67 lines
3.1 KiB
HTML
67 lines
3.1 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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<HTML>
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<HEAD>
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<TITLE>Choosing IP Addresses</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="node116.html">Routing Through a PPP </A>
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<B>Up:</B> <A HREF="node114.html">IP Configuration Options</A>
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<B> Previous:</B> <A HREF="node114.html">IP Configuration Options</A>
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<BR> <P>
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<H2><A NAME="SECTION0010710000">Choosing IP Addresses</A></H2>
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<A NAME="4267"></A>
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<A NAME="4268"></A>
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<A NAME="4269"></A>
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In the example above, we had pppd dial up c3po and establish
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an IP link. No provisions were taken to choose a particular IP-address on
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either end of the link. Instead, we picked vlager's address as the
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local IP-address, and let c3po provide its own. Sometimes, however,
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it is useful to have control over what address is used on one or the other
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end of the link. pppd supports several variations of this.
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<P>
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To ask for particular addresses, you generally provide pppd with
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the following option:
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<Pre>
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local addr:remote addr
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</Pre>
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where local_addr and remote_addr may be specified
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either in dotted quad notation, or as hostnames.<A HREF="footnode.html#4282"><IMG ALIGN=BOTTOM ALT="gif" SRC="foot_motif.gif"></A> This makes pppd attempt to use the first address as its own
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IP-address, and the second as the peer's. If the peer rejects either of
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them during IPCP negotiation, no IP-link will be established.<A HREF="footnode.html#4549"><IMG ALIGN=BOTTOM ALT="gif" SRC="foot_motif.gif"></A>
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<P>
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If you want to set only the local address, but accept any address the
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peer uses, you simply leave out the remote_addr part. For
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instance, to make vlager use the IP-address 130.83.4.27
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instead of its own, you would give it 130.83.4.27: on the
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command line. Similarly, to set the remote address only, you would
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leave the local_addr field blank. By default, pppd
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will then use the address associated with your hostname.
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<P>
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<A NAME="4293"></A>
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Some PPP servers that handle a lot of client sites assign addresses
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dynamically: addresses are assigned to systems only when calling in, and
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are claimed after they have logged off again. When dialing up such a
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server, you must make sure that pppd doesn't request any particular
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IP-address from the server, but rather accept the address the server asks
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you to use. This means that you mustn't specify a local_addr
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argument. In addition, you have to use the noipdefault option,
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which makes pppd wait for the peer to provide the IP-address instead
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of using the local host's address.
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<P>
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<A NAME="4298"></A>
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<P>
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<HR><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="node116.html">Routing Through a PPP </A>
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<B>Up:</B> <A HREF="node114.html">IP Configuration Options</A>
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<B> Previous:</B> <A HREF="node114.html">IP Configuration Options</A>
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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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