Date: Tue, 19 Nov 1996 01:42:07 +0100 (MET) From: J Wunsch <j@uriah.heep.sax.de> To: freebsd-hackers@freebsd.org (FreeBSD hackers) Cc: marcs@znep.com (Marc Slemko) Subject: Re: sendmail without DNS (was: Re: BoS: Exploit for sendmail smtpd bug (ver. 8.7-8.8.2).) Message-ID: <199611190042.BAA03594@uriah.heep.sax.de> In-Reply-To: <Pine.BSF.3.95.961118121318.5700C-100000@alive.ampr.ab.ca> from Marc Slemko at "Nov 18, 96 12:17:21 pm"
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As Marc Slemko wrote:
> I have tried nocanonify, nodns, a service.switch file and perhaps a few
> other things that I can't remember right now, but sendmail still tries to
> do DNS lookups.
You must do something wrong. I'm using a local nameserver, but as you
can see, it's only used for local lookups:
uriah # kill -USR1 `cat /var/run/named.pid `
uriah # echo "hi you" | mail -s "test mail" marcs@znep.com
uriah # kill -USR2 `cat /var/run/named.pid `
uriah # cat /var/tmp/named.run
Debug turned ON, Level 1
datagram from [127.0.0.1].4970, fd 6, len 35; now Tue Nov 19 01:33:38 1996
req: nlookup(uriah.heep.sax.de) id 22463 type=1 class=1
req: found 'uriah.heep.sax.de' as 'uriah.heep.sax.de' (cname=0)
ns_req: answer -> [127.0.0.1].4970 fd=6 id=22463 size=124 Local
datagram from [127.0.0.1].4971, fd 6, len 42; now Tue Nov 19 01:33:38 1996
req: nlookup(1.0.168.192.in-addr.arpa) id 22464 type=12 class=1
req: found '1.0.168.192.in-addr.arpa' as '1.0.168.192.in-addr.arpa' (cname=0)
ns_req: answer -> [127.0.0.1].4971 fd=6 id=22464 size=139 Local
Debug turned OFF
That's a simple turnaround for resolving the local host name. We
can even stop the nameserver just for testing:
uriah # kill -STOP `cat /var/run/named.pid `
uriah # (echo "/bind/s/^/#"; echo "w"; echo "q") | ed /etc/host.conf
105
#bind
106
uriah # echo "hi you" | mail -s "test mail" marcs@znep.com
uriah # mailq
Mail Queue (1 request)
--Q-ID-- --Size-- -----Q-Time----- ------------Sender/Recipient------------
BAA03279* (no control file)
(Well, that's the queue file from my /etc/daily that's just running
right now. Your mail did already go out to the UUCP spool by that
time, no additional delay for nameserver attempts etc.)
uriah # kill -CONT `cat /var/run/named.pid `
This is with no compile-time sendmail trickery, a plain sendmail
compilation from -current (as of a few weeks ago), with the following
.mc file:
include(`../m4/cf.m4')
VERSIONID(`$Id: uriah.mc,v 1.11 1996/04/27 10:15:52 r Exp $')
OSTYPE(bsd4.4)dnl
FEATURE(nodns)dnl
FEATURE(nocanonify)dnl
FEATURE(mailertable)dnl
define(`confMIME_FORMAT_ERRORS', `False')
define(`confMESSAGE_TIMEOUT', `7d/3d')
define(`UUCP_RELAY', sax.sax.de)
define(`UUCP_MAX_SIZE', 200000)
define(`LOCAL_MAILER_ARGS', `mail -b $u')
MAILER(local)dnl
MAILER(smtp)dnl
MAILER(uucp)dnl
Op noreceipts
Cw uriah uriah.sax.de
Cw heep.sax.de
Cw jette jette.sax.de
Cw uriah.UUCP
Cw ppp-uriah.interface-business.de
--
cheers, J"org
joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
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