htdocs/manual/misc/howto.html - httpd - Git at Google

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     <h1 align="CENTER">Apache HOWTO documentation</h1>
     How to:

     <ul>
       <li><a href="#redirect">redirect an entire server or
       directory to a single URL</a></li>

       <li><a href="#logreset">reset your log files</a></li>

       <li><a href="#stoprob">stop/restrict robots</a></li>

       <li><a href="#proxyssl">proxy SSL requests <em>through</em>
       your non-SSL server</a></li>
     </ul>
     <hr />

     <h2><a id="redirect" name="redirect">How to redirect an entire
     server or directory to a single URL</a></h2>

     <p>There are two chief ways to redirect all requests for an
     entire server to a single location: one which requires the use
     of <code>mod_rewrite</code>, and another which uses a CGI
     script.</p>

     <p>First: if all you need to do is migrate a server from one
     name to another, simply use the <code>Redirect</code>
     directive, as supplied by <code>mod_alias</code>:</p>

     <blockquote>
 <pre>
   Redirect / http://www.apache.org/
 </pre>
     </blockquote>

     <p>Since <code>Redirect</code> will forward along the complete
     path, however, it may not be appropriate - for example, when
     the directory structure has changed after the move, and you
     simply want to direct people to the home page.</p>

     <p>The best option is to use the standard Apache module
     <code>mod_rewrite</code>. If that module is compiled in, the
     following lines</p>

     <blockquote>
 <pre>
 RewriteEngine On
 RewriteRule /.* http://www.apache.org/ [R]
 </pre>
     </blockquote>
     will send an HTTP 302 Redirect back to the client, and no
     matter what they gave in the original URL, they'll be sent to
     "http://www.apache.org/".

     <p>The second option is to set up a <code>ScriptAlias</code>
     pointing to a <strong>CGI script</strong> which outputs a 301
     or 302 status and the location of the other server.</p>

     <p>By using a <strong>CGI script</strong> you can intercept
     various requests and treat them specially, <em>e.g.</em>, you
     might want to intercept <strong>POST</strong> requests, so that
     the client isn't redirected to a script on the other server
     which expects POST information (a redirect will lose the POST
     information.) You might also want to use a CGI script if you
     don't want to compile mod_rewrite into your server.</p>

     <p>Here's how to redirect all requests to a script... In the
     server configuration file,</p>

     <blockquote>
 <pre>
 ScriptAlias / /usr/local/httpd/cgi-bin/redirect_script/
 </pre>
     </blockquote>
     and here's a simple perl script to redirect requests:

     <blockquote>
 <pre>
 #!/usr/local/bin/perl

 print "Status: 302 Moved Temporarily\r\n" .
       "Location: http://www.some.where.else.com/\r\n" .
       "\r\n";

 </pre>
     </blockquote>
     <hr />

     <h2><a id="logreset" name="logreset">How to reset your log
     files</a></h2>

     <p>Sooner or later, you'll want to reset your log files
     (access_log and error_log) because they are too big, or full of
     old information you don't need.</p>

     <p><code>access.log</code> typically grows by 1Mb for each
     10,000 requests.</p>

     <p>Most people's first attempt at replacing the logfile is to
     just move the logfile or remove the logfile. This doesn't
     work.</p>

     <p>Apache will continue writing to the logfile at the same
     offset as before the logfile moved. This results in a new
     logfile being created which is just as big as the old one, but
     it now contains thousands (or millions) of null characters.</p>

     <p>The correct procedure is to move the logfile, then signal
     Apache to tell it to reopen the logfiles.</p>

     <p>Apache is signaled using the <strong>SIGHUP</strong> (-1)
     signal. <em>e.g.</em></p>

     <blockquote>
       <code>mv access_log access_log.old<br />
        kill -1 `cat httpd.pid`</code>
     </blockquote>

     <p>Note: <code>httpd.pid</code> is a file containing the
     <strong>p</strong>rocess <strong>id</strong> of the Apache
     httpd daemon, Apache saves this in the same directory as the
     log files.</p>

     <p>Many people use this method to replace (and backup) their
     logfiles on a nightly or weekly basis.</p>
     <hr />

     <h2><a id="stoprob" name="stoprob">How to stop or restrict
     robots</a></h2>

     <p>Ever wondered why so many clients are interested in a file
     called <code>robots.txt</code> which you don't have, and never
     did have?</p>

     <p>These clients are called <strong>robots</strong> (also known
     as crawlers, spiders and other cute names) - special automated
     clients which wander around the web looking for interesting
     resources.</p>

     <p>Most robots are used to generate some kind of <em>web
     index</em> which is then used by a <em>search engine</em> to
     help locate information.</p>

     <p><code>robots.txt</code> provides a means to request that
     robots limit their activities at the site, or more often than
     not, to leave the site alone.</p>

     <p>When the first robots were developed, they had a bad
     reputation for sending hundreds/thousands of requests to each
     site, often resulting in the site being overloaded. Things have
     improved dramatically since then, thanks to <a
     href="http://www.robotstxt.org/wc/guidelines.html">
     Guidelines for Robot Writers</a>, but even so, some robots may
     exhibit unfriendly behavior which the webmaster isn't willing
     to tolerate, and will want to stop.</p>

     <p>Another reason some webmasters want to block access to
     robots, is to stop them indexing dynamic information. Many
     search engines will use the data collected from your pages for
     months to come - not much use if you're serving stock quotes,
     news, weather reports or anything else that will be stale by
     the time people find it in a search engine.</p>

     <p>If you decide to exclude robots completely, or just limit
     the areas in which they can roam, create a
     <code>robots.txt</code> file; refer to the <a
     href="http://www.robotstxt.org/wc/robots.html">
     robot information pages</a> provided by Martijn Koster for the
     syntax.</p>
     <hr />

     <h2><a id="proxyssl" name="proxyssl">How to proxy SSL requests
     <em>through</em> your non-SSL Apache server</a><br />
      <small>(<em>submitted by David Sedlock</em>)</small></h2>

     <p>SSL uses port 443 for requests for secure pages. If your
     browser just sits there for a long time when you attempt to
     access a secure page over your Apache proxy, then the proxy may
     not be configured to handle SSL. You need to instruct Apache to
     listen on port 443 in addition to any of the ports on which it
     is already listening:</p>
 <pre>
     Listen 80
     Listen 443
 </pre>

     <p>Then set the security proxy in your browser to 443. That
     might be it!</p>

     <p>If your proxy is sending requests to another proxy, then you
     may have to set the directive ProxyRemote differently. Here are
     my settings:</p>
 <pre>
     ProxyRemote http://nicklas:80/ http://proxy.mayn.franken.de:8080
     ProxyRemote http://nicklas:443/ http://proxy.mayn.franken.de:443
 </pre>

     <p>Requests on port 80 of my proxy <samp>nicklas</samp> are
     forwarded to <samp>proxy.mayn.franken.de:8080</samp>, while
     requests on port 443 are forwarded to
     <samp>proxy.mayn.franken.de:443</samp>. If the remote proxy is
     not set up to handle port 443, then the last directive can be
     left out. SSL requests will only go over the first proxy.</p>

     <p>Note that your Apache does NOT have to be set up to serve
     secure pages with SSL. Proxying SSL is a different thing from
     using it.</p>
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	<head>
	<META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW">
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	<meta name="description"
	content="Some 'how to' tips for the Apache httpd server" />
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	</head>
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	<h1 align="CENTER">Apache HOWTO documentation</h1>
	How to:

	<ul>
	<li><a href="#redirect">redirect an entire server or
	directory to a single URL</a></li>

	<li><a href="#logreset">reset your log files</a></li>

	<li><a href="#stoprob">stop/restrict robots</a></li>

	<li><a href="#proxyssl">proxy SSL requests <em>through</em>
	your non-SSL server</a></li>
	</ul>
	<hr />

	<h2><a id="redirect" name="redirect">How to redirect an entire
	server or directory to a single URL</a></h2>

	<p>There are two chief ways to redirect all requests for an
	entire server to a single location: one which requires the use
	of <code>mod_rewrite</code>, and another which uses a CGI
	script.</p>

	<p>First: if all you need to do is migrate a server from one
	name to another, simply use the <code>Redirect</code>
	directive, as supplied by <code>mod_alias</code>:</p>

	<blockquote>
	<pre>
	Redirect / http://www.apache.org/
	</pre>
	</blockquote>

	<p>Since <code>Redirect</code> will forward along the complete
	path, however, it may not be appropriate - for example, when
	the directory structure has changed after the move, and you
	simply want to direct people to the home page.</p>

	<p>The best option is to use the standard Apache module
	<code>mod_rewrite</code>. If that module is compiled in, the
	following lines</p>

	<blockquote>
	<pre>
	RewriteEngine On
	RewriteRule /.* http://www.apache.org/ [R]
	</pre>
	</blockquote>
	will send an HTTP 302 Redirect back to the client, and no
	matter what they gave in the original URL, they'll be sent to
	"http://www.apache.org/".

	<p>The second option is to set up a <code>ScriptAlias</code>
	pointing to a <strong>CGI script</strong> which outputs a 301
	or 302 status and the location of the other server.</p>

	<p>By using a <strong>CGI script</strong> you can intercept
	various requests and treat them specially, <em>e.g.</em>, you
	might want to intercept <strong>POST</strong> requests, so that
	the client isn't redirected to a script on the other server
	which expects POST information (a redirect will lose the POST
	information.) You might also want to use a CGI script if you
	don't want to compile mod_rewrite into your server.</p>

	<p>Here's how to redirect all requests to a script... In the
	server configuration file,</p>

	<blockquote>
	<pre>
	ScriptAlias / /usr/local/httpd/cgi-bin/redirect_script/
	</pre>
	</blockquote>
	and here's a simple perl script to redirect requests:

	<blockquote>
	<pre>
	#!/usr/local/bin/perl

	print "Status: 302 Moved Temporarily\r\n" .
	"Location: http://www.some.where.else.com/\r\n" .
	"\r\n";

	</pre>
	</blockquote>
	<hr />

	<h2><a id="logreset" name="logreset">How to reset your log
	files</a></h2>

	<p>Sooner or later, you'll want to reset your log files
	(access_log and error_log) because they are too big, or full of
	old information you don't need.</p>

	<p><code>access.log</code> typically grows by 1Mb for each
	10,000 requests.</p>

	<p>Most people's first attempt at replacing the logfile is to
	just move the logfile or remove the logfile. This doesn't
	work.</p>

	<p>Apache will continue writing to the logfile at the same
	offset as before the logfile moved. This results in a new
	logfile being created which is just as big as the old one, but
	it now contains thousands (or millions) of null characters.</p>

	<p>The correct procedure is to move the logfile, then signal
	Apache to tell it to reopen the logfiles.</p>

	<p>Apache is signaled using the <strong>SIGHUP</strong> (-1)
	signal. <em>e.g.</em></p>

	<blockquote>
	<code>mv access_log access_log.old<br />
	kill -1 `cat httpd.pid`</code>
	</blockquote>

	<p>Note: <code>httpd.pid</code> is a file containing the
	<strong>p</strong>rocess <strong>id</strong> of the Apache
	httpd daemon, Apache saves this in the same directory as the
	log files.</p>

	<p>Many people use this method to replace (and backup) their
	logfiles on a nightly or weekly basis.</p>
	<hr />

	<h2><a id="stoprob" name="stoprob">How to stop or restrict
	robots</a></h2>

	<p>Ever wondered why so many clients are interested in a file
	called <code>robots.txt</code> which you don't have, and never
	did have?</p>

	<p>These clients are called <strong>robots</strong> (also known
	as crawlers, spiders and other cute names) - special automated
	clients which wander around the web looking for interesting
	resources.</p>

	<p>Most robots are used to generate some kind of <em>web
	index</em> which is then used by a <em>search engine</em> to
	help locate information.</p>

	<p><code>robots.txt</code> provides a means to request that
	robots limit their activities at the site, or more often than
	not, to leave the site alone.</p>

	<p>When the first robots were developed, they had a bad
	reputation for sending hundreds/thousands of requests to each
	site, often resulting in the site being overloaded. Things have
	improved dramatically since then, thanks to <a
	href="http://www.robotstxt.org/wc/guidelines.html">
	Guidelines for Robot Writers</a>, but even so, some robots may
	exhibit unfriendly behavior which the webmaster isn't willing
	to tolerate, and will want to stop.</p>

	<p>Another reason some webmasters want to block access to
	robots, is to stop them indexing dynamic information. Many
	search engines will use the data collected from your pages for
	months to come - not much use if you're serving stock quotes,
	news, weather reports or anything else that will be stale by
	the time people find it in a search engine.</p>

	<p>If you decide to exclude robots completely, or just limit
	the areas in which they can roam, create a
	<code>robots.txt</code> file; refer to the <a
	href="http://www.robotstxt.org/wc/robots.html">
	robot information pages</a> provided by Martijn Koster for the
	syntax.</p>
	<hr />

	<h2><a id="proxyssl" name="proxyssl">How to proxy SSL requests
	<em>through</em> your non-SSL Apache server</a><br />
	<small>(<em>submitted by David Sedlock</em>)</small></h2>

	<p>SSL uses port 443 for requests for secure pages. If your
	browser just sits there for a long time when you attempt to
	access a secure page over your Apache proxy, then the proxy may
	not be configured to handle SSL. You need to instruct Apache to
	listen on port 443 in addition to any of the ports on which it
	is already listening:</p>
	<pre>
	Listen 80
	Listen 443
	</pre>

	<p>Then set the security proxy in your browser to 443. That
	might be it!</p>

	<p>If your proxy is sending requests to another proxy, then you
	may have to set the directive ProxyRemote differently. Here are
	my settings:</p>
	<pre>
	ProxyRemote http://nicklas:80/ http://proxy.mayn.franken.de:8080
	ProxyRemote http://nicklas:443/ http://proxy.mayn.franken.de:443
	</pre>

	<p>Requests on port 80 of my proxy <samp>nicklas</samp> are
	forwarded to <samp>proxy.mayn.franken.de:8080</samp>, while
	requests on port 443 are forwarded to
	<samp>proxy.mayn.franken.de:443</samp>. If the remote proxy is
	not set up to handle port 443, then the last directive can be
	left out. SSL requests will only go over the first proxy.</p>

	<p>Note that your Apache does NOT have to be set up to serve
	secure pages with SSL. Proxying SSL is a different thing from
	using it.</p>
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	</body>
	</html>