Re: Securing Sendmail 8.11.6-23 from spammers

On Wed Mar 05 2003 at 20:19, gti617 wrote:

> 1) I came up with the conclusion that sendmail 8.11.6 works; when

Sendmail has done very serious work all over the internet for lots
of people (including myself).  Of course it works.

> sendmail.cf is generated by "linuxconf". My users can send and receive

BIG WARNING: linuxconf is a total crock and will end up destroying
things on your system.  Been there, done that.  Redhat have pulled
it from later distributions, and for good reason.  Take some good
advice - remove it immediately.  If you don't take heed of this
advice, then when things break don't come crying here.  Same with
webmin, I've had some particularly bad experiences with that too.

> e-mails with out any problems. At that point it does not matter what the
> contents of /etc/mail/access file is; they could be all REJECTs or RELAYs or
> anything in between (yes I generated access.db file by makemap hash and

ohgohd, that's a bad attitude... it DOES matter what goes into that
file!

Remember that you are asking here how to secure sendmail from being
abused by spammers.  We are trying to show you what to do.  And it
is obvious that you are doing something wrong ("user error").

> restarted sendmail). Further checking the relay test by relays.osirusoft.com
> company tells me that I have a beautiful open relay server (SPAMMERS: Come
> and use my server!).

See?  Not good.

RELAY for localhost and your local network(s), and for noone else.

> 2) When I create sendmail.cf file by "m4 /etc/mail/sendmail.mc >
> /etc/sendmail.cf" command. Non of my pop or normal users can send or receive
> e-mails. But the relay problem would go away ( My server will not relay)
> Using the following code.

Collection of email (via pop or imap) has nothing to do with sendmail.

But if they cannot send (relay) email through you, then you are
denying them access... so add proper entries that will allow them to
do that.

> So where am I right now?  No where. I am headed to a bookstore. I am where I
> started from.  I wish someone from RedHat would be HERO and read this
> message and solve the problem of a lot of People.  Sincerely -- Kevin

I've answered your thread three times now, and I'm not the only one.
We are all heros here.

And the only person who seems to be having hassles with this is
yourself.

> ----- access file contained

> localhost.localdomain	RELAY
> localhost	RELAY
> 127.0.0.1	RELAY
> ZZZ.com	RELAY
> @ZZZ.com	RELAY
> [email protected]	RELAY

Did you read the sendmail-cf README file yet?

I assume that your DNS can resolve the "ZZZ.com" domain into
something sensible.

But it would be better to add IP addresses (or C-class subnets)
rather than domain names.

BTW, "[email protected]" literally means "@zzz.com" - the IP address of
the remote box MUST resolve to that exact name in the DNS.  Try it
like this for hostnames in that domain:

.zzz.com	RELAY

> ----- sendmail.mc file containes

yeah, seen this at least three times now...

> -->> after editing the /etc/mail/senmail.mc file, I type the following to
> come up with /etc/sendmail.cf file.
> # m4 /etc/mail/sendmail.mc > /etc/sendmail.cf
> 
> -->> Then I restart the sendmail service by typing the following:
> # /etc/rc5.d/S80sendmail restart

> --> Then I can neither send nor receive any e-mails.

Send from where?

This isn't as complicated as you make it out to be... when you find
your mistake, you'll probably kick yourself.

Cheers
Tony