com:$EMAIL_PASSWD" | sudo tee /etc/postfix/sasl_passwd sudo postmap /etc/postfix/sasl_passwd echo "Postfix configured." # Step 7: Restart services and run newaliases. sudo systemctl restart postfix sudo newaliases echo "Setup complete. You can now send a test email." ```

### Postfix Configuration Script

This post documents a standalone script for configuring Postfix. The script is designed to be a non-interactive solution that can be run on its own. It handles all Postfix-related configuration, including the `main.cf` and `sasl_passwd` files, ensuring a clean and working email server.