293 lines
5.1 KiB
HTML
293 lines
5.1 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>The /etc/hosts file</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.60"><LINK
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REL="HOME"
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TITLE="Securing and Optimizing Linux"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Files -Networking Functionality"
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HREF="file-netfunc.html"><LINK
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REL="PREVIOUS"
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TITLE="The /etc/sysctl.conf file"
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HREF="chap9sec94.html"><LINK
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REL="NEXT"
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TITLE="Config TCP/IP Networking manually -command line"
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HREF="chap9sec96.html"></HEAD
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CLASS="section"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Securing and Optimizing Linux: RedHat Edition -A Hands on Guide</TH
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><TD
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WIDTH="10%"
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ALIGN="left"
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HREF="chap9sec94.html"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 9. Files -Networking Functionality</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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>Next</A
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="section"
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><H1
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CLASS="section"
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><A
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NAME="AEN6160"
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>9.7. The <TT
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CLASS="filename"
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>/etc/hosts</TT
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> file</A
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></H1
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><P
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> As your machine gets started, it will need to know the mapping of some hostnames to <SPAN
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CLASS="acronym"
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>IP</SPAN
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> addresses before <SPAN
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CLASS="acronym"
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>DNS</SPAN
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> can be referenced. This mapping is kept in the <TT
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CLASS="filename"
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>/etc/hosts</TT
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> file. In the absence of a name server, any
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network program on your system consults this file to determine the <SPAN
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CLASS="acronym"
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>IP</SPAN
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> address that corresponds to a host name.
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</P
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><P
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> Following is a sample <TT
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CLASS="filename"
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>/etc/hosts</TT
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> file:
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<TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><PRE
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CLASS="programlisting"
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> <SPAN
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CLASS="acronym"
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>IP</SPAN
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>Address Hostname Alias
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127.0.0.1 localhost deep.openna.com
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208.164.186.1 deep.openna.com deep
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208.164.186.2 mail.openna.com mail
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208.164.186.3 web.openna.com web
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</PRE
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></TD
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></TR
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></TABLE
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>
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The leftmost column is the <SPAN
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CLASS="acronym"
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>IP</SPAN
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> address to be resolved. The next column is that host's name. Any subsequent columns are alias for that host. In the second line, for example, the <SPAN
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CLASS="acronym"
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>IP</SPAN
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> address <TT
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CLASS="literal"
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>208.164.186.1</TT
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> is for
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the host <TT
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CLASS="literal"
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>deep.openna.com</TT
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>. Another name for <TT
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CLASS="literal"
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>deep.openna.com</TT
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> is deep.
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</P
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><P
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> After you are finished configuring your networking files, don't forget to restart your network for the changes to take effect.
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<TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><PRE
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CLASS="screen"
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>
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[root@deep] /# /etc/rc.d/init.d/network <B
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CLASS="command"
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>restart</B
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>
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</PRE
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></TD
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></TR
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></TABLE
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>
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<TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><PRE
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CLASS="literallayout"
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> <TT
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CLASS="computeroutput"
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> Setting network parameters [ OK ]
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Bringing up interface lo [ OK ]
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Bringing up interface eth0 [ OK ]
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Bringing up interface eth1 [ OK ]
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</TT
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>
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</PRE
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></TD
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></TR
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></TABLE
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>
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</P
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><DIV
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CLASS="important"
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><BLOCKQUOTE
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CLASS="important"
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><P
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><B
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><SPAN
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CLASS="inlinemediaobject"
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><IMG
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SRC="./images/Important.gif"
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ALT="Important"
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></IMG
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></SPAN
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>: </B
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>
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Time out problems for telnet or ftp connection are often caused by the server trying to resolve the client <SPAN
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CLASS="acronym"
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>IP</SPAN
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> address to a <SPAN
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CLASS="acronym"
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>DNS</SPAN
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> name. Either <SPAN
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CLASS="acronym"
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>DNS</SPAN
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> isn't configured properly on your server or the client machines aren't known to <SPAN
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CLASS="acronym"
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>DNS</SPAN
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>. If you intend to run telnet or ftp services
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on your server, and aren't using <SPAN
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CLASS="acronym"
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>DNS</SPAN
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>, don't forget to add the client machine name and <SPAN
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CLASS="acronym"
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>IP</SPAN
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> in your <TT
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CLASS="filename"
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>/etc/hosts</TT
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> file on the server or you can expect to wait several minutes for the <SPAN
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CLASS="acronym"
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>DNS</SPAN
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> lookup to time out, before you get a <TT
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CLASS="prompt"
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>login:</TT
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> prompt.
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</P
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></BLOCKQUOTE
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="chap9sec94.html"
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>Prev</A
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></TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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>Home</A
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ALIGN="right"
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><A
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HREF="chap9sec96.html"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
|
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ALIGN="left"
|
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VALIGN="top"
|
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>The <TT
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CLASS="filename"
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>/etc/sysctl.conf</TT
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> file</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="file-netfunc.html"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
|
>Config <SPAN
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CLASS="acronym"
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>TCP/IP</SPAN
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> Networking manually -command line</TD
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|
></TR
|
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></TABLE
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></DIV
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></BODY
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> |