140 lines
9.2 KiB
HTML
140 lines
9.2 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 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="FTP security" />
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<meta name="abstract" content="FTP (File Transfer Protocol) provides the capability of transferring files between a client (a user on another system) and your server." />
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<meta name="description" content="FTP (File Transfer Protocol) provides the capability of transferring files between a client (a user on another system) and your server." />
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<meta name="DC.Relation" scheme="URI" content="rzaj45zrscenario1risks.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzaj45zoemail.htm" />
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<meta name="DC.Relation" scheme="URI" content="../rzalx/rzalxsecterms.htm" />
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<meta name="DC.Relation" scheme="URI" content="../rzaja/rzajagetstart.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzaj40a0internetsecurity.htm" />
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<meta name="DC.Relation" scheme="URI" content="../rzaub/rzaubkickoff.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1999, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rzaj45zpftpsolutions" />
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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>FTP security</title>
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</head>
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<body id="rzaj45zpftpsolutions"><a name="rzaj45zpftpsolutions"><!-- --></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">FTP security</h1>
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<div><p>FTP (File Transfer Protocol) provides the capability of transferring
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files between a client (a user on another system) and your server.</p>
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<p>You can also use the remote command capability to submit commands to the
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server. Consequently, FTP is very useful for working with remote systems,
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or to move files between systems. However, the use of FTP across the Internet,
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or other untrusted networks, exposes you to certain security risks. You must
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understand these risks to ensure that your security policy describes how you
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will minimize these risks.</p>
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<ul><li>Your object authority scheme might not provide enough protection when
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you allow FTP on your system. <p>For example, the public authority for your
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objects may be *USE, but today you are preventing most users from accessing
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those objects by using "menu security". (Menu security prevents users from
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doing anything that is not one of their menu options.) Since FTP users are
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not restricted to menus, they can read all objects on your system.</p>
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<div class="p"><img src="./delta.gif" alt="Start of change" />Here
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are some options for controlling this security risk: <ul><li>Put into effect full iSeries™ object security on the system (in other words,
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change the system's security model from "menu security" to "object security."
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This is your best, most secure option.</li>
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<li>Write exit programs for FTP to restrict access to files which may be transferred
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through FTP. These exit programs should provide security that is at least
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the equivalent as the security that the menu program provide. Many customers
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would probably want to make the FTP access controls even more restrictive.
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This option only covers FTP, not other interfaces such as ODBC, DDM, or DRDA<sup>®</sup>. <div class="note"><span class="notetitle">Note:</span> *USE
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authority to a file allows the user to download the file. *CHANGE authority
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to a file allows the user to upload the file.</div>
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</li>
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</ul>
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<img src="./deltaend.gif" alt="End of change" /></div>
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</li>
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<li>A hacker can mount a "denial of service" attack with your FTP server to
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disable user profiles on the system. This is done by repeatedly attempting
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to log on with an incorrect password for a user profile until the user profile
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is disabled. This type of attack disables the profile if it reaches the maximum
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sign on count of three. <p>What you can do to avoid this risk involves analyzing
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the trade-offs that you are willing to make to increase security to minimize
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the attack versus providing users with ease of access. The FTP server normally
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enforces the QMAXSIGN system value to prevent a hacker from having unlimited
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attempts to guess a password and therefore mount password attacks. Here are
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some options that you should consider using:</p>
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<ul><li>Use an FTP server logon exit program to reject logon requests by any system
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user profiles and those user profiles that you designate not be allowed FTP
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access. (When using such an exit program, logon attempts rejected by the
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server logon exit point for the user profiles that you block do <strong>not</strong> get
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counted against the profile's QMAXSIGN count.)</li>
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<li>Use an FTP server logon exit program to limit the client machines from
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which a given user profile is allowed to access the FTP server. For example,
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if a person from Accounting is allowed FTP access, only allow that user profile
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FTP server access from computers which have IP addresses in the Accounting
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department.</li>
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<li>Use an FTP server logon exit program to log the user name and IP address
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of all FTP logon attempts. Review these logs regularly, and whenever a profile
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is disabled by maximum password attempts, use the IP address information to
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identify the perpetrator and take appropriate measures.</li>
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<li><img src="./delta.gif" alt="Start of change" />Use the intrusion detection system to detect "denial of service"
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attacks on the system.<img src="./deltaend.gif" alt="End of change" /></li>
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</ul>
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</li>
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</ul>
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<p>Additionally, you can use FTP server exit points to provide an anonymous
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FTP function for guest users. Setting up a secure, anonymous FTP server requires
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exit programs for both the FTP server logon <strong>and</strong> FTP server request
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validation exit points.</p>
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<p><img src="./delta.gif" alt="Start of change" />You can use the Secure Sockets Layer (SSL) to provide secure
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communications sessions for your FTP server. Using SSL ensures that all FTP
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transmissions are encrypted to maintain confidentiality for all data that
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passes between the FTP server and the client, including user names and passwords.
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The FTP server supports the use of digital certificates for client authentication
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also.<img src="./deltaend.gif" alt="End of change" /></p>
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<div class="p">To learn more about using FTP, its risks, and
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the security measures available to you, review these resources: <ul><li><a href="../rzaiq/rzaiqrzaiqimplement.htm">Secure
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FTP</a>.</li>
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<li><a href=" ../rzaiq/rzaiqsslparent.htm">Use
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SSL to secure the FTP server</a>.</li>
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</ul>
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</div>
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<p><img src="./delta.gif" alt="Start of change" />In addition to these FTP options, you may want
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to consider using Anonymous FTP to provide a convenient way for users to access
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non-confidential material easily. Anonymous FTP enables unprotected access
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(no password required) to selected information about a remote system. The
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remote site determines what information is made available for general access.
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Such information is considered to be publicly accessible and can be read by
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anyone. Before configure Anonymous FTP, you should weigh the security risks
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and consider securing your FTP server with exit programs.<img src="./deltaend.gif" alt="End of change" /></p>
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<ul><li><a href="../rzaiq/rzaiqftpanon.htm">Configure
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Anonymous FTP</a>.</li>
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<li><a href="../rzaiq/rzaiqftpscon.htm">Manage
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access using FTP exit programs</a>.</li>
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</ul>
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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="rzaj45zrscenario1risks.htm" title="Use this information to learn about common Internet security risks for a number of popular Internet applications and services and measures that you can take to manage these risks.">Application security options</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="rzaj45zoemail.htm" title="Using e-mail across the Internet or other untrusted network imposes security risks against which using a firewall may not protect.">E-mail security</a></div>
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<div><a href="../rzaja/rzajagetstart.htm">Virtual private network (VPN)</a></div>
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<div><a href="rzaj40a0internetsecurity.htm" title="Your security policy defines what you want to protect and what you expect of your system users.">The layered defense approach to security</a></div>
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<div><a href="../rzaub/rzaubkickoff.htm">Intrusion detection</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="../rzalx/rzalxsecterms.htm">Security terminology</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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