86 lines
5.6 KiB
HTML
86 lines
5.6 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 http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Secure your TCP/IP environment" />
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<meta name="abstract" content="This topic provides general suggestions for steps that you can take to reduce the security exposures in the TCP/IP environment on your system." />
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<meta name="description" content="This topic provides general suggestions for steps that you can take to reduce the security exposures in the TCP/IP environment on your system." />
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<meta name="DC.Relation" scheme="URI" content="rzamvtcpipplan.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzamvtcpserverstart.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzamvtcppreventproc.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="tcpsecurenv" />
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<meta name="DC.Language" content="en-us" />
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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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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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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>Secure your TCP/IP environment</title>
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</head>
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<body id="tcpsecurenv"><a name="tcpsecurenv"><!-- --></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">Secure your TCP/IP environment</h1>
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<div><p>This topic provides general suggestions for steps that you can
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take to reduce the security exposures in the TCP/IP environment on your system. </p>
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<div class="p">These tips apply to your entire TCP/IP environment rather than to the specific
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applications that are discussed in the topics that follow:<ul><li>When you write an application for a TCP/IP port, make sure that the application
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is properly secure. You should assume that an outsider might try to access
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that application through that port. A knowledgeable outsider may attempt to
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TELNET to that application.</li>
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<li>Monitor the use of TCP/IP ports on your system. A user application that
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is associated with a TCP/IP port can provide “back-door” entry to your system
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without a user ID or a password. Someone with sufficient authority on your
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system can associate an application with a TCP or UDP port.</li>
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<li>As a security administrator, you should be aware of a technique called
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IP spoofing that is used by hackers. Every system in a TCP/IP network has
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an IP address. Someone who uses IP spoofing sets up a system (usually a PC)
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to pretend to be an existing IP address or a trusted IP address. Thus, the
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imposter can establish a connection with your system by pretending to be a
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system that you normally connect with. <p>If you run TCP/IP on your system
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and your system participates in a network that is not physically protected,
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such as all nonswitched lines and predefined links, you are vulnerable to
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IP spoofing. To protect your system from damage by a <span class="q">"spoofer,"</span> start
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with the suggestions in this chapter, for example, sign-on protection and
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object security. You should also ensure that your system has reasonable auxiliary
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storage limits set. This prevents a spoofer from flooding your system with
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mail or spooled files to the point that your system becomes inoperable. In
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addition, you should regularly monitor TCP/IP activity on your system. If
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you detect IP spoofing, you can try to discover the weak points in your TCP/IP
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setup and to make adjustments.</p>
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<p>For your intranet, your company's private
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network of systems that do not need to connect directly to the outside, use
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IP addresses that are reusable. Reusable addresses are intended for use within
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a private network. The Internet backbone does not route packets that have
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a reusable IP address. Therefore, reusable addresses provide an added layer
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of protection inside your firewall. <a href="../rzai2/rzai2kickoff.htm">TCP/IP
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Setup</a> provides more information about how IP addresses are assigned
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and about the ranges of IP addresses, as well as security information about
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TCP/IP.</p>
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</li>
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</ul>
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</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rzamvtcpserverstart.htm">Control which TCP/IP servers start automatically</a></strong><br />
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As security administrator, you need to control which TCP/IP applications start automatically when you start TCP/IP.</li>
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<li class="ulchildlink"><strong><a href="rzamvtcppreventproc.htm">Prevent TCP/IP processing</a></strong><br />
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TCP/IP server jobs run in the QSYSWRK subsystem. You use the Start TCP/IP (STRTCP) command to start TCP/IP on your system.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzamvtcpipplan.htm" title="TCP/IP (Transmission Control Protocol/Internet Protocol) is a common way that computers of all types communicate with each other.">Plan TCP/IP security</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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