99 lines
6.3 KiB
HTML
99 lines
6.3 KiB
HTML
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<meta name="DC.Title" content="Security considerations for using point-to-point protocol" />
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<meta name="abstract" content="Point-to-point protocol (PPP) is available as part of TCP/IP." />
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<title>Security considerations for using point-to-point protocol</title>
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<body id="tcpsecppp"><a name="tcpsecppp"><!-- --></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">Security considerations for using point-to-point protocol</h1>
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<div><p>Point-to-point protocol (PPP) is available as part of TCP/IP.</p>
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<p> PPP is an industry standard for point-to-point connections that provides
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additional function over what is available with SLIP. With PPP, your iSeries™ server
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can have high-speed connections directly to an Internet Service Provider or
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to other systems in an intranet or extranet. Remote LANs can realistically
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make dial-in connections to your iSeries server. </p>
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<div class="p">Remember that PPP, like SLIP, provides a network connection to your iSeries server.
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A PPP connection essentially brings the requester to your system’s door. The
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requester still needs a user ID and password to enter your system and connect
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to a TCP/IP server like TELNET or FTP. Following are security considerations
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with this new connection capability:<div class="note"><span class="notetitle">Note:</span> You configure PPP by using iSeries Navigator
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on an IBM<sup>®</sup> iSeries Access
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for Windows<sup>®</sup> workstation.</div>
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<ul><li>PPP provides the ability to have dedicated connections (where the same
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user always has the same IP address). With a dedicated address, you have the
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potential for IP spoofing (an imposter system that pretends to be a trusted
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system with a known IP address). However, the enhanced authentication capabilities
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that PPP provides help protect against IP spoofing.</li>
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<li>With PPP, as with SLIP, you create connection profiles that have a user
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name and an associated password. However, unlike SLIP, the user does not need
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to have a valid user profile and password. The user name and password are
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not associated with a user profile. Instead, validation lists are used for
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PPP authentication. Additionally, PPP does not require a connection script.
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The authentication (exchange of user name and password) is part of the PPP
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architecture and happens at a lower level than with SLIP.</li>
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<li>With PPP, you have the option to use CHAP (challenge handshake authentication
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protocol). You will no longer need to worry about an eavesdropper sniffing
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passwords because CHAP encrypts user names and passwords. <p>Your PPP connection
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uses CHAP only if both sides have CHAP support. During the exchange signals
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to set up communications between two modems, the two systems negotiate. For
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example, if SYSTEMA supports CHAP and SYSTEMB does not, SYSTEMA can either
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deny the session or agree to use an unencrypted user name and password. Agreeing
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to use an unencrypted user name and password is referred to as negotiating
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down. </p>
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<p>The decision to negotiate down is a configuration option. On
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your intranet, for example, where you know that all your systems have CHAP
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capability, you should configure your connection profile so that it will not
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negotiate down. On a public connection where your system is dialing out, you
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might be willing to negotiate down. The connection profile for PPP provides
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the ability to specify valid IP addresses. You can, for example, indicate
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that you expect a specific address or range of addresses for a specific user. </p>
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<p>This
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capability, together with the ability for encrypted passwords, provides further
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protection against spoofing. As additional protection against spoofing or
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piggy-backing on an active session, you can configure PPP to rechallenge at
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designated intervals. For example, while a PPP session is active, your iSeries server
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might challenge the other system for a user and password. It does this every
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15 minutes to ensure that `it is the same connection profile. </p>
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<p>The end-user
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will not be aware of this rechallenge activity. The systems exchange names
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and passwords below the level that the end-user sees. With PPP, it is realistic
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to expect that remote LANs might establish a dial-in connection to your iSeries server
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and to your extended network. In this environment, having IP forwarding turned
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on is probably a requirement. IP forwarding has the potential to allow an
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intruder to roam through your network. However, PPP has stronger protections
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(such as encryption of passwords and IP address validation). This makes it
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less likely that an intruder can establish a network connection in the first
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place.</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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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzamvtcpsetupsecurity.htm" title="The following information guides you through the process of setting up TCP/IP security.">Set up TCP/IP security</a></div>
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</div>
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</div>
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</body>
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