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| author |   hongbotian <hongbo.tianhongbo@huawei.com> | 2015-11-30 01:35:09 -0500 |
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| committer | hongbotian <hongbo.tianhongbo@huawei.com> | 2015-11-30 01:36:35 -0500 |
| commit | cc40af334e619bb549038238507407866f774f8f (patch) | |
| tree | 43ddc1974f72997a57173151eafb23e6025a13c9 /rubbos/app/apache2/manual/misc/security_tips.html.en | |
| parent | 68e74fd78b2485e5914ce34a5b30f4485029e021 (diff) | |
upload apache
JIRA: BOTTLENECK-10
Change-Id: I67eae31de6dc824097dfa56ab454ba36fdd23a2c
Signed-off-by: hongbotian <hongbo.tianhongbo@huawei.com>
Diffstat (limited to 'rubbos/app/apache2/manual/misc/security_tips.html.en')
| -rw-r--r-- | rubbos/app/apache2/manual/misc/security_tips.html.en | 354 |
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diff --git a/rubbos/app/apache2/manual/misc/security_tips.html.en b/rubbos/app/apache2/manual/misc/security_tips.html.en new file mode 100644 index 00000000..560c8259 --- /dev/null +++ b/rubbos/app/apache2/manual/misc/security_tips.html.en @@ -0,0 +1,354 @@ +<?xml version="1.0" encoding="ISO-8859-1"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Security Tips - Apache HTTP Server</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /> +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body id="manual-page"><div id="page-header"> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.0</p> +<img alt="" src="../images/feather.gif" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> +<div id="path"> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.0</a> > <a href="./">Miscellaneous Documentation</a></div><div id="page-content"><div id="preamble"><h1>Security Tips</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/misc/security_tips.html" title="English"> en </a> | +<a href="../ko/misc/security_tips.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | +<a href="../tr/misc/security_tips.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> +</div> + + <p>Some hints and tips on security issues in setting up a web server. + Some of the suggestions will be general, others specific to Apache.</p> + </div> +<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#uptodate">Keep up to Date</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#serverroot">Permissions on ServerRoot Directories</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#ssi">Server Side Includes</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#cgi">CGI in General</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#nsaliasedcgi">Non Script Aliased CGI</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#saliasedcgi">Script Aliased CGI</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#dynamic">Other sources of dynamic content</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#systemsettings">Protecting System Settings</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#protectserverfiles">Protect Server Files by Default</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#watchyourlogs">Watching Your Logs</a></li> +</ul></div> +<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="uptodate" id="uptodate">Keep up to Date</a></h2> + + <p>The Apache HTTP Server has a good record for security and a + developer community highly concerned about security issues. But + it is inevitable that some problems -- small or large -- will be + discovered in software after it is released. For this reason, it + is crucial to keep aware of updates to the software. If you have + obtained your version of the HTTP Server directly from Apache, we + highly recommend you subscribe to the <a href="http://httpd.apache.org/lists.html#http-announce">Apache + HTTP Server Announcements List</a> where you can keep informed of + new releases and security updates. Similar services are available + from most third-party distributors of Apache software.</p> + + <p>Of course, most times that a web server is compromised, it is + not because of problems in the HTTP Server code. Rather, it comes + from problems in add-on code, CGI scripts, or the underlying + Operating System. You must therefore stay aware of problems and + updates with all the software on your system.</p> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="serverroot" id="serverroot">Permissions on ServerRoot Directories</a></h2> + + + + <p>In typical operation, Apache is started by the root user, and it + switches to the user defined by the <code class="directive"><a href="../mod/mpm_common.html#user">User</a></code> directive to serve hits. As is the + case with any command that root executes, you must take care that it is + protected from modification by non-root users. Not only must the files + themselves be writeable only by root, but so must the directories, and + parents of all directories. For example, if you choose to place + ServerRoot in <code>/usr/local/apache</code> then it is suggested that + you create that directory as root, with commands like these:</p> + + <div class="example"><p><code> + mkdir /usr/local/apache <br /> + cd /usr/local/apache <br /> + mkdir bin conf logs <br /> + chown 0 . bin conf logs <br /> + chgrp 0 . bin conf logs <br /> + chmod 755 . bin conf logs + </code></p></div> + + <p>It is assumed that <code>/</code>, <code>/usr</code>, and + <code>/usr/local</code> are only modifiable by root. When you install the + <code class="program"><a href="../programs/httpd.html">httpd</a></code> executable, you should ensure that it is + similarly protected:</p> + + <div class="example"><p><code> + cp httpd /usr/local/apache/bin <br /> + chown 0 /usr/local/apache/bin/httpd <br /> + chgrp 0 /usr/local/apache/bin/httpd <br /> + chmod 511 /usr/local/apache/bin/httpd + </code></p></div> + + <p>You can create an htdocs subdirectory which is modifiable by other + users -- since root never executes any files out of there, and shouldn't + be creating files in there.</p> + + <p>If you allow non-root users to modify any files that root either + executes or writes on then you open your system to root compromises. + For example, someone could replace the <code class="program"><a href="../programs/httpd.html">httpd</a></code> binary so + that the next time you start it, it will execute some arbitrary code. If + the logs directory is writeable (by a non-root user), someone could replace + a log file with a symlink to some other system file, and then root + might overwrite that file with arbitrary data. If the log files + themselves are writeable (by a non-root user), then someone may be + able to overwrite the log itself with bogus data.</p> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="ssi" id="ssi">Server Side Includes</a></h2> + + + + <p>Server Side Includes (SSI) present a server administrator with + several potential security risks.</p> + + <p>The first risk is the increased load on the server. All + SSI-enabled files have to be parsed by Apache, whether or not + there are any SSI directives included within the files. While this + load increase is minor, in a shared server environment it can become + significant.</p> + + <p>SSI files also pose the same risks that are associated with CGI + scripts in general. Using the <code>exec cmd</code> element, SSI-enabled + files can execute any CGI script or program under the permissions of the + user and group Apache runs as, as configured in + <code>httpd.conf</code>.</p> + + <p>There are ways to enhance the security of SSI files while still + taking advantage of the benefits they provide.</p> + + <p>To isolate the damage a wayward SSI file can cause, a server + administrator can enable <a href="../suexec.html">suexec</a> as + described in the <a href="#cgi">CGI in General</a> section.</p> + + <p>Enabling SSI for files with <code>.html</code> or <code>.htm</code> + extensions can be dangerous. This is especially true in a shared, or high + traffic, server environment. SSI-enabled files should have a separate + extension, such as the conventional <code>.shtml</code>. This helps keep + server load at a minimum and allows for easier management of risk.</p> + + <p>Another solution is to disable the ability to run scripts and + programs from SSI pages. To do this replace <code>Includes</code> + with <code>IncludesNOEXEC</code> in the <code class="directive"><a href="../mod/core.html#options">Options</a></code> directive. Note that users may + still use <code><--#include virtual="..." --></code> to execute CGI + scripts if these scripts are in directories designated by a <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code> directive.</p> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="cgi" id="cgi">CGI in General</a></h2> + + + + <p>First of all, you always have to remember that you must trust the + writers of the CGI scripts/programs or your ability to spot potential + security holes in CGI, whether they were deliberate or accidental. CGI + scripts can run essentially arbitrary commands on your system with the + permissions of the web server user and can therefore be extremely + dangerous if they are not carefully checked.</p> + + <p>All the CGI scripts will run as the same user, so they have potential + to conflict (accidentally or deliberately) with other scripts e.g. User + A hates User B, so he writes a script to trash User B's CGI database. One + program which can be used to allow scripts to run as different users is + <a href="../suexec.html">suEXEC</a> which is included with Apache as of + 1.2 and is called from special hooks in the Apache server code. Another + popular way of doing this is with + <a href="http://cgiwrap.unixtools.org/">CGIWrap</a>.</p> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="nsaliasedcgi" id="nsaliasedcgi">Non Script Aliased CGI</a></h2> + + + + <p>Allowing users to execute CGI scripts in any directory should only be + considered if:</p> + + <ul> + <li>You trust your users not to write scripts which will deliberately + or accidentally expose your system to an attack.</li> + <li>You consider security at your site to be so feeble in other areas, + as to make one more potential hole irrelevant.</li> + <li>You have no users, and nobody ever visits your server.</li> + </ul> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="saliasedcgi" id="saliasedcgi">Script Aliased CGI</a></h2> + + + + <p>Limiting CGI to special directories gives the admin control over what + goes into those directories. This is inevitably more secure than non + script aliased CGI, but only if users with write access to the + directories are trusted or the admin is willing to test each + new CGI script/program for potential security holes.</p> + + <p>Most sites choose this option over the non script aliased CGI + approach.</p> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="dynamic" id="dynamic">Other sources of dynamic content</a></h2> + + + + <p>Embedded scripting options which run as part of the server itself, + such as <code>mod_php</code>, <code>mod_perl</code>, <code>mod_tcl</code>, + and <code>mod_python</code>, run under the identity of the server itself + (see the <code class="directive"><a href="../mod/mpm_common.html#user">User</a></code> directive), and + therefore scripts executed by these engines potentially can access + anything the server user can. Some scripting engines may provide + restrictions, but it is better to be safe and assume not.</p> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="systemsettings" id="systemsettings">Protecting System Settings</a></h2> + + + + <p>To run a really tight ship, you'll want to stop users from setting + up <code>.htaccess</code> files which can override security features + you've configured. Here's one way to do it.</p> + + <p>In the server configuration file, put</p> + + <div class="example"><p><code> + <Directory /> <br /> + AllowOverride None <br /> + </Directory> + </code></p></div> + + <p>This prevents the use of <code>.htaccess</code> files in all + directories apart from those specifically enabled.</p> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="protectserverfiles" id="protectserverfiles">Protect Server Files by Default</a></h2> + + + + <p>One aspect of Apache which is occasionally misunderstood is the + feature of default access. That is, unless you take steps to change it, + if the server can find its way to a file through normal URL mapping + rules, it can serve it to clients.</p> + + <p>For instance, consider the following example:</p> + + <div class="example"><p><code> + # cd /; ln -s / public_html <br /> + Accessing <code>http://localhost/~root/</code> + </code></p></div> + + <p>This would allow clients to walk through the entire filesystem. To + work around this, add the following block to your server's + configuration:</p> + + <div class="example"><p><code> + <Directory /> <br /> + Order Deny,Allow <br /> + Deny from all <br /> + </Directory> + </code></p></div> + + <p>This will forbid default access to filesystem locations. Add + appropriate <code class="directive"><a href="../mod/core.html#directory">Directory</a></code> blocks to + allow access only in those areas you wish. For example,</p> + + <div class="example"><p><code> + <Directory /usr/users/*/public_html> <br /> + Order Deny,Allow <br /> + Allow from all <br /> + </Directory> <br /> + <Directory /usr/local/httpd> <br /> + Order Deny,Allow <br /> + Allow from all <br /> + </Directory> + </code></p></div> + + <p>Pay particular attention to the interactions of <code class="directive"><a href="../mod/core.html#location">Location</a></code> and <code class="directive"><a href="../mod/core.html#directory">Directory</a></code> directives; for instance, even + if <code><Directory /></code> denies access, a <code> + <Location /></code> directive might overturn it.</p> + + <p>Also be wary of playing games with the <code class="directive"><a href="../mod/mod_userdir.html#userdir">UserDir</a></code> directive; setting it to + something like <code>./</code> would have the same effect, for root, as + the first example above. If you are using Apache 1.3 or above, we strongly + recommend that you include the following line in your server + configuration files:</p> + + <div class="example"><p><code> + UserDir disabled root + </code></p></div> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="watchyourlogs" id="watchyourlogs">Watching Your Logs</a></h2> + + + + <p>To keep up-to-date with what is actually going on against your server + you have to check the <a href="../logs.html">Log Files</a>. Even though + the log files only reports what has already happened, they will give you + some understanding of what attacks is thrown against the server and + allow you to check if the necessary level of security is present.</p> + + <p>A couple of examples:</p> + + <div class="example"><p><code> + grep -c "/jsp/source.jsp?/jsp/ /jsp/source.jsp??" access_log <br /> + grep "client denied" error_log | tail -n 10 + </code></p></div> + + <p>The first example will list the number of attacks trying to exploit the + <a href="http://online.securityfocus.com/bid/4876/info/">Apache Tomcat + Source.JSP Malformed Request Information Disclosure Vulnerability</a>, + the second example will list the ten last denied clients, for example:</p> + + <div class="example"><p><code> + [Thu Jul 11 17:18:39 2002] [error] [client foo.bar.com] client denied + by server configuration: /usr/local/apache/htdocs/.htpasswd + </code></p></div> + + <p>As you can see, the log files only report what already has happened, so + if the client had been able to access the <code>.htpasswd</code> file you + would have seen something similar to:</p> + + <div class="example"><p><code> + foo.bar.com - - [12/Jul/2002:01:59:13 +0200] "GET /.htpasswd HTTP/1.1" + </code></p></div> + + <p>in your <a href="../logs.html#accesslog">Access Log</a>. This means + you probably commented out the following in your server configuration + file:</p> + + <div class="example"><p><code> + <Files ~ "^\.ht"> <br /> + Order allow,deny <br /> + Deny from all <br /> + </Files> + </code></p></div> + + </div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/misc/security_tips.html" title="English"> en </a> | +<a href="../ko/misc/security_tips.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | +<a href="../tr/misc/security_tips.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> +</div><div id="footer"> +<p class="apache">Copyright 2009 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div> +</body></html>
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