68 lines
4.2 KiB
HTML
68 lines
4.2 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="IP packet header" />
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<meta name="abstract" content="You can create filter rules to refer to various portions of IP, TCP, UDP, and ICMP headers." />
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<meta name="description" content="You can create filter rules to refer to various portions of IP, TCP, UDP, and ICMP headers." />
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<meta name="DC.Relation" scheme="URI" content="rzajbrzajb4bhidenat.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2000, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2000, 2006" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>IP packet header</title>
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</head>
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<body id="rzajb1b-header"><a name="rzajb1b-header"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">IP packet header</h1>
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<div><p>You can create filter rules to refer to various portions of IP,
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TCP, UDP, and ICMP headers.</p>
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<p>The following list includes the fields you refer to in a filter rule that
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make up the IP packet header: </p>
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<ul><li>Source IP address</li>
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<li>Protocol (for example, TCP, UDP)</li>
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<li>Destination IP address</li>
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<li>Source port</li>
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<li>Destination port</li>
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<li>IP datagram direction (inbound, outbound, or both)</li>
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<li>TCP SYN bit</li>
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</ul>
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<p>For example, you can create and activate a rule that filters a packet based
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on the destination IP address, source IP address, and direction (inbound).
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In this case, the system matches all incoming packets (according to their
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origin and destination addresses) with corresponding rules. Then the system
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takes the action that you specified in the rule. The system discards any packets
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that are <em>not</em> permitted in your filter rules. This is called the default
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deny rule.</p>
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<div class="note"><span class="notetitle">Note:</span> The system applies the default deny rule to packets only if the physical
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interface has at least one active rule. This rule can be customer-defined
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or generated by iSeries™ Navigator.
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Regardless of whether the filter rule permits inbound traffic or outbound
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traffic, the system implements the default deny rule in both directions. If
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there isn't a filter rule active on the physical interface, then the default
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deny rule will not work.</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzajbrzajb1afilter.htm" title="Though not a fully functional firewall in itself, packet rules provide a solid component that can filter packets for your iSeries server.">IP filtering</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzajbrzajb4bhidenat.htm" title="Masquerade (hide) network address translation (NAT) allows you to keep the outside world (outside the iSeries server) from knowing the actual address of a personal computer. NAT routes traffic from your personal computer to your iSeries server, which essentially makes the iSeries server the gateway for your personal computer.">Masquerade (hide) NAT</a></div>
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</div>
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</div>
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</body>
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</html>
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