105 lines
5.1 KiB
HTML
105 lines
5.1 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>Mixing UUCP and RFC-822</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="node194.html">Pathalias and Map File </A>
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<B>Up:</B> <A HREF="node190.html">How does Mail Routing </A>
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<B> Previous:</B> <A HREF="node192.html">Mail Routing in the </A>
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<BR> <P>
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<H2><A NAME="SECTION0015430000">Mixing UUCP and RFC-822</A></H2>
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The best cure against the problems of mail routing in UUCP networks so
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far is the adoption of the domain name system in UUCP networks. Of
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course, you can't query a name server over UUCP. Nevertheless, many
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UUCP sites have formed small domains that coordinate their routing
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internally. In the Maps, these domains announce one or two host as
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their mail gateways, so that there doesn't have to be a map entry for
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each host in the domain. The gateways handle all mail that flows into
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and out of the domain. The routing scheme inside the domain is completely
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invisible to the outside world.
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<P>
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This works very well with the smart-host routing scheme described
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above. Global routing information is maintained by the gateways only;
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minor hosts within a domain will get along with only a small
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hand-written paths file that lists the routes inside their
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domain, and the route to the mail hub. Even the mail gateways
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do not have to have routing information for every single UUCP host in
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the world anymore. Beside the complete routing information for the
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domain they serve, they only need to have routes to entire domains in
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their databases now. For instance, the pathalias entry shown below
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will route all mail for sites in the sub.org domain to
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smurf:
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<PRE>
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.sub.org swim!smurf!%s
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</PRE>
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Any mail addressed to claire@jones.sub.org will be sent to
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swim with an envelope address of smurf!jones!claire.
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<P>
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The hierarchical organization of the domain name space allows mail
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servers to mix more specific routes with less specific ones. For
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instance, a system in France may have specific routes for subdomains
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of fr, but route any mail for hosts in the us domain
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toward some system in the U.S. In this way, domain-based routing (as
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this technique is called) greatly reduces the size of routing databases
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as well as the administrative overhead needed.
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<P>
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The main benefit of using domain names in a UUCP environment, however,
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is that compliance with RFC-822 permits easy gatewaying between UUCP
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networks and the Internet. Many UUCP domains nowadays have a link
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with an Internet gateway that acts as their smart-host. Sending
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messages across the Internet is faster, and routing information is
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much more reliable because Internet hosts can use DNS instead of the
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Usenet Maps.
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<P>
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In order to be reachable from the Internet, UUCP-based domains usually
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have their Internet gateway announce an MX record for them (MX records
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were described above). For instance, assume that moria belongs
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to the orcnet.org domain. gcc2.groucho.edu acts as
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their Internet gateway. moria would therefore use gcc2
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as its smart-host, so that all mail for foreign domains is delivered
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across the Internet. On the other hand, gcc2 would announce an
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MX record for orcnet.org, and deliver all incoming mail for
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orcnet sites to moria.
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<P>
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The only remaining problem is that the UUCP transport programs can't
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deal with fully qualified domain names. Most UUCP suites were
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designed to cope with site names of up to eight characters, some even
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less, and using non-alphanumeric characters such as dots is completely
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out of the question for most.
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<P>
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Therefore, some mapping between RFC-822 names and UUCP hostnames is
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needed. The way this mapping is done is completely
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implementation-dependent. One common way of mapping FQDNs to UUCP
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names is to use the pathalias file for this:
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<PRE>
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moria.orcnet.org ernie!bert!moria!%s
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</PRE>
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This will produce a pure UUCP-style bang path from an address that
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specifies a fully qualified domain name. Some mailers provide a
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special files for this; sendmail, for instance, uses the
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uucpxtable for this.
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<P>
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The reverse transformation (colloquially called domainizing) is
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sometimes required when sending mail from a UUCP network to the
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Internet. As long as the mail sender uses the fully qualified domain
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name in the destination address, this problem can be avoided by not
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removing the domain name from the envelope address when forwarding the
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message to the smart-host. However, there are still some UUCP sites
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that are not part of any domain. They are usually domainized by
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appending the pseudo-domain uucp.
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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="node194.html">Pathalias and Map File </A>
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<B>Up:</B> <A HREF="node190.html">How does Mail Routing </A>
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<B> Previous:</B> <A HREF="node192.html">Mail Routing in the </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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