ch51.htm

linux-unix130.linux.and.unix.ebooks130 linux and unix ebookslinuxLearning Linux - Collection of 12 E

</Directory>

</FONT></PRE>

	<P>and anything between the beginning and ending delimiters (<TT>&lt;Directory&gt;</TT>

	and <TT>&lt;/Directory&gt;,</TT> respectively) are directives. It's not quite that

	easy, because there are several variations that can exist in the file. The best way

	to customize the <TT>access.conf-dist</TT> file is to follow these steps for a typical

	Web server installation:



	<DL>

	<DD><B>1.</B> Locate the Options directive and remove the Indexes option. This prevents

	users from browsing the <TT>httpd</TT> directory. Valid Options entries are discussed

	shortly.<BR>

	<BR>

	<B>2.</B> Locate the first Directory directive and check the path to the <TT>cgi-bin</TT>

	directory. The default path is <TT>/usr/local/etc/httpd/cgi-bin</TT>.<BR>

	<BR>

	<B>3.</B> Find the <TT>AllowOverride</TT> variable and set it to <TT>None</TT> (this

	prevents others from changing the settings). The default is <TT>All</TT>. Valid values

	for the <TT>AllowOverride</TT> variable are discussed shortly.<BR>

	<BR>

	<B>4. </B>Find the Limit directive and set it to whichever value you want.

	</DL>



	<P>The Limit directive controls access to your server. The following are valid values

	for the Limit directive: 

	<TABLE BORDER="0">

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>allow</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Allows specific host names following the <TT>allow</TT> keyword to access the service.

					</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>deny</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Denies specific host names following the <TT>deny</TT> keyword from accessing the

			service. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>order</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Specifies the order in which <TT>allow</TT> and <TT>deny</TT> directives are evaluated

			(usually set to <TT>deny,allow</TT> but can also be <TT>allow,deny</TT>). </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>require<BR>

			</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Requires authentication through a user file specified in the <TT>AuthUserFile</TT>

			entry.<BR>

					</TD>

	</TR>

	</TABLE>

The Options directive can have several entries, all of which have a different purpose.

	The default entry for Options is<FONT COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF">Options Indexes FollowSymLinks

</FONT></PRE>

	<P>You removed the Indexes entry from the Options directive in the first step of

	the preceding customization procedure. These entries all apply to the directory the

	<TT>Options</TT> field appears in. The valid entries for the Options directive are

	

	<TABLE BORDER="0">

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>All</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">All features enabled. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>ExecCGI</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>cgi</TT> scripts can be executed from this directory. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>FollowSymLinks</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Allows <TT>httpd</TT> to follow symbolic links. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>Includes</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>Include</TT> files for the server are enabled. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>IncludesNoExec</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>Include</TT> files for the server are enabled but the <TT>exec</TT> option is

			disabled. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>Indexes</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Enables users to retrieve server-generated indexes (doesn't affect precompiled indexes).

					</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>None</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">No features enabled. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>SymLinksIfOwnerMatch<BR>

			</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Follows symbolic links only if the user ID of the symbolic link matches the user

			ID of the file.<BR>

					</TD>

	</TR>

	</TABLE>

The <TT>AllowOverride</TT> variable is set to <TT>All</TT> by default, and this should

	be changed. There are several valid values for <TT>AllowOverride</TT>, but the recommended

	setting for most Linux systems is <TT>None</TT>. These are the valid values for <TT>AllowOverride</TT>:

	

	<TABLE BORDER="0">

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>All</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Access controlled by a configuration file in each directory. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>AuthConfig</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Enables some authentication routines. Valid values: <TT>AuthName</TT> (sets authorization

			name of directory); <TT>AuthType</TT> (sets authorization type of the directory,

			although there is only one legal value: <TT>Basic</TT>); <TT>AuthUserFile</TT> (specifies

			a file containing user names and passwords); and <TT>AuthGroupFile</TT> (specifies

			a file containing group names). </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>FileInfo</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Enables <TT>AddType</TT> and <TT>AddEncoding</TT> directives. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>Limit</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Enables <TT>Limit</TT> directive. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>None</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">No access files allowed. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT" VALIGN="TOP"><TT>Options<BR>

			</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Enables <TT>Options</TT> directive.<BR>

					</TD>

	</TR>

	</TABLE>

After all that, the configuration files should be properly set. While the syntax

	is a little confusing, reading the default values shows you the proper format to

	use when changing entries. Next, you can start the Web server software.

	<CENTER>

	<H4><A NAME="Heading8<FONT COLOR="#000077">Starting the Web Software</FONT></H4>

</CENTER>

	<P>With the configuration complete, it's time to try out the Web server software.

	In the configuration files, you made a decision as to whether the Web software will

	run as a daemon (standalone) or will start from <TT>inetd</TT>. The startup procedure

	is a little different for each method (as you would expect), but both startup procedures

	can use one of the following three options on the command line: 

	<TABLE BORDER="0">

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="30" ALIGN="LEFT" VALIGN="TOP"><TT>-d</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">The absolute path to the root directory of the server files (used only if the default

			location is not valid). </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="30" ALIGN="LEFT" VALIGN="TOP"><TT>-f</TT> </TD>

		<TD ALIGN="LEFT" VALIGN="TOP">The configuration file to read if not the default value of <TT>httpd.conf</TT>. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="30" ALIGN="LEFT" VALIGN="TOP"><TT>-v<BR>

			</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Displays the version number.<BR>

					</TD>

	</TR>

	</TABLE>

If you are using <TT>inetd</TT> to start your Web server software, you need to make

	a change to the <TT>/etc/ services</TT> file to permit the Web software. Add a line

	similar to this to the <TT>/etc/services</TT> file:<FONT COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF">http    port/tcp

</FONT></PRE>

	<P>Here, port is the port number used by your Web server software (usually 80).</P>

	<P>Next, modify the <TT>/etc/inetd.conf</TT> file to include the startup commands

	for the Web server where the last entry is the path to the <TT>httpd</TT> binary:<FONT

	COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF">httpd stream tcp nowait nobody /usr/web/httpd

</FONT></PRE>

	<P>Once this is done, restart <TT>inetd</TT> by killing and restarting the <TT>inetd</TT>

	process or by rebooting your system. The service should be available through whatever

	port you specified in <TT>/etc/services</TT>.</P>

	<P>If you are running the Web server software as a daemon, you can start it at any

	time from the command line with the following command:<FONT COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF">httpd &amp;

</FONT></PRE>

	<P>Even better, add the startup commands to the proper <TT>rc</TT> startup files.

	The entry usually looks like this:<FONT COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF"># start httpd

if [ -x /usr/web/httpd ]

then

 /usr/web/httpd

fi

</FONT></PRE>

	<P>substituting the proper paths for the <TT>httpd</TT> binary, of course. Rebooting

	your machine should start the Web server software on the default port number.</P>

	<P>To test the Web server software, use any Web browser and type the URL field<FONT

	COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF">http://machinename

</FONT></PRE>

	<P>where machinename is the name of your Web server. If you see the contents of the

	root Web directory or the <TT>index.html</TT> file, all is well. Otherwise, check

	the log files and configuration files for clues as to the problem.</P>

	<P>If you haven't installed a Web browser yet, you can still check to see if the

	Web server is running by using <TT>telnet</TT>. Issue a command like this, substituting

	the name of your server (and your Web port number if different than 80):<FONT COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF">telnet www.wizard.tpci.com 80

</FONT></PRE>

	<P>You should get a message similar to this if the Web server is responding properly:<FONT

	COLOR="#0066FF"></FONT>

	<PRE><FONT COLOR="#0066FF">Connected to wizard.tpci.com

Escape character is `^]'.

HEAD/HTTP/1.0

HTTP/1.0 200 OK

</FONT></PRE>

	<P>You'll also see some more lines showing details about the date and content. You

	may not be able to access anything, but this shows that the Web software is responding

	properly.

	<CENTER>

	<H3><A NAME="Heading9<FONT COLOR="#000077">Setting Up Your Web Site</FONT></H3>

</CENTER>

	<P>Having a server with nothing for content is useless, so you need to set up the

	information you will share through your Web system. This begins with Uniform Resource

	Locators (URLs), which are addresses to file locations. Anyone using your service

	only has to know the URL. You don't need to have anything fancy. If you don't have

	a special home page, anyone connecting to your system will get the contents of the

	Web root directory's <TT>index.html</TT> file, or failing that, a directory listing

	of the Web root directory. That's pretty boring, though, and most users want fancy

	home pages. To write a home page, you need to use HTML (HyperText Markup Language).</P>

	<P>A home page is like a main menu. Many users may not ever see it because they can

	enter into any of the subdirectories on your system, or obtain files from another

	Web system through a hyperlink, without ever seeing your home page. However, many

	users want to start at the top, and that's where your home page comes in. A home

	page file is usually called <TT>index.html</TT>. It is usually at the top of your

	Web source directories.</P>

	<P>Writing an HTML document is not too difficult. The language uses a set of tags

	to indicate how the text is to be treated (such as headlines, body text, figures,

	and so on). The tricky part of HTML is getting the tags in the right place, without

	extra material on a line. HTML is rather strict about its syntax, so errors must

	be avoided to prevent problems.</P>

	<P>In the early days of the Web, all documents were written with simple text editors.

	As the Web expanded, dedicated Web editors that understand HTML and the use of tags

	began to appear. Their popularity has driven developers to produce dozens of editors,

	filters, and utilities--all aimed at making a Web documenter's life easier (as well

	as to ensure that the HTML language is properly used). There are HTML editors for

	many operating systems.

	<CENTER>

	<H4><A NAME="Heading10<FONT COLOR="#000077">HTML Authoring Tools</FONT></H4>

</CENTER>

	<P>You can write HTML documents in many ways: You can use an ASCII editor, a word

	processor, or a dedicated HTML tool. The choice of which method you use depends on

	personal preference and your confidence in HTML coding, as well as which tools you

	can easily obtain. Because many HTML-specific tools have checking routines or filters

	to verify that your documents are correctly laid out and formatted, they can be appealing.

	They also tend to be more friendly than non-HTML editors. On the other hand, if you

	are a veteran programmer or writer, you may want to stick with your favorite editor