86 lines
3.6 KiB
HTML
86 lines
3.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
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<!--Converted with LaTeX2HTML 96.1-c (Feb 29, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds -->
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!-- Updated Thu Jul 11 22:25:23 MET DST 1996 by tony@iaehv.iaehv.nl
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<HTML>
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<HEAD>
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<TITLE>The host.conf File</TITLE>
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</HEAD>
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<BODY LANG="EN">
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<A HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <BR>
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<B> Next:</B> <A HREF="node83.html">Resolver Environment Variables</A>
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<B>Up:</B> <A HREF="node81.html">The Resolver Library</A>
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<B> Previous:</B> <A HREF="node81.html">The Resolver Library</A>
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<BR> <P>
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<H2><A NAME="SECTION008110000">The host.conf File</A></H2>
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The central file that controls your resolver setup is host.conf.
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It resides in /etc and tells the resolver which services
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to use, and in what order.
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<P>
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Options in host.conf must occur on separate lines. Fields may be
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separated by white space (spaces or tabs). A hash sign (#)
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introduces a comment that extends to the next newline.
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<P>
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The following options are available:
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<dl>
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<dt><b> order </b><dd> This determines the order in which the resolving services are tried. Valid options are :
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<ul><li><b>bind</b> for querying the name server
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<li><b>hosts</b> for lookups in /etc/hosts
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<li><b>nis</b> for NIS lookups.
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</ul>
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<dd> Any or all of them may be specified. The order in which they
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appear on the line determines the order in which the respective
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services are tried.
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<dt><b>multi</b><dd> Takes on or off as options. This determines if a host in
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/etc/hosts is allowed to have several IP addresses, which is
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usually referred to as being ``multi-homed''. This flag has no
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effect on DNS or NIS queries.
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<dt><b> nospoof</b><dd> As explained in the previous chapter, DNS allows you to find
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the hostname belonging to an IP address by using the in-
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addr.arpa domain. Attempts by name servers to supply a false
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hostname are called ``spoofing''. To guard against this, the
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resolver may be configured to check if the original IP address
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is in fact associated with the hostname obtained. If not, the
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name is rejected and an error returned. This behavior is
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turned on by setting nospoof on.
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<dt><b> alert </b><dd>This option takes on or off as arguments. If it is turned on,
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any spoof attempts (see above) will cause the resolver to log
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a message to the syslog facility.
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<dt><b> trim</b><dd> This option takes a domain name as an argument, which will be
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removed from hostnames before lookup. This is useful for hosts
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entries, where you might only want to specify hostnames with-
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out local domain. A lookup of a host with the local domain
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name appended will have this removed, thus allowing the lookup
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in /etc/hosts to succeed.
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trim options accumulate, making it possible to consider
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your host as being local to several domains.
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</dl>
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A sample file for vlager is shown below:
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<pre>
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# /etc/host.conf
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# We have named running, but no NIS (yet)
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order bind hosts
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# Allow multiple addrs
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multi on
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# Guard against spoof attempts
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nospoof on
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# Trim local domain (not really necessary).
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trim vbrew.com.
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</pre>
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<hr>
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<P><ADDRESS>
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<I>Andrew Anderson <BR>
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Thu Mar 7 23:22:06 EST 1996</I>
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</ADDRESS>
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</BODY>
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</HTML>
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