Sun Microsystems Sun Workstation 100U System Manager's Manual page 349

Sendmalllnatallatlon .... d Opel'atloa Guide
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5.1.2.1. SmaH atte - eomplete lDIormatloD
A small site (two or three hosts) may and it more reasonable to have complete
inlormation at each host. This would require that each host know exactly where
each network connection is, possibly includinl the Dames 01 each host on that Det-
work.
As
lonl as the site remains small and the the con81uration remains relatitely
static, the update problem wiD probably not be too areat.
1.3.2.3. Slnlle hoat
This is in some sense the trivial case. The only major issue is tryinl to insure
that you don't have to know
too
much about your environment. For example, if
you have a UUCP connection you milht Bnd it uselul to know about the names 01
hosts connected directly to you, but this is really not necessary since this may be
determined from the syntax.
5.3.3. Relevant luuee
The canonical lorm you use should almost certainly be as speei8ed in the Arpanet
protocols RFC819 and RFC822. Copies
01
these RFC's are included on the lendmtJil
tape as doc/rlc819.lpr and tloc/rlc8ee.lp'.
RFC822 describes the lormat 01 the mail messale itself. SendmtJilloUows this
RFC closely, to the extent that many 01 the standards described in this document can
not be changed without changinl the code. In particular, the foUowinl characters have
speeial interpretations:
<>()"\
Any attempt to use these characters lor other than their RFC822 purpose in addresses
is probably doomed to disaster.
RFC819 describes the specifics 01 the domain-baeed addressinl. This is touched
on in RFC822 as well. Essentially each hOBt is liven a name which is a right-to-Iert dot
qualified pseudo-path from a distinluished root. The elements 01 the path need not be
physical hosts; the domain is logical rather than physical. For example, at Berkeley
one legal host is "a.cc.berteley.arpa". Readinl from right to lelt, "arpa" is a top level
domain (related to, but not limited to, the pbysical Arpanet), "berkeley" is both an
Arpanet host and a logical domain which is actually interpreted by a host called ucbvax
(the "major" host ror this domain), "cc" represents tbe Computer Center, (in this case
a strictly logical entity), and "a" is a host in the Computer Center; this particular host
happens to be connected via berknet, the Berkeley network, but other hosts might be
connected via one of two ethernets or some other network.
Be aware when readinl RFC819 that there are a number 01 errors in it.
&.3.4. How to proceed
Once you have decided on a philosophy, it is worth exammmi the available
configuration tables to decide if any or them are close enough to steal major parts or.
Even under the worst of conditions, there is a rair amount of boiler plate that can
be
collected sarely.
The next step
is
to
build ruleset three. This will be the hardest part 01 the job.
Beware of doing too much to the address in this ruleset, since anythinl you do will
reflect through to the messaae.
In
particular, strippinl 01 local domains is best
dererred, since this can leave you with addresses with no domain spec at all. Since
,endmail likes to append the sendinl domain to addresses with no domain, this can
change the semantics 01 addresses. Also
try to avoid lully qualilyiDl domains in this
ruleset. Although technically legal, this can lead to unpleasantly and unnecessarily lonl
addresses reflected into messaaes. The Berkeley conBguration Bles deBne ruleset nine to
qualify domain names and strip local domains. This is called from ruleset zero to let
Version 4.1 Last Mod 8/21/83