[comp.mail.sendmail] Hiding the internal network

scott@nastar.UUCP (Scott Barman) (10/20/89)

It took a few days, but I finally conqured sendmail (read: I figured out
enough of it to get done what I needed to) when the System V machine that
was out "gateway" to Usenet died.  Therefore, please bear in mind I am a
sendmail neophyte and I need all the help I can get!

I managed to get sendmail on all our subsidiary machines to pass all
Internet-style addresses it can't resolve on our net to be passed to
the mailhost to send it to the system I have defined as our relay host
(they are on the Internet).  I also figured out how to prevent the "To:"
line from getting rewritten (i.e. put the address specified there).
I even have the "From:" header re-written to look like a uucp address
(we are not an Internet site) before calling uux.

However, we are having problems with names on our internal network
clashing with established names.  When the sendmail on the mailhost gets
the return address (and I will use mine as an example), it looks like
"scott@nascom.nastar.uucp".  Before sending it to the relay host, it will
rewrite it as "nastar!nascom!scott"--which is correct, but the system
"nascom" is already in the Usenet maps.  What is happening is that some
folks who run pathalias and/or Smail are having these programs route
mail to me to the wrong system.

What I would like to do is to (some how) tell sendmail that internal
names should be written as mailhost!user (as in nastar!scott)--which
will work since I have (and will continue to have) everyone in our
YP mail.aliases map.  Is there any way to do this?

Any and all help would be greatly appreciated!

-- 
scott barman
emory!nastar!scott	<-- please note new address

avolio@decuac.DEC.COM (Frederick M. Avolio) (10/20/89)

Sure..

This is how I do it.

1. I have a list of hosts I want to hide.  It should be obvious (okay, we're
talking sendmail.c fhere, I know) how to do this for ALL hosts in the
domain

FH/etc/hosts.hide

2. In my tcpip mailer subset for sender (S=) I have these lines to
rewrite the sender info:

R$+<@$=H.$D>$*          $1<@$j>$3       hide hiddenhosts.$D under $j
R$+<@$=H.$+.$D>$*               $1<@$j>$4       hide hiddenhosts.$D under $j

3. I have the same under my uucp mailer Sender ruleset.  I do not
rewrite user@decuac.dec.com to decuac!user, but if you want you
can (and probably do) do this.  Just out the RUlesets in #2 above
where that rewrite is done.

Fred