TCP/IP, Part 1

<body background="../../../images/top.png" bgcolor="#FFFFFF"> <table width="100%" cellspacing="0" cellpadding="0" summary=""> <tr> <td align="left" valign="top" rowspan="2" width="99%"><img src="../../../images/toptext_Johannes-Linux-talks.png" alt= "Johannes Linux talks" width="348" height="53" /></td> <td rowspan="2" align="center" valign="bottom"><img src="../../../images/dieseseite.en.png" alt="This page:" width="59" height="19" /></td> <td rowspan="2"><img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border="0" /></td> <td align="center" valign="top"><a href="tcpip1_inhalt.en.html" target="_parent"><img src="../../../images/empty.png" alt="no frames" border="0" width="23" height="30" /></a></td> <td rowspan="2"><img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border="0" /></td> <td align="center" valign="top"> <div title="Size: 821 kB"><a href="tcpip1.en.pdf" target="_blank"><img src="../../../images/pdffile.png" alt="-->" border="0" width="30" height="30" /></a></div> </td> <td rowspan="2"><img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border="0" /></td> <td align="center" valign="top"><a href="tcpip1.de.html" target="_top"><img src="../../../images/germanflag.png" alt= "-->" border="0" width="27" height="23" /></a></td> </tr> <tr> <td align="center" valign="bottom"><script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script> <script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script> <a href="tcpip1_inhalt.en.html" target="_parent" onmouseover= "ro_imgOver('ro_img_unknown1', 'without frameset'); return true" onmouseout= "ro_imgNormal('ro_img_unknown1'); return true" onfocus="ro_imgOver('ro_img_unknown1', 'without frameset'); return true" onblur="ro_imgNormal('ro_img_unknown1'); return true"><img name="ro_img_unknown1" src= "../../../images/noframes-std.en.png" alt="without frameset" width="95" height="19" border="0" /></a></td> <td align="center" valign="bottom"> <div title="Size: 821 kB"><script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script> <a href="tcpip1.en.pdf" target="_blank" onmouseover= "ro_imgOver('ro_img_unknown2', 'save as PDF'); return true" onmouseout="ro_imgNormal('ro_img_unknown2'); return true" onfocus="ro_imgOver('ro_img_unknown2', 'save as PDF'); return true" onblur= "ro_imgNormal('ro_img_unknown2'); return true"><img name="ro_img_unknown2" src="../../../images/PDF-std.en.png" alt= "save as PDF" width="71" height="19" border="0" /></a></div> </td> <td align="center" valign="bottom"><script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script> <a href="tcpip1.de.html" target="_top" onmouseover= "ro_imgOver('ro_img_unknown3', 'auf Deutsch'); return true" onmouseout="ro_imgNormal('ro_img_unknown3'); return true" onfocus="ro_imgOver('ro_img_unknown3', 'auf Deutsch'); return true" onblur= "ro_imgNormal('ro_img_unknown3'); return true"><img name="ro_img_unknown3" src="../../../images/Sprache-std.en.png" alt="auf Deutsch" width="69" height="19" border="0" /></a></td> </tr> </table>  <div align="center"> <h1 class="subject">TCP/IP<br /> Teil 1: Theoretische Grundlagen</h1> </div> <br /> <p align="center"><strong>Johannes Franken<br /></strong><kbd><jfranken@jfranken.de></kbd></p> <br /> <br /> <br /> <table summary=""> <tr> <td bgcolor="#FFAAAA" class="border"><strong>Caution:</strong><br /> Please note: This document is available in german only. An english translation for this document is in progress</td> </tr> </table>  <h1>Kursinhalt ,,Theoretische Grundlagen``</h1> <ul> <li><a href="#Kapitel1">Kapitel 1: Der TCP/IP Protocol Stack</a> <ul> <li>Einführung in Protokolle und Protocol Stacks</li> <li>Aufbau von TCP/IP</li> </ul> </li> <li><a href="#Kapitel2">Kapitel 2: Link-, Network- und Transport- Layer</a> <ul> <li>Beschreibung der kernelnahen Layer</li> <li>Netz-Hardware</li> </ul> </li> <li><a href="#Kapitel3">Kapitel 3: Application Layer</a> <ul> <li>Das Domain Name System</li> <li>Darstellung einiger Anwendungsprotokolle</li> </ul> </li> <li><a href="#Kapitel4">Kapitel 4: Fachliteratur</a> <ul> <li>Fachliteratur</li> </ul> </li> <li><a href="#Kapitel5">Kapitel 5: Diskussion</a> <ul> <li>Fragen/ Vorschläge zum 2.Teil/ Feedback</li> </ul> </li> </ul>  <h1><a name="Kapitel1">Kapitel 1: Der TCP/IP Protocol Stack</a></h1> <h2>Wer oder was ist TCP/IP</h2> TCP/IP bezeichnet einen <em>Protocol Stack</em>, der die <em>Protokolle</em> TCP<a name="tex2html1" target="fussnote" href="tcpip1/footnode.html#foot42">*</a> und IP<a name="tex2html2" target="fussnote" href= "tcpip1/footnode.html#foot43">*</a> verwendet. Er <ul> <li>entstand etwa 1968 aus dem ARPA<a name="tex2html3" target="fussnote" href="tcpip1/footnode.html#foot45">*</a> net-Projekt des US Verteidigungsministeriums.</li> <li>wurde zum Aufbau des heutigen Internet verwendet.</li> <li>wird heute in vielen Firmen eingesetzt, z.B. anstelle von IPX, Netbeui oder SNA. <ul> <li>um eigene Dienste im Internet anzubieten</li> <li>um fremde Dienste aus dem Internet im Firmennetz anzuwenden</li> <li>weil es gut dokumentiert ist</li> <li>weil es lizenzfrei eingesetzt werden darf</li> <li>weil es offensichtlich hervorragend funktioniert</li> </ul> </li> </ul>  <h2>Beispiel Protokolle</h2> Ein Protkoll ist die exakte Beschreibung eines Vorgangs.<br /> <div align="center"><img src="tcpip1/protokoll.png" alt="" width="640" height="1197" /></div>  <h2>Protocol Stacks</h2> Ein Protocol Stack ordnet Protokolle in Layer.<br /> <div align="center"><img src="tcpip1/philosoph.png" alt="" width="613" height="446" /><br /> (Beispiel aus Tanenbaum, Computer Networks)</div> <br /> Ziel ist die Austauschbarkeit der Protokolle innerhalb eines Layer ohne Beeinflussung der übrigen Layer.  <h2>Populäre Protocol Stacks</h2> <br /> In Reihenfolge ihrer Entstehung:<br /> <ol> <li>SNA<a name="tex2html5" target="fussnote" href="tcpip1/footnode.html#foot63">*</a> von IBM: sieben Layer, rechtlich geschützt</li> <li>TCP/IP: etwa vier Layer (Grenzen verschwommen), Protokolle verschiedener Schichten voneinander abhängig, aber erfolgreich</li> <li>IPX/SPX von Novell: vier Layer, Konzept von XNS<a name="tex2html6" target="fussnote" href= "tcpip1/footnode.html#foot65">*</a> übernommen</li> <li>OSI<a name="tex2html7" target="fussnote" href="tcpip1/footnode.html#foot67">*</a> von ISO<a name="tex2html8" target="fussnote" href="tcpip1/footnode.html#foot68">*</a>: sieben Layer, frei und perfekt aber zu spät</li> </ol>  <h2>Layer im ISO/OSI Protocol Stack</h2> <br /> <div align="center"><img src="tcpip1/isoosi.png" alt="" width="640" height="225" /></div>  <h2>Layer im TCP/IP Protocol Stack</h2> <br /> <div align="center"><img src="tcpip1/tcpip.png" alt="" width="640" height="226" /></div>  <h2>Zoom into TCP/IP Protocol Stack</h2> <br /> <div align="center"><img src="tcpip1/protokoll_stack_tcpip.png" alt="" width="640" height="376" /></div> <br />  <h2>Wichtige Erkenntnisse</h2> <br /> <ol> <li>Netscape merkt nicht, ob eine 3COM- oder iNTEL-Netzkarte oder ein Modem für die Verbindung sorgt; denn <ul> <li>der Unterschied betrifft nur den Link Layer, aber</li> <li>Netscape arbeitet im Application Layer.</li> </ul> </li> <li>Protocol Stacks sind praktisch.</li> <li>Der TCP/IP Protocol Stack eignet sich hervorragend für die Kommunikation zwischen gleichen und unterschiedlichen Architekturen.</li> </ol> <br /> kurze Pause...  <h1><a name="Kapitel2">Kapitel 2: Link-, Network- und Transport- Layer</a></h1> <h2>Media Layer</h2> <br /> Der Media Layer stellt die physikalische Verbindung zwischen zwei Punkten mittels Kupfer, Glasfaser, Laserstrecke, Infrarotblitz, Richtfunk etc her.<br /> <div align="center"><img src="tcpip1/layer0.png" alt="" width="640" height="517" /></div>  <h2>Media Layer: Patchfeld</h2> <br /> <div align="center">Das Patchfeld erleichtert Veränderungen an der Verkabelung. <table cellpadding="3" summary=""> <tr> <td align="left">Vorderansicht</td> <td align="right">Rückansicht</td> </tr> <tr> <td align="left"><img src="tcpip1/patchfeldvorne.jpg" alt="" width="320" height="240" /></td> <td align="right"><img src="tcpip1/patchfeldhinten.jpg" alt="" width="320" height="240" /></td> </tr> </table> </div>  <h2>Link Layer</h2> <br /> Der Link Layer besteht aus zwei Sub-Layers mit folgenden Aufgaben:<br /> <ul> <li>Low Level: Hardware, die Frames in Signale umsetzt und eine <em>Topologie</em> erwartet. (z.B. <em>Modem</em><a name="tex2html9" target="fussnote" href="tcpip1/footnode.html#foot105">*</a>, <em>NIC</em><a name= "tex2html10" target="fussnote" href="tcpip1/footnode.html#foot107">*</a>). Erkennt ggf. Leitungsschäden oder Kollisionen.</li> <li>Hi Level (am Beispiel <em>Ethernet</em>:) <ul> <li>alle Sendungen in Frames teilen und CRC<a name="tex2html11" target="fussnote" href= "tcpip1/footnode.html#foot110">*</a> anhängen.</li> <li>eindeutige Empfänger- und Absender-ID mitsenden (MAC<a name="tex2html12" target="fussnote" href= "tcpip1/footnode.html#foot111">*</a>-Adresse)</li> <li>Ein Protokoll zum Aufsetzen des Network Layer anbieten</li> </ul> </li> </ul>  <h2>Low Level Link Layer: Topologie</h2> <br /> <div align="center"><img src="tcpip1/topologien.png" alt="" width="640" height="353" /></div>  <h2>Low Level Link Layer: NIC, Modem, ISDN Adapter</h2> <br /> Hardware, die den Computer mit dem Netz verbindet.<br /> <div align="center"> <table cellpadding="3" summary=""> <tr> <td align="center">NIC</td> <td align="center">MODEM</td> </tr> <tr> <td align="center"><img src="tcpip1/3com_nic.jpg" alt="" width="320" height="271" /></td> <td align="center"><br /> <img src="tcpip1/3com_modem.jpg" alt="" width="320" height="184" /></td> </tr> </table> </div>  <h2>Low Level Link Layer: Hub, Concentrator, Repeater</h2> <br /> Der Hub leitet alle Frames an die jeweils anderen Ports weiter.<br /> Es gibt zwei Arten von Hubs: <ul> <li>Passive Hub = Concentrator: Luxus Lüsterklemme.</li> <li>Active Hub = Repeater: verstärkt die Signale entweder analog oder digital.</li> </ul> <br /> <div align="center"><img src="tcpip1/3com_hub.jpg" alt="" width="320" height="118" /></div>  <h2>Hi Level Link Layer: Spezifikation Ethernet-Frame</h2> <br /> <div align="center"><img src="tcpip1/ethernet.png" alt="" width="640" height="202" /></div> <br /> Weitere mögliche Protokolle: z.B. PPP<a name="tex2html13" target="fussnote" href= "tcpip1/footnode.html#foot137">*</a>, SLIP<a name="tex2html14" target="fussnote" href= "tcpip1/footnode.html#foot138">*</a>, IEEE<a name="tex2html15" target="fussnote" href= "tcpip1/footnode.html#foot139">*</a> 802.2 und 802.3, je nach verwendeter Hardware.  <h2>Hi Level Link Layer: Switch, Bridge</h2> <br /> Bestimmen den Ausgangsport anhand der MAC-Adressen.<br /> Im Gegensatz zum Switch wandelt die Bridge zusätzlich verschiedene Low Level-Protokolle ineinander um. (z.B. von 100baseT auf Token Ring).<br /> <div align="center"> <table cellpadding="3" summary=""> <tr> <td align="left"><img src="tcpip1/layer2.png" alt="" width="640" height="289" /></td> <td align="right"><br /> <img src="tcpip1/3com_switch.jpg" alt="" width="320" height="114" /></td> </tr> </table> </div>  <h2>Network Layer</h2> <br /> Das typische Network-Layer Protokoll des TCP/IP Stack ist das IP in Version 4.<br /> <div align="center"><img src="tcpip1/ip.png" alt="" width="640" height="260" /></div>  <h2>Network Layer: Routing</h2> <br /> Der Network Layer implementiert das Routing.<br /> <div align="center"> <table cellpadding="3" summary=""> <tr> <td align="left"><img src="tcpip1/routing.png" alt="" width="640" height="445" /></td> <td align="right"><br /> <img src="tcpip1/3com_router.jpg" alt="" width="320" height="136" /></td> </tr> <tr> <td align="left"> </td> <td align="right">IP-Router</td> </tr> </table> </div>  <h2>Network Layer: Router</h2> <br /> <div align="center"><img src="tcpip1/layer3.png" alt="" width="640" height="289" /></div> <br /> ,,Na und, das können Hubs oder Switches auf Link Ebene doch auch...?``  <h2>Network Layer: Hubs und Switches sind keine Router</h2> <br /> ,,Das können Hubs oder Switches auf Link Ebene doch auch...?``<br /> Theoretisch: ja.<br /> Aber in der Praxis: kaum möglich.<br /> Der ausschließliche Einsatz von Hubs oder Switches hätte in einem großen Netz wie z.B. dem Internet, folgende Nachteile: <ul> <li>alle Switches müssten vorher lernen, wo welche MAC-Adresse erreichbar ist.</li> <li>Hubs würden das Netz mit unnötigen Frames fluten und Kapazität verschwenden</li> </ul>  <h2>Network Layer: IP-Adresse</h2> <br /> Jede Netzschnittstelle erhält <ul> <li>eine eindeutige 32bit IP-Adresse (zusätzlich zur 48 bit MAC-Adresse),</li> <li>eine <em>Routing Tabelle</em></li> </ul> <br /> Zur besseren Lesbarkeit notiert man die IP-Adresse als dezimale Bytes.<br /> Bytes können Werte zwischen 0 und 255 annehmen.<br /> Beispiel: aus <tt>11000000101010000010101000001100</tt> wird <tt>192.168.42.12</tt><br /> Wie lautet die Dezimaldarstellung der IP-Adresse <tt>10001101000000100000000100000001</tt>?  <h2>Network Layer: Routing Tabelle</h2> <br /> Die Routing Tabelle einer Netzschnittstelle enthält pro Zeile folgende Einträge:<br /> <ul> <li>Ziel-Adresse: Eine fremde IP-Adresse.</li> <li>Gateway-Adresse: IP-Adresse eines Routers, über den man zur Zieladresse gelangt.</li> <li><em>Netzmaske</em> (32 bits): gibt an, welche Bits eines Empfängers mit der Ziel-Adresse übereinstimmen müssen, damit ein IP Datagram über diesen Gateway geleitet wird.</li> </ul> <br /> Beispiel: <table cellpadding="3" border="1" summary=""> <tr> <td align="left">Ziel</td> <td align="left">Gateway</td> <td align="left">Netzmaske</td> </tr> <tr> <td align="left"><tt>192.168.42.0</tt></td> <td align="left"><tt>0.0.0.0</tt></td> <td align="left"><tt>255.255.255.0</tt></td> </tr> <tr> <td align="left"><tt>10.0.0.0</tt></td> <td align="left"><tt>192.168.42.19</tt></td> <td align="left"><tt>255.0.0.0</tt></td> </tr> <tr> <td align="left"><tt>0.0.0.0</tt></td> <td align="left"><tt>192.168.42.1</tt></td> <td align="left"><tt>0.0.0.0</tt></td> </tr> </table>  <h2>Network Layer: Routing Tabelle Beispiel</h2> <br /> <div align="center"><img src="tcpip1/routing-tabelle.png" alt="" width="640" height="232" /><br /> <br /> <br /> <br /> Routing Tabelle von <tt>192.168.42.10</tt>: <table cellpadding="3" border="1" summary=""> <tr> <td align="left">Ziel</td> <td align="left">Gateway</td> <td align="left">Netzmaske</td> </tr> <tr> <td align="left"><tt>192.168.42.0</tt></td> <td align="left"><tt>0.0.0.0</tt></td> <td align="left"><tt>255.255.255.0</tt></td> </tr> <tr> <td align="left"><tt>10.0.0.0</tt></td> <td align="left"><tt>192.168.42.19</tt></td> <td align="left"><tt>255.0.0.0</tt></td> </tr> <tr> <td align="left"><tt>0.0.0.0</tt></td> <td align="left"><tt>192.168.42.1</tt></td> <td align="left"><tt>0.0.0.0</tt></td> </tr> </table> </div>  <h2>Network Layer: Routing-Tabelle : Netzmaske</h2> <br /> Die Bits der IP-Adresse, an deren Position die Netzmaske 1 ist, bilden die Netzadresse, der Rest den Hostpart. Beispiele: <ul> <li>255.255.255.255 für Hostrouting,</li> <li>255.255.255.0 für Routing in Klasse C Netze</li> <li>255.255.0.0 für Routing in Klasse B Netze</li> <li>255.0.0.0 für Klasse A Netze</li> <li>0.0.0.0 für default route</li> </ul> <br /> <div align="center"><img src="tcpip1/netzmaske.png" alt="" width="640" height="213" /><br /> <br /> <br /> <br /></div> <br /> Wenn die Netzmaske andere Werte als 0 und 255 enthält, sagt man Sub-Netz und Subnetzmaske statt Netz und Netzmaske.  <h2>Network Layer: Konventionen zu IP-Adressen im Internet</h2> <br /> zur Teilnahme von IP-Adressen am Internet gibt es folgende Regeln: <ul> <li>Klasse A: IP beginnt mit Bit <tt>0</tt> IP-Adressen von <tt>0.0.0.0</tt> bis <tt>127.255.255.255</tt></li> <li>Klasse B: IP beginnt mit Bits <tt>10</tt> IP-Adressen von <tt>128.0.0.0</tt> bis <tt>191.255.255.255</tt></li> <li>Klasse C: IP beginnt mit Bits <tt>110</tt> IP-Adressen von <tt>192.0.0.0</tt> bis <tt>223.255.255.255</tt></li> </ul> <br /> Zusätzlich sind die IP-Adressen <tt>10.*.*.*, 172.16.*.*-172.31.*.* und 192.168.*.*</tt> für private Netze reserviert und im Internet verboten. (Quelle: RFC1597<a name="tex2html16" target="fussnote" href= "tcpip1/footnode.html#foot231">*</a>)<br /> Wieso?  <h2>Network Layer: Diagnosetools <tt>ping</tt> und <tt>traceroute</tt></h2> <div align="center"><img src="tcpip1/ping.png" alt="" width="640" height="193" /></div> <br /> <div align="center"><img src="tcpip1/traceroute.png" alt="" width="640" height="221" /></div>  <h2>Transport Layer</h2> IP hat zwei Probleme: <ul> <li>Die Daten sind nicht geprüft (außer ggf. der 4 bit Ethernet-Frame-CRC).</li> <li><tt>192.168.42.1</tt> weiß nicht, ob er die Daten an das Webserverprogramm oder das Fileserverprogramm leiten soll:<br /> <div align="center"><img src="tcpip1/ohneports.png" alt="" width="640" height="212" /><br /></div> </li> </ul>  <h2>Transport Layer: Ports</h2> <div align="center"><img src="tcpip1/mitports.png" alt="" width="640" height="236" /><br /></div>  <h2>Transport Layer: UDP</h2> <div align="center"><img src="tcpip1/udp.png" alt="" width="640" height="202" /><br /></div> UDP Datagram  <h2>Transport Layer: UDP Nachteile</h2> In einigen Anwendungen (z.B. telnet, ftp) hätte UDP gravierende Nachteile, weil <ul> <li>die Verbindung nach erfolgter Sendung (z.B. eines Tastendrucks) abbricht und</li> <li>keine Bestätigung des Erhalts vorgesehen ist.</li> </ul> <br /> Ideen zur Lösung?  <h2>Transport Layer: TCP</h2> TCP bietet die verlässliche, sitzungsorienterte Übertragung beliebig langer Nachrichten. <div align="center"><img src="tcpip1/tcp.png" alt="" width="640" height="202" /><br /></div> Pause...  <h1><a name="Kapitel3">Kapitel 3: Application Layer</a></h1> <h2>Hostnames</h2> <br /> Zur Vereinfachung kann man <ul> <li>jeder IP-Adresse einen oder mehrere Hostnamen zuordnen (z.B. <tt>www</tt>)</li> <li>jedem Hostname einen Domainnamen zuordnen (z.B. <tt>lufthansa.de</tt>)</li> </ul> Die Darstellung Hostname.Domainname heißt FQDN<a name="tex2html17" target="fussnote" href= "tcpip1/footnode.html#foot267">*</a>.<br /> Beispiel: <div align="center"><img src="tcpip1/hostnames.png" alt="" width="640" height="209" /><br /></div> <br />  <h2>Hosts Resolving</h2> <br /> Zur Erstellung eines TCP-Segments oder einer UDP-Message wird die IP-Adresse benötigt.<br /> Daher haben Anwendungen die Aufgabe, die IP-Adresse aus dem Hostname zu ermitteln. Dieser Vorgang heißt Auflösung oder resolving.<br /> Typische Vorgehensweisen hierbei sind die <em>Hosts</em>- und die <em>DNS</em>-Methode.<br /> Hosts Methode:<br /> <div align="center"><img src="tcpip1/resolve1.png" alt="" width="640" height="123" /></div>  <h2>DNS Resolving</h2> <br /> Der Nameserver ist ein Programm auf einem Netzrechner. Über das DNS<a name="tex2html18" target="fussnote" href= "tcpip1/footnode.html#foot278">*</a>-Protokoll bietet es anderen Netzteilnehmern auf Port 53 <ul> <li>die IP-Adresse zu einem Hostname (forward mapping)</li> <li>die Hostnamen zu einer IP-Adresse (reverse mapping, pointer queries)</li> <li>die Weiterleitung der Auflösung an andere Nameserver (forwarding)</li> </ul> <br /> <div align="center"><img src="tcpip1/resolve2.png" alt="" width="640" height="242" /></div>  <h2>Well known ports</h2> <br /> <div align="center"> <table cellpadding="3" border="1" summary=""> <tr> <th align="left"><font size="-1">Protokoll</font></th> <th align="right"><font size="-1">Port</font></th> </tr> <tr> <td align="left"><font size="-1">telnet</font></td> <td align="right"><font size="-1">23</font></td> </tr> <tr> <td align="left"><font size="-1">daytime</font></td> <td align="right"><font size="-1">13</font></td> </tr> <tr> <td align="left"><font size="-1">smtp</font></td> <td align="right"><font size="-1">25</font></td> </tr> <tr> <td align="left"><font size="-1">http</font></td> <td align="right"><font size="-1">80</font></td> </tr> <tr> <td align="left"><font size="-1">ftp</font></td> <td align="right"><font size="-1">21</font></td> </tr> <tr> <td align="left"><font size="-1">dns</font></td> <td align="right"><font size="-1">53</font></td> </tr> <tr> <td align="left"><font size="-1">https</font></td> <td align="right"><font size="-1">443</font></td> </tr> <tr> <td align="left"><font size="-1">pop3</font></td> <td align="right"><font size="-1">110</font></td> </tr> <tr> <td align="left"><font size="-1">imap2</font></td> <td align="right"><font size="-1">143</font></td> </tr> <tr> <td align="left"><font size="-1">netbios-ns</font></td> <td align="right"><font size="-1">137</font></td> </tr> <tr> <td align="left"><font size="-1">netbios-ssn</font></td> <td align="right"><font size="-1">139</font></td> </tr> <tr> <td align="left"><font size="-1">snmp</font></td> <td align="right"><font size="-1">161</font></td> </tr> <tr> <td align="left"><font size="-1">printer</font></td> <td align="right"><font size="-1">515</font></td> </tr> <tr> <td align="left"><font size="-1">ircd</font></td> <td align="right"><font size="-1">6667</font></td> </tr> <tr> <td align="left"><font size="-1">oracle</font></td> <td align="right"><font size="-1">1521</font></td> </tr> </table> </div> Die Umsetzung von Portnamen in Portnummern erledigt die <tt>services</tt>-Datei.  <h2>telnet</h2> <br /> <div align="center"><img src="tcpip1/telnet2.png" alt="" width="640" height="138" /></div>  <h2>daytime</h2> <br /> <div align="center"><img src="tcpip1/daytime2.png" alt="" width="640" height="194" /></div>  <h2>smtp</h2> <br /> <div align="center"><img src="tcpip1/smtp2.png" alt="" width="640" height="324" /></div>  <h2>smtp</h2> <br /> <div align="center"><img src="tcpip1/smtp3.png" alt="" width="640" height="703" /></div>  <h2>http</h2> <br /> <div align="center"><img src="tcpip1/http2.png" alt="" width="640" height="314" /></div>  <h2>http</h2> <br /> <div align="center"><img src="tcpip1/http3.png" alt="" width="640" height="406" /></div>  <h2>ftp</h2> <br /> <div align="center"><img src="tcpip1/ftp2.png" alt="" width="640" height="217" /></div>  <h1><a name="Kapitel4">Kapitel 4: Fachliteratur</a></h1> <h2>Fachliteratur</h2> <ul> <li>die RFCs (stets aktuell auf <tt>http://www.rfc-editor.org/</tt>)</li> <li>Andrew S. Tanenbaum, <em>Computer Networks</em>, Prentice Hall</li> <li>W. Richard Stevens, <em>Unix Network Programming</em>, Prentice Hall</li> <li>W. Richard Stevens, <em>TCP/IP Illustrated, Volume 1 und 3</em>, Addison-Wesley</li> <li>Paul Albitz & Cricket Liu, <em>DNS and BIND</em>, O'Reilly</li> <li>Johannes Franken, <em>DNS & BIND GE-PACKT</em>, MITP</li> <li>Anatol Badach, <em>Datenkommunikation mit ISDN</em>, International Thomson Publishing</li> <li>Oxford University Press, <em>Computer Lexikon</em>, Sybex</li> </ul> <div class="noprint"> <hr /> <table width="100%" summary=""> <tr> <td align="left" valign="middle"><font size="-2">$Id: tcpip1.wml,v 1.17 2009-09-22 07:26:14 jfranken Exp $ <a href= "tcpip1.log.html">[ChangeLog]</a><br /> $Id: template.inc,v 1.81 2009-09-07 19:26:07 jfranken Exp $ <a href="../../../template.log.html">[ChangeLog]</a><br /> © Johannes Franken. <a href="../../../impressum/rechtliches.en.html" target="_parent">Imprint and disclaimer</a></font></td> <td align="right" valign="middle"><a href="http://validator.w3.org/check/referer" target="w3c"><img border="0" src= "../../../images/valid-xhtml10.png" alt="Valid XHTML 1.0!" width="88" height="31" /></a></td> </tr> </table> </div> <hr /> <h1>Navigation:</h1> <font size="1"><script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script> <script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script> <a href="../../../startseite.en.html" target="_top" onmouseover= "nb_imgOver('nb_img1_startseite', 0, ''); 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return true" onmouseout="nb_imgNormal('nb_img1_j_fotos'); return true" onfocus= "nb_imgOver('nb_img1_j_fotos', 0, ''); return true" onblur="nb_imgNormal('nb_img1_j_fotos'); return true"><img name= "nb_img1_j_fotos" src="../../../images/j_fotos-std.en.png" border="0" alt="Photos" width="60" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border= "0" /><a href="../../../homepages/johannes/leisure.en.html" target="_top" onmouseover= "nb_imgOver('nb_img1_leisure', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_leisure'); return true" onfocus= "nb_imgOver('nb_img1_leisure', 0, ''); return true" onblur="nb_imgNormal('nb_img1_leisure'); return true"><img name= "nb_img1_leisure" src="../../../images/leisure-std.en.png" border="0" alt="Leisure" width="58" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border= "0" /><a href="../../../homepages/johannes/j_humor.en.html" target="_top" onmouseover= "nb_imgOver('nb_img1_j_humor', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_j_humor'); return true" onfocus= "nb_imgOver('nb_img1_j_humor', 0, ''); return true" onblur="nb_imgNormal('nb_img1_j_humor'); return true"><img name= "nb_img1_j_humor" src="../../../images/j_humor-std.en.png" border="0" alt="Humor" width="60" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border= "0" /><a href="../../../homepages/johannes/kenntnisse.en.html" target="_top" onmouseover= "nb_imgOver('nb_img1_kenntnisse', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_kenntnisse'); return true" onfocus="nb_imgOver('nb_img1_kenntnisse', 0, ''); return true" onblur= "nb_imgNormal('nb_img1_kenntnisse'); return true"><img name="nb_img1_kenntnisse" src= "../../../images/kenntnisse-std.en.png" border="0" alt="Experiences" width="97" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border= "0" /><a href="../../../homepages/johannes/j_lebenslauf.en.html" target="_top" onmouseover= "nb_imgOver('nb_img1_j_lebenslauf', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_j_lebenslauf'); return true" onfocus="nb_imgOver('nb_img1_j_lebenslauf', 0, ''); return true" onblur= "nb_imgNormal('nb_img1_j_lebenslauf'); return true"><img name="nb_img1_j_lebenslauf" src= "../../../images/j_lebenslauf-std.en.png" border="0" alt="Vitae" width="45" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border= "0" /><a href="../../../homepages/johannes/j_wunschliste.en.html" target="_top" onmouseover= "nb_imgOver('nb_img1_j_wunschliste', 0, ''); return true" onmouseout= "nb_imgNormal('nb_img1_j_wunschliste'); return true" onfocus="nb_imgOver('nb_img1_j_wunschliste', 0, ''); return true" onblur="nb_imgNormal('nb_img1_j_wunschliste'); return true"><img name="nb_img1_j_wunschliste" src= "../../../images/j_wunschliste-std.en.png" border="0" alt="Wishlist" width="64" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt="  " width="20" height="1" align="bottom" border= "0" /><a href="../../../homepages/johannes/j_pgp.en.html" target="_top" onmouseover= "nb_imgOver('nb_img1_j_pgp', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_j_pgp'); return true" onfocus= "nb_imgOver('nb_img1_j_pgp', 0, ''); return true" onblur="nb_imgNormal('nb_img1_j_pgp'); return true"><img name= "nb_img1_j_pgp" src="../../../images/j_pgp-std.en.png" border="0" alt="PGP" width="42" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt=" " width="10" height="1" align="bottom" border="0" /><a href= "../../../homepages/beate.en.html" target="_top" onmouseover="nb_imgOver('nb_img1_beate', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_beate'); return true" onfocus="nb_imgOver('nb_img1_beate', 0, ''); return true" onblur="nb_imgNormal('nb_img1_beate'); return true"><img name="nb_img1_beate" src="../../../images/beate-std.en.png" border="0" alt="Beate" width="51" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt=" " width="10" height="1" align="bottom" border="0" /><a href= "../../../homepages/sarah.en.html" target="_top" onmouseover="nb_imgOver('nb_img1_sarah', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_sarah'); return true" onfocus="nb_imgOver('nb_img1_sarah', 0, ''); return true" onblur="nb_imgNormal('nb_img1_sarah'); return true"><img name="nb_img1_sarah" src="../../../images/sarah-std.en.png" border="0" alt="Sarah" width="48" height="26" /></a><br /> <img src="../../../images/transparentpixel.png" alt=" " width="10" height="1" align="bottom" border="0" /><a href= "../../../homepages/hannah.en.html" target="_top" onmouseover="nb_imgOver('nb_img1_hannah', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_hannah'); return true" onfocus="nb_imgOver('nb_img1_hannah', 0, ''); return true" onblur="nb_imgNormal('nb_img1_hannah'); return true"><img name="nb_img1_hannah" src="../../../images/hannah-std.en.png" border="0" alt="Hannah" width="64" height="26" /></a><br /> <a href="../../../gaestebuch.en.html" target="_top" onmouseover="nb_imgOver('nb_img1_gaestebuch', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_gaestebuch'); return true" onfocus= "nb_imgOver('nb_img1_gaestebuch', 0, ''); return true" onblur= "nb_imgNormal('nb_img1_gaestebuch'); return true"><img name="nb_img1_gaestebuch" src= "../../../images/gaestebuch-std.en.png" border="0" alt="Guestbook" width="91" height="26" /></a><br /> <a href="../../../impressum.en.html" target="_top" onmouseover="nb_imgOver('nb_img1_impressum', 0, ''); return true" onmouseout="nb_imgNormal('nb_img1_impressum'); return true" onfocus= "nb_imgOver('nb_img1_impressum', 0, ''); return true" onblur= "nb_imgNormal('nb_img1_impressum'); return true"><img name="nb_img1_impressum" src= "../../../images/impressum-std.en.png" border="0" alt="About" width="54" height="26" /></a></font><br /> <br /> <br /> <form method="get" action="http://www.google.com/custom" target="jfrankeninhalt"><img src= "../../../images/transparentpixel.png" alt=" " width="190" height="2" align="bottom" border="0" /><br /> <img src="../../../images/transparentpixel.png" alt=" " width="8" height="1" align="bottom" border="0" /><img src= "../../../images/google16x16.png" alt="" width="16" height="19" /><img src="../../../images/transparentpixel.png" alt= " " width="8" height="1" align="bottom" border="0" /><input type="image" name="sa" value="Search" src= "../../../images/Suche.en.png" alt="Search:" /><br /> <img src="../../../images/transparentpixel.png" alt=" " width="32" height="1" align="bottom" border="0" /><input type= "text" name="q" size="10" maxlength="255" value="" style= "color:#ddddff;border-color:#ddddff;background:#112277" /><input type="hidden" name="cof" value= "T:000000;LW:540;ALC:112277;L:http://www.jfranken.de/images/toptext_FRANKEN--IT-CONCEPTS.png;LC:112277;LH:53;BGC:ffffff;AH:left;VLC:112277;AWFID:ec81011eb1f53f99;" /><input type="hidden" name="domains" value="www.jfranken.de" /><br /> <input type="hidden" name="sitesearch" value="www.jfranken.de" /></form> <script type="text/javascript" language="JavaScript"> //<![CDATA[ function ro_imgNormal(imgName) { if (document.images) { document[imgName].src = eval(imgName + '_n.src'); self.status = ''; } } function ro_imgOver(imgName, descript) { if (document.images) { document[imgName].src = eval(imgName + '_o.src'); self.status = descript; } } //]]> </script><br /> <img src="../../../images/transparentpixel.png" alt=" " width="190" height="2" align="bottom" border="0" /><br /> <img src="../../../images/transparentpixel.png" alt=" " width="8" height="1" align="bottom" border="0" /><img src= "../../../images/feed-icon-16x16.png" alt="" width="16" height="19" /><img src="../../../images/transparentpixel.png" alt=" " width="8" height="1" align="bottom" border="0" /><img src="../../../images/NewsFeeds.png" alt="NewsFeeds" width="67" height="19" /><br /> <img src="../../../images/transparentpixel.png" alt=" " width="32" height="1" align="bottom" border="0" /> <script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script><a href="http://www.jfranken.de/feed-rss2.en.xml" target="_blank" onmouseover= "ro_imgOver('ro_img_unknown4', 'RSS2-Feed'); return true" onmouseout="ro_imgNormal('ro_img_unknown4'); return true" onfocus="ro_imgOver('ro_img_unknown4', 'RSS2-Feed'); return true" onblur= "ro_imgNormal('ro_img_unknown4'); return true"><img name="ro_img_unknown4" src="../../../images/feed-rss2.png" alt= "RSS2-Feed" width="70" height="15" border="0" /></a><br /> <img src="../../../images/transparentpixel.png" alt=" " width="32" height="1" align="bottom" border="0" /> <script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script><a href="http://www.jfranken.de/feed-atom1.en.xml" target="_blank" onmouseover= "ro_imgOver('ro_img_unknown5', 'ATOM1-Feed'); return true" onmouseout="ro_imgNormal('ro_img_unknown5'); return true" onfocus="ro_imgOver('ro_img_unknown5', 'ATOM1-Feed'); return true" onblur= "ro_imgNormal('ro_img_unknown5'); return true"><img name="ro_img_unknown5" src="../../../images/feed-atom1.png" alt= "ATOM1-Feed" width="70" height="15" border="0" /></a><br /> <img src="../../../images/transparentpixel.png" alt=" " width="32" height="1" align="bottom" border="0" /> <script type="text/javascript" language="JavaScript"> //<![CDATA[  //]]> </script><a href="../../../impressum/feeds.en.html" target="_parent" onmouseover= "ro_imgOver('ro_img_unknown6', 'Subscribe'); return true" onmouseout="ro_imgNormal('ro_img_unknown6'); return true" onfocus="ro_imgOver('ro_img_unknown6', 'Subscribe'); return true" onblur= "ro_imgNormal('ro_img_unknown6'); return true"><img name="ro_img_unknown6" src="../../../images/Subscribe.en.png" alt= "Subscribe" width="65" height="19" border="0" /></a> </body>