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90 lines
3.2 KiB
Bash
90 lines
3.2 KiB
Bash
#!/bin/bash
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# Define constants
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SSH_CONFIG_FILE="/etc/ssh/sshd_config"
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AUTH_LINE="PasswordAuthentication"
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# --- Function to check the current state ---
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get_current_state() {
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# Using -E for extended regular expressions instead of -P for broader compatibility
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# 1. Use grep to find the line, including commented lines
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# 2. Use sed to remove leading/trailing whitespace and the setting name
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# 3. Use tr to convert to lowercase for reliable comparison
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CURRENT_STATE=$(grep -iE "^\s*#?\s*${AUTH_LINE}\s+" "$SSH_CONFIG_FILE" 2>/dev/null | \
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sed -E "s/^\s*#?\s*${AUTH_LINE}\s*//" | \
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tr '[:upper:]' '[:lower:]' | \
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head -n 1)
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# If the line is not found, or is commented out/blank, default to 'no' (SSH default security)
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if [[ -z "$CURRENT_STATE" || "$CURRENT_STATE" == "no" ]]; then
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echo "no"
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elif [[ "$CURRENT_STATE" == "yes" ]]; then
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echo "yes"
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else
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# Handle cases where the setting is missing or invalid. Check for an explicit 'no'.
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if grep -qE "^\s*${AUTH_LINE}\s+no" "$SSH_CONFIG_FILE" 2>/dev/null; then
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echo "no"
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else
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echo "no" # Defaulting to the most secure setting if not explicitly 'yes'
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fi
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fi
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}
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# --- Main Toggler Logic ---
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current=$(get_current_state)
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if [ "$current" == "yes" ]; then
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NEW_STATE="no"
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ACTION="DISABLE"
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WARNING="WARNING: This will DISABLE password authentication and only allow SSH keys!"
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elif [ "$current" == "no" ]; then
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NEW_STATE="yes"
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ACTION="ENABLE"
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WARNING="DANGER: This will ENABLE password authentication, increasing brute-force risk!"
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else
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echo "Error: Could not determine current state of $AUTH_LINE."
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exit 1
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fi
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echo "---"
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echo "Current state of ${AUTH_LINE} is: **$current**"
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echo "$WARNING"
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read -r -p "Do you want to $ACTION password authentication? (y/N): " response
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if [[ "$response" =~ ^([yY])$ ]]; then
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echo "Applying changes..."
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# Use 'sed' for safe, idempotent change with a backup
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# 1. Substitute any existing line with the new one.
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sudo sed -i.bak -E "s/^\s*#?\s*${AUTH_LINE}\s+(yes|no)/${AUTH_LINE} ${NEW_STATE}/" "$SSH_CONFIG_FILE"
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# 2. If the line was missing or not matched (a rare edge case), ensure it is added
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if ! grep -qE "^\s*${AUTH_LINE}\s+${NEW_STATE}" "$SSH_CONFIG_FILE" 2>/dev/null; then
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echo "${AUTH_LINE} ${NEW_STATE}" | sudo tee -a "$SSH_CONFIG_FILE" > /dev/null
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fi
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# Restart the SSH service
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echo "Restarting sshd to apply the new configuration..."
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if command -v systemctl &> /dev/null; then
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sudo systemctl restart sshd || sudo systemctl restart ssh
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elif [ -f /etc/init.d/sshd ]; then
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sudo /etc/init.d/sshd restart
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else
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echo "Error: Could not find a command to restart the SSH service. Please restart it manually."
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exit 1
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fi
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# Final verification
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new_current=$(get_current_state)
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echo "Verification: New state of ${AUTH_LINE} is: **$new_current**"
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if [ "$new_current" == "$NEW_STATE" ]; then
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echo "SUCCESS: Configuration changed and service restarted."
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else
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echo "FAILURE: Configuration change failed to verify."
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fi
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else
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echo "Action cancelled by user."
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fi |