Sicherheit ist erstmal egal will ich gesagt haben. Erstmal muss es funktionieren und dann mache ich es sicher 
So mom muss mir ausgeben lassen...hm komisch
Ich habe den Eindruck, das es funktioniert mit Einloggen nur das ich von der index.php direkt zurück geleitet werde? 
Ich poste nochmal beide codes (index und login) der übersichtlichskeits halber
index.php
<span class="syntaxhtml"><br /><span class="syntaxdefault"><?php<br /><br /> </span><span class="syntaxcomment">/*---------------------------CMS beginnt--------------------------*/<br /></span><span class="syntaxdefault"> session_start</span><span class="syntaxkeyword">();<br /><br /></span><span class="syntaxdefault"> if</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $_SESSION</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'eingeloggt'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">!==</span><span class="syntaxdefault"> TRUE </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">{<br /></span><span class="syntaxdefault"> </span><span class="syntaxcomment">//nicht eingeloggt müssen die Seite verlassen<br /></span><span class="syntaxdefault"> header</span><span class="syntaxkeyword">(</span><span class="syntaxstring">'Location: http://localhost/in_development/p-schuster.sarkkan.de/cms/login.php'</span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault"> </span><span class="syntaxcomment">//muss immer angepasst werden; entweder XAMPP oder WWW<br /></span><span class="syntaxdefault"> die</span><span class="syntaxkeyword">();<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /></span><span class="syntaxdefault"> elseif</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $_GET</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'pageID'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">==</span><span class="syntaxdefault"> </span><span class="syntaxstring">""</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">{<br /></span><span class="syntaxdefault"> </span><span class="syntaxcomment">//eingeloggte dürfen auf seite bleiben<br /></span><span class="syntaxdefault"> header</span><span class="syntaxkeyword">(</span><span class="syntaxstring">'Location:'</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> $_SERVER</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'PHP_SELF'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> </span><span class="syntaxstring">'?pageID=1'</span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /><br /><br /><br /></span><span class="syntaxdefault">?><br /></span><!DOCTYPE html><br /><html><br /><br /><head><br /> <title>Administrationsbereich</title><br /><br /> <meta charset="UTF-8" /><br /> <link href="style.css" type="text/css" rel="stylesheet" /><br /> <link href="favicon.ico" type="image/x-icon" rel="shortcut icon" /><br /></head><br /><body><br /><br /> <nav><br /> <a href="<span class="syntaxdefault"><?php echo $_SERVER</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'PHP_SELF'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> </span><span class="syntaxstring">"?pageID=1"</span><span class="syntaxdefault"> ?></span>">Dateien bearbeiten</a><br /> <a href="<span class="syntaxdefault"><?php echo $_SERVER</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'PHP_SELF'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> </span><span class="syntaxstring">"?pageID=2"</span><span class="syntaxdefault"> ?></span>">Seite verwalten</a><br /> <a href="<span class="syntaxdefault"><?php echo $_SERVER</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'PHP_SELF'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> </span><span class="syntaxstring">"?pageID=3"</span><span class="syntaxdefault"> ?></span>">ausloggen</a><br /> </nav><br /><br /> <section><br /> <span class="syntaxdefault"><?php<br /><br /> include</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> </span><span class="syntaxstring">"include/"</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> $_GET</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'pageID'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> </span><span class="syntaxstring">".php"</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">);<br /><br /></span><span class="syntaxdefault"> ?><br /></span> </section><br /><br /></body><br /></html><br /></span>
login.php
<span class="syntaxhtml"><br /><span class="syntaxdefault"><?php<br /><br /> </span><span class="syntaxcomment">/*------datenbank zugriff-----*/<br /></span><span class="syntaxdefault"> include</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> </span><span class="syntaxstring">"include/db-zugriff_xampp.php"</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">);<br /><br /></span><span class="syntaxdefault"> $db_link </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> mysql_connect </span><span class="syntaxkeyword">(</span><span class="syntaxdefault">MYSQL_HOST</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> MYSQL_BENUTZER</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> MYSQL_KENNWORT</span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault"> $db_sel </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> mysql_select_db</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> MYSQL_DATENBANK </span><span class="syntaxkeyword">)</span><span class="syntaxdefault"> OR die</span><span class="syntaxkeyword">(</span><span class="syntaxstring">"Auswahl der Datenbank fehlgeschlagen"</span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault"> $SQL </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> </span><span class="syntaxstring">"SELECT * FROM `logindaten`;"</span><span class="syntaxkeyword">;<br /></span><span class="syntaxdefault"> $db_erg </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> mysql_query</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $SQL </span><span class="syntaxkeyword">);<br /><br /></span><span class="syntaxdefault"> if </span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">!</span><span class="syntaxdefault"> $db_erg </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">{<br /></span><span class="syntaxdefault"> die</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> </span><span class="syntaxstring">'Ungültige Abfrage: '</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">.</span><span class="syntaxdefault"> mysql_error</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">)</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /><br /></span><span class="syntaxdefault"> $zeile </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> mysql_fetch_array</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $db_erg</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> MYSQL_ASSOC</span><span class="syntaxkeyword">);<br /><br /><br /><br /></span><span class="syntaxdefault"> </span><span class="syntaxcomment">/*-----------LOGIN-SCRIPT------------*/<br /><br /></span><span class="syntaxdefault"> </span><span class="syntaxcomment">//session wurde hier schon auf der index gestartet<br /><br /></span><span class="syntaxdefault"> if</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $_POST</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'Button'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">!=</span><span class="syntaxdefault"> </span><span class="syntaxstring">""</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">{<br /><br /></span><span class="syntaxdefault"> if</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $_POST</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'Benutzername'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">!=</span><span class="syntaxdefault"> </span><span class="syntaxstring">""</span><span class="syntaxdefault"> AND $_POST</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'Passwort'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">!=</span><span class="syntaxdefault"> </span><span class="syntaxstring">""</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault"> </span><span class="syntaxcomment">//wenn beides ausgefüllt ist<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">{<br /></span><span class="syntaxdefault"> $Benutzername </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> $_POST</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'Benutzername'</span><span class="syntaxkeyword">];<br /></span><span class="syntaxdefault"> $Passwort </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> $_POST</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'Passwort'</span><span class="syntaxkeyword">];<br /></span><span class="syntaxdefault"> $Passwort </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> md5</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">$Passwort</span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /><br /></span><span class="syntaxdefault"> if</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $Benutzername </span><span class="syntaxkeyword">==</span><span class="syntaxdefault"> $zeile</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'Benutzername'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> AND $Passwort </span><span class="syntaxkeyword">==</span><span class="syntaxdefault"> $zeile</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'Passwort'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">{<br /></span><span class="syntaxdefault"> $_SESSION</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'eingeloggt'</span><span class="syntaxkeyword">]</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> TRUE</span><span class="syntaxkeyword">;<br /></span><span class="syntaxdefault"> header</span><span class="syntaxkeyword">(</span><span class="syntaxstring">'Location: http://localhost/in_development/p-schuster.sarkkan.de/cms/index.php'</span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault"> die</span><span class="syntaxkeyword">();<br /></span><span class="syntaxdefault"> </span><span class="syntaxcomment">//muss immer angepasst werden; entweder XAMPP oder WWW<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /></span><span class="syntaxdefault"> else<br /> </span><span class="syntaxkeyword">{<br /></span><span class="syntaxdefault"> echo </span><span class="syntaxstring">"Falsche angaben"</span><span class="syntaxkeyword">;<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /></span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /><br /></span><span class="syntaxdefault"> mysql_free_result</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> $db_erg </span><span class="syntaxkeyword">);<br /></span><span class="syntaxdefault">?><br /></span><form action="<span class="syntaxdefault"><?php echo $_SERVER</span><span class="syntaxkeyword">[</span><span class="syntaxstring">'PHP_SELF'</span><span class="syntaxkeyword">];</span><span class="syntaxdefault"> ?></span>" method="post"><br /> <fieldset><br /> <legend>Einloggformular</legend><br /> <input type="text" name="Benutzername" id="Benutzername" /><br /> <input type="password" name="Passwort" id="Passwort" /><br /> <input type="submit" name="Button" /><br /> </fieldset><br /></form><br /></span>
PS: Das dynamische funktioniert; wollt ich nur mal gesagt haben