C# Textdatei parsen, restrukturieren und ausgeben

                            if (sReader.ReadLine().StartsWith("# ") ||
                                sReader.ReadLine().StartsWith(" ") ||
                                char.IsLetter(sReader.ReadLine(), 0))
                            {
                                continue;
                            }

#region Using directives
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading.Tasks;
using System.Windows.Forms;

using System.Diagnostics;
#endregion

namespace ipFileParser
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length == 0)
            {
                MessageBox.Show("Programm über Befehlszeile mit Eingabedatei als Parameter starten!\n Beispiel: ipFileParser ips.txt", "Fehler", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
            }
            else
            {
                if ( File.Exists(args[0]) )
                {
                    List<String> input = new List<string>();
                    List<string> output = new List<string>();
                    using (StreamReader sReader = new StreamReader(args[0]))
                    {
#if DEBUG
                        int totLines = 0;
                        int numLines = 0;
                        string tmp;
#endif
                        string buf;
                        while ( sReader.Peek() >= 0)    //  still reading
                        {
#if DEBUG
                            totLines++;
#endif

                            if (sReader.ReadLine().StartsWith("# ") ||
                                sReader.ReadLine().StartsWith(" ") ||
                                char.IsLetter(sReader.ReadLine(), 0))
                            {
                                continue;
                            }
#if DEBUG 
                            numLines++;
#endif
                            buf = sReader.ReadLine();
                            if (buf.StartsWith("deny from "))
                            {
                                buf.Substring(0, 10);   //  remove "deny from "
                            }
                            output.Add(buf);
                        }

                        File.WriteAllLines(Application.StartupPath + "\\output.txt", output.ToArray());

#if DEBUG
                            tmp = string.Format("{0} lines read, {1} lines skipped, {2} lines pushed to output", totLines, totLines - numLines, numLines);
                            Debug.WriteLine(tmp);
#endif
                    }
                }
            }
        }
    }
}

                        while ( sReader.Peek() >= 0)    //  still reading
                        {
                            buf = sReader.ReadLine();
#if DEBUG
                            totLines++;
#endif

                            if (buf.Length > 0)
                            {
                                if (buf.StartsWith("# ") || buf.StartsWith(" ") || char.IsLetter(buf, 0))
                                {
                                    continue;
                                }
#if DEBUG 
                            numLines++;
#endif

                                if (buf.StartsWith("deny from "))
                                {
                                    buf.Substring(0, 10);   //  remove "deny from "
                                }
                                output.Add(buf); 
                            }
                        }

char.IsLetter(buf, 0)'

\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\/d{1,2}\b

Param(
    [ValidateScript({ Test-Path -PathType Leaf $_ })]
    [Parameter( Position = 0 )]
    [Alias('Input')]
    [string]$InputFilename,
    [Parameter( Position = 1 )]
    [Alias('Output')]
    [string]$OutputFilename
)

$Contents = @()

$IpRegex = "\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\/\d{1,2}\b"

switch -Regex -File $InputFilename
{
    '^(deny|allow) from\b'
    {
        switch( $_ )
        {
            {$_ -match $IpRegex} { ([Regex]$IpRegex).Matches( $_ ) | % { $Contents += $_.Value } }
            default { $Contents += $_ }
        }
    }
    '^#\$' { $Contents += $_ }
    '^$' { $Contents += $_ }
    # Whitelist anstatt ^[a-z]
    '^order' { $Contents += $_ }
}

if( ![string]::IsNullOrEmpty( $OutputFilename ) ) { $Contents > $OutputFilename }
else { $Contents }

script.ps1 input.txt
script.ps1 input.txt output.txt
script.ps1 input.txt > output.txt
script.ps1 -Input input.txt
script.ps1 -Input input.txt -Output output.txt
script.ps1 -InputFilename input.txt -OutputFilename output.txt 
// usw.

To also block Nigerian traffic copy/paste these deny statements after the order and allow statements in your .htaccess file:

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned