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Sendmail questions.

Posted on 1999-09-20
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Last Modified: 2013-12-15
Hi!

I just tried nessus against my machine to find out if I had any security holes.

I got this:
Sendmail supports the EHLO greetings
which means that it supports the ESMTP, which may be the source of additional security flaws that can be used by attackers.
Solutions: dissable this feture in sendmail.conf

Sendmail allows the EXPN command to be preformed, (as well as  VFRY) This can give away some intresting information to an intruder.
Solution: edit sendmail.conf

The remote sendmail allows mail relaying. Spamers can send mail using this host.

How can I fix those things?


Im using sendmail-8.9.3-11mdk






Here is my sendmail.conf


#
# Copyright (c) 1998 Sendmail, Inc.  All rights reserved.
# Copyright (c) 1983, 1995 Eric P. Allman.  All rights reserved.
# Copyright (c) 1988, 1993
#      The Regents of the University of California.  All rights reserved.
#
# By using this file, you agree to the terms and conditions set
# forth in the LICENSE file which can be found at the top level of
# the sendmail distribution.
#
#

######################################################################
######################################################################
#####
#####            SENDMAIL CONFIGURATION FILE
#####
##### built by root@Homie.Netpirate.ORG on Thu Jul 8 01:24:40 MDT 1999
##### in /usr/src/RPM/BUILD/sendmail-8.9.3/cf/cf
##### using ../ as configuration include directory
#####
######################################################################
######################################################################

#####  @(#)cfhead.m4      8.23 (Berkeley) 10/6/1998  #####
#####  @(#)cf.m4      8.29 (Berkeley) 5/19/1998  #####



#####  @(#)linux.m4      8.7 (Berkeley) 5/19/1998  #####
# #








#####  @(#)smrsh.m4      8.8 (Berkeley) 5/19/1998  #####


#####  @(#)virtusertable.m4      8.8 (Berkeley) 10/6/1998  #####


#####  @(#)redirect.m4      8.10 (Berkeley) 5/19/1998  #####


#####  @(#)always_add_domain.m4      8.6 (Berkeley) 5/19/1998  #####


#####  @(#)use_cw_file.m4      8.6 (Berkeley) 5/19/1998  #####



#####  @(#)local_procmail.m4      8.11 (Berkeley) 5/19/1998  #####




#####  @(#)access_db.m4      8.8 (Berkeley) 5/19/1998  #####


#####  @(#)blacklist_recipients.m4      8.9 (Berkeley) 5/19/1998  #####



#####  @(#)proto.m4      8.243 (Berkeley) 2/2/1999  #####


# level 8 config file format
V8/Berkeley

# override file safeties - setting this option compromises system security
# need to set this now for the sake of class files
#O DontBlameSendmail=safe

##################
#   local info   #
##################

Cwlocalhost
# file containing names of hosts for which we receive email
Fw/etc/sendmail.cw

# my official domain name
# ... define this only if sendmail cannot automatically determine your domain
#Dj$w.Foo.COM


CP.

# "Smart" relay host (may be null)
DS


# operators that cannot be in local usernames (i.e., network indicators)
CO @ % !

# a class with just dot (for identifying canonical names)
C..

# a class with just a left bracket (for identifying domain literals)
C[[






# Virtual user table (maps incoming users)
Kvirtuser hash -o /etc/mail/virtusertable

# Access list database (for spam stomping)
Kaccess hash -o /etc/mail/access


# Resolve map (to check if a host exists in check_mail)
Kresolve host -a<OK> -T<TEMP>

# Hosts that will permit relaying ($=R)
FR-o /etc/mail/relay-domains

# who I send unqualified names to (null means deliver locally)
DR

# who gets all local email traffic ($R has precedence for unqualified names)
DH

# dequoting map
Kdequote dequote

# class E: names that should be exposed as from this host, even if we masquerade
# class L: names that should be delivered locally, even if we have a relay
# class M: domains that should be converted to $M
#CL root
CE root

# who I masquerade as (null for no masquerading) (see also $=M)
DM

# my name for error messages
DnMAILER-DAEMON


CPREDIRECT

# Configuration version number
DZ8.9.3


###############
#   Options   #
###############

# strip message body to 7 bits on input?
O SevenBitInput=False

# 8-bit data handling
O EightBitMode=pass8


# wait for alias file rebuild (default units: minutes)
O AliasWait=10

# location of alias file
O AliasFile=/etc/aliases

# minimum number of free blocks on filesystem
O MinFreeBlocks=100

# maximum message size
#O MaxMessageSize=1000000

# substitution for space (blank) characters
O BlankSub=.

# avoid connecting to "expensive" mailers on initial submission?
O HoldExpensive=False

# checkpoint queue runs after every N successful deliveries
#O CheckpointInterval=10

# default delivery mode
O DeliveryMode=background

# automatically rebuild the alias database?
O AutoRebuildAliases=

# error message header/file
#O ErrorHeader=/etc/sendmail.oE

# error mode
#O ErrorMode=print

# save Unix-style "From_" lines at top of header?
#O SaveFromLine

# temporary file mode
O TempFileMode=0600

# match recipients against GECOS field?
#O MatchGECOS

# maximum hop count
#O MaxHopCount=17

# location of help file
O HelpFile=/usr/lib/sendmail.hf

# ignore dots as terminators in incoming messages?
#O IgnoreDots

# name resolver options
#O ResolverOptions=+AAONLY

# deliver MIME-encapsulated error messages?
O SendMimeErrors=True

# Forward file search path
O ForwardPath=$z/.forward.$w:$z/.forward

# open connection cache size
O ConnectionCacheSize=2

# open connection cache timeout
O ConnectionCacheTimeout=5m

# persistent host status directory
#O HostStatusDirectory=.hoststat

# single thread deliveries (requires HostStatusDirectory)?
#O SingleThreadDelivery

# use Errors-To: header?
O UseErrorsTo=False

# log level
O LogLevel=9

# send to me too, even in an alias expansion?
#O MeToo

# verify RHS in newaliases?
O CheckAliases=False

# default messages to old style headers if no special punctuation?
O OldStyleHeaders=True

# SMTP daemon options
#O DaemonPortOptions=Port=esmtp

# privacy flags
O PrivacyOptions=authwarnings

# who (if anyone) should get extra copies of error messages
#O PostMasterCopy=Postmaster

# slope of queue-only function
#O QueueFactor=600000

# queue directory
O QueueDirectory=/var/spool/mqueue

# timeouts (many of these)
#O Timeout.initial=5m
O Timeout.connect=1m
#O Timeout.iconnect=5m
#O Timeout.helo=5m
#O Timeout.mail=10m
#O Timeout.rcpt=1h
#O Timeout.datainit=5m
#O Timeout.datablock=1h
#O Timeout.datafinal=1h
#O Timeout.rset=5m
#O Timeout.quit=2m
#O Timeout.misc=2m
#O Timeout.command=1h
#O Timeout.ident=30s
#O Timeout.fileopen=60s
O Timeout.queuereturn=5d
#O Timeout.queuereturn.normal=5d
#O Timeout.queuereturn.urgent=2d
#O Timeout.queuereturn.non-urgent=7d
O Timeout.queuewarn=4h
#O Timeout.queuewarn.normal=4h
#O Timeout.queuewarn.urgent=1h
#O Timeout.queuewarn.non-urgent=12h
#O Timeout.hoststatus=30m

# should we not prune routes in route-addr syntax addresses?
#O DontPruneRoutes

# queue up everything before forking?
O SuperSafe=True

# status file
O StatusFile=/var/log/sendmail.st

# time zone handling:
#  if undefined, use system default
#  if defined but null, use TZ envariable passed in
#  if defined and non-null, use that info
#O TimeZoneSpec=

# default UID (can be username or userid:groupid)
O DefaultUser=8:12

# list of locations of user database file (null means no lookup)
#O UserDatabaseSpec=/etc/userdb

# fallback MX host
#O FallbackMXhost=fall.back.host.net

# if we are the best MX host for a site, try it directly instead of config err
O TryNullMXList=true

# load average at which we just queue messages
#O QueueLA=8

# load average at which we refuse connections
#O RefuseLA=12

# maximum number of children we allow at one time
#O MaxDaemonChildren=12

# maximum number of new connections per second
#O ConnectionRateThrottle=3

# work recipient factor
#O RecipientFactor=30000

# deliver each queued job in a separate process?
#O ForkEachJob

# work class factor
#O ClassFactor=1800

# work time factor
#O RetryFactor=90000

# shall we sort the queue by hostname first?
#O QueueSortOrder=priority

# minimum time in queue before retry
#O MinQueueAge=30m

# default character set
#O DefaultCharSet=iso-8859-1

# service switch file (ignored on Solaris, Ultrix, OSF/1, others)
#O ServiceSwitchFile=/etc/service.switch

# hosts file (normally /etc/hosts)
#O HostsFile=/etc/hosts

# dialup line delay on connection failure
#O DialDelay=10s

# action to take if there are no recipients in the message
#O NoRecipientAction=add-to-undisclosed

# chrooted environment for writing to files
#O SafeFileEnvironment=/arch

# are colons OK in addresses?
#O ColonOkInAddr

# how many jobs can you process in the queue?
#O MaxQueueRunSize=10000

# shall I avoid expanding CNAMEs (violates protocols)?
#O DontExpandCnames

# SMTP initial login message (old $e macro)
O SmtpGreetingMessage=$j Sendmail $v/$Z; $b

# UNIX initial From header format (old $l macro)
O UnixFromLine=From $g  $d

# From: lines that have embedded newlines are unwrapped onto one line
#O SingleLineFromHeader=False

# Allow HELO SMTP command that does not include a host name
#O AllowBogusHELO=False

# Characters to be quoted in a full name phrase (@,;:\()[] are automatic)
#O MustQuoteChars=.

# delimiter (operator) characters (old $o macro)
O OperatorChars=.:%@!^/[]+

# shall I avoid calling initgroups(3) because of high NIS costs?
#O DontInitGroups

# are group-writable :include: and .forward files (un)trustworthy?
#O UnsafeGroupWrites

# where do errors that occur when sending errors get sent?
#O DoubleBounceAddress=postmaster

# what user id do we assume for the majority of the processing?
#O RunAsUser=sendmail

# maximum number of recipients per SMTP envelope
#O MaxRecipientsPerMessage=100

# shall we get local names from our installed interfaces?
O DontProbeInterfaces=true






###########################
#   Message precedences   #
###########################

Pfirst-class=0
Pspecial-delivery=100
Plist=-30
Pbulk=-60
Pjunk=-100

#####################
#   Trusted users   #
#####################

# this is equivalent to setting class "t"
#Ft/etc/sendmail.ct
Troot
Tdaemon
Tuucp

#########################
#   Format of headers   #
#########################

H?P?Return-Path: <$g>
HReceived: $?sfrom $s $.$?_($?s$|from $.$_)
      $.by $j ($v/$Z)$?r with $r$. id $i$?u
      for $u; $|;
      $.$b
H?D?Resent-Date: $a
H?D?Date: $a
H?F?Resent-From: $?x$x <$g>$|$g$.
H?F?From: $?x$x <$g>$|$g$.
H?x?Full-Name: $x
# HPosted-Date: $a
# H?l?Received-Date: $b
H?M?Resent-Message-Id: <$t.$i@$j>
H?M?Message-Id: <$t.$i@$j>
#
######################################################################
######################################################################
#####
#####                  REWRITING RULES
#####
######################################################################
######################################################################

############################################
###  Ruleset 3 -- Name Canonicalization  ###
############################################
S3

# handle null input (translate to <@> special case)
R$@                  $@ <@>

# strip group: syntax (not inside angle brackets!) and trailing semicolon
R$*                  $: $1 <@>                  mark addresses
R$* < $* > $* <@>      $: $1 < $2 > $3                  unmark <addr>
R@ $* <@>            $: @ $1                        unmark @host:...
R$* :: $* <@>            $: $1 :: $2                  unmark node::addr
R:include: $* <@>      $: :include: $1                  unmark :include:...
R$* [ $* : $* ] <@>      $: $1 [ $2 : $3 ]            unmark IPv6 addrs
R$* : $* [ $* ]            $: $1 : $2 [ $3 ] <@>            remark if leading colon
R$* : $* <@>            $: $2                        strip colon if marked
R$* <@>                  $: $1                        unmark
R$* ;                     $1                        strip trailing semi
R$* < $* ; >               $1 < $2 >                  bogus bracketed semi

# null input now results from list:; syntax
R$@                  $@ :; <@>

# strip angle brackets -- note RFC733 heuristic to get innermost item
R$*                  $: < $1 >                  housekeeping <>
R$+ < $* >               < $2 >                  strip excess on left
R< $* > $+               < $1 >                  strip excess on right
R<>                  $@ < @ >                  MAIL FROM:<> case
R< $+ >                  $: $1                        remove housekeeping <>

# make sure <@a,@b,@c:user@d> syntax is easy to parse -- undone later
R@ $+ , $+            @ $1 : $2                  change all "," to ":"

# localize and dispose of route-based addresses
R@ $+ : $+            $@ $>96 < @$1 > : $2            handle <route-addr>

# find focus for list syntax
R $+ : $* ; @ $+      $@ $>96 $1 : $2 ; < @ $3 >      list syntax
R $+ : $* ;            $@ $1 : $2;                  list syntax

# find focus for @ syntax addresses
R$+ @ $+            $: $1 < @ $2 >                  focus on domain
R$+ < $+ @ $+ >            $1 $2 < @ $3 >                  move gaze right
R$+ < @ $+ >            $@ $>96 $1 < @ $2 >            already canonical

# do some sanity checking
R$* < @ $* : $* > $*      $1 < @ $2 $3 > $4            nix colons in addrs

# convert old-style addresses to a domain-based address
R$- ! $+            $@ $>96 $2 < @ $1 .UUCP >      resolve uucp names
R$+ . $- ! $+            $@ $>96 $3 < @ $1 . $2 >            domain uucps
R$+ ! $+            $@ $>96 $2 < @ $1 .UUCP >      uucp subdomains

# if we have % signs, take the rightmost one
R$* % $*            $1 @ $2                        First make them all @s.
R$* @ $* @ $*            $1 % $2 @ $3                  Undo all but the last.
R$* @ $*            $@ $>96 $1 < @ $2 >            Insert < > and finish

# else we must be a local name
R$*                  $@ $>96 $1


################################################
###  Ruleset 96 -- bottom half of ruleset 3  ###
################################################

S96

# handle special cases for local names
R$* < @ localhost > $*            $: $1 < @ $j . > $2            no domain at all
R$* < @ localhost . $m > $*      $: $1 < @ $j . > $2            local domain
R$* < @ localhost . UUCP > $*      $: $1 < @ $j . > $2            .UUCP domain
R$* < @ [ $+ ] > $*            $: $1 < @@ [ $2 ] > $3            mark [a.b.c.d]
R$* < @@ $=w > $*            $: $1 < @ $j . > $3            self-literal
R$* < @@ $+ > $*            $@ $1 < @ $2 > $3            canon IP addr





# if really UUCP, handle it immediately

# try UUCP traffic as a local address
R$* < @ $+ . UUCP > $*            $: $1 < @ $[ $2 $] . UUCP . > $3
R$* < @ $+ . . UUCP . > $*      $@ $1 < @ $2 . > $3

# pass to name server to make hostname canonical
R$* < @ $* $~P > $*            $: $1 < @ $[ $2 $3 $] > $4

# local host aliases and pseudo-domains are always canonical
R$* < @ $=w > $*            $: $1 < @ $2 . > $3
R$* < @ $j > $*                  $: $1 < @ $j . > $2
R$* < @ $=M > $*            $: $1 < @ $2 . > $3
R$* < @ $* $=P > $*            $: $1 < @ $2 $3 . > $4
R$* < @ $* . . > $*            $1 < @ $2 . > $3


##################################################
###  Ruleset 4 -- Final Output Post-rewriting  ###
##################################################
S4

R$* <@>                  $@                        handle <> and list:;

# strip trailing dot off possibly canonical name
R$* < @ $+ . > $*      $1 < @ $2 > $3

# eliminate internal code -- should never get this far!
R$* < @ *LOCAL* > $*      $1 < @ $j > $2

# externalize local domain info
R$* < $+ > $*            $1 $2 $3                  defocus
R@ $+ : @ $+ : $+      @ $1 , @ $2 : $3            <route-addr> canonical
R@ $*                  $@ @ $1                        ... and exit

# UUCP must always be presented in old form
R$+ @ $- . UUCP            $2!$1                        u@h.UUCP => h!u

# delete duplicate local names
R$+ % $=w @ $=w            $1 @ $2                        u%host@host => u@host



##############################################################
###   Ruleset 97 -- recanonicalize and call ruleset zero   ###
###               (used for recursive calls)               ###
##############################################################

S97
R$*                  $: $>3 $1
R$*                  $@ $>0 $1


######################################
###   Ruleset 0 -- Parse Address   ###
######################################

S0

R$*                  $: $>Parse0 $1            initial parsing
R<@>                  $#local $: <@>            special case error msgs
R$*                  $: $>98 $1            handle local hacks
R$*                  $: $>Parse1 $1            final parsing

#
#  Parse0 -- do initial syntax checking and eliminate local addresses.
#      This should either return with the (possibly modified) input
#      or return with a #error mailer.  It should not return with a
#      #mailer other than the #error mailer.
#

SParse0
R<@>                  $@ <@>                  special case error msgs
R$* : $* ; <@>            $#error $@ 5.1.3 $: "List:; syntax illegal for recipient addresses"
#R@ <@ $* >            < @ $1 >            catch "@@host" bogosity
R<@ $+>                  $#error $@ 5.1.3 $: "User address required"
R$*                  $: <> $1
R<> $* < @ [ $+ ] > $*      $1 < @ [ $2 ] > $3
R<> $* <$* : $* > $*      $#error $@ 5.1.3 $: "Colon illegal in host name part"
R<> $*                  $1
R$* < @ . $* > $*      $#error $@ 5.1.2 $: "Invalid host name"
R$* < @ $* .. $* > $*      $#error $@ 5.1.2 $: "Invalid host name"

# now delete the local info -- note $=O to find characters that cause forwarding
R$* < @ > $*            $@ $>Parse0 $>3 $1            user@ => user
R< @ $=w . > : $*      $@ $>Parse0 $>3 $2            @here:... -> ...
R$- < @ $=w . >            $: $(dequote $1 $) < @ $2 . >      dequote "foo"@here
R< @ $+ >            $#error $@ 5.1.3 $: "User address required"
R$* $=O $* < @ $=w . >      $@ $>Parse0 $>3 $1 $2 $3      ...@here -> ...
R$-                   $: $(dequote $1 $) < @ *LOCAL* >      dequote "foo"
R< @ *LOCAL* >            $#error $@ 5.1.3 $: "User address required"
R$* $=O $* < @ *LOCAL* >
                  $@ $>Parse0 $>3 $1 $2 $3      ...@*LOCAL* -> ...
R$* < @ *LOCAL* >      $: $1

#
#  Parse1 -- the bottom half of ruleset 0.
#

SParse1
# handle numeric address spec
R$* < @ [ $+ ] > $*      $: $>98 $1 < @ [ $2 ] > $3      numeric internet spec
R$* < @ [ $+ ] > $*      $#esmtp $@ [$2] $: $1 < @ [$2] > $3      still numeric: send

# handle virtual users
R$+ < @ $=w . >       $: < $(virtuser $1 @ $2 $@ $1 $: @ $) > $1 < @ $2 . >
R<@> $+ + $* < @ $* . >
                  $: < $(virtuser $1 + * @ $3 $@ $1 $: @ $) > $1 + $2 < @ $3 . >
R<@> $+ + $* < @ $* . >
                  $: < $(virtuser $1 @ $3 $@ $1 $: @ $) > $1 + $2 < @ $3 . >
R<@> $+ < @ $+ . >      $: < $(virtuser @ $2 $@ $1 $: @ $) > $1 < @ $2 . >
R<@> $+                  $: $1
R< error : $- $+ > $*       $#error $@ $(dequote $1 $) $: $2
R< $+ > $+ < @ $+ >      $: $>97 $1

# short circuit local delivery so forwarded email works
R$=L < @ $=w . >      $#local $: @ $1            special local names
R$+ < @ $=w . >            $#local $: $1                  regular local name


# resolve remotely connected UUCP links (if any)

# resolve fake top level domains by forwarding to other hosts



# pass names that still have a host to a smarthost (if defined)
R$* < @ $* > $*            $: $>95 < $S > $1 < @ $2 > $3      glue on smarthost name

# deal with other remote names
R$* < @$* > $*            $#esmtp $@ $2 $: $1 < @ $2 > $3            user@host.domain

# handle locally delivered names
R$=L                  $#local $: @ $1                  special local names
R$+                  $#local $: $1                  regular local names

###########################################################################
###   Ruleset 5 -- special rewriting after aliases have been expanded   ###
###########################################################################

S5

# deal with plussed users so aliases work nicely
R$+ + *                  $#local $@ $&h $: $1
R$+ + $*            $#local $@ + $2 $: $1 + *

# prepend an empty "forward host" on the front
R$+                  $: <> $1


# see if we have a relay or a hub
R< > $+                  $: < $H > $1                  try hub
R< > $+                  $: < $R > $1                  try relay
R< > $+                  $: < > < $1 $&h >            nope, restore +detail
R< > < $+ + $* > $*         < > < $1 > + $2 $3            find the user part
R< > < $+ > + $*      $#local $@ $2 $: @ $1            strip the extra +
R< > < $+ >            $@ $1                        no +detail
R$+                  $: $1 <> $&h                  add +detail back in
R$+ <> + $*            $: $1 + $2                  check whether +detail
R$+ <> $*            $: $1                        else discard
R< local : $* > $*      $: $>95 < local : $1 > $2      no host extension
R< error : $* > $*      $: $>95 < error : $1 > $2      no host extension
R< $- : $+ > $+            $: $>95 < $1 : $2 > $3 < @ $2 >
R< $+ > $+            $@ $>95 < $1 > $2 < @ $1 >


###################################################################
###  Ruleset 95 -- canonify mailer:[user@]host syntax to triple      ###
###################################################################

S95
R< > $*                        $@ $1                  strip off null relay
R< error : $- $+ > $*            $#error $@ $(dequote $1 $) $: $2
R< local : $* > $*            $>CanonLocal < $1 > $2
R< $- : $+ @ $+ > $*<$*>$*      $# $1 $@ $3 $: $2<@$3>      use literal user
R< $- : $+ > $*                  $# $1 $@ $2 $: $3      try qualified mailer
R< $=w > $*                  $@ $2                  delete local host
R< $+ > $*                  $#relay $@ $1 $: $2      use unqualified mailer

###################################################################
###  Ruleset CanonLocal -- canonify local: syntax            ###
###################################################################

SCanonLocal
# strip local host from routed addresses
R< $* > < @ $+ > : $+            $@ $>97 $3
R< $* > $+ $=O $+ < @ $+ >      $@ $>97 $2 $3 $4

# strip trailing dot from any host name that may appear
R< $* > $* < @ $* . >            $: < $1 > $2 < @ $3 >

# handle local: syntax -- use old user, either with or without host
R< > $* < @ $* > $*            $#local $@ $1@$2 $: $1
R< > $+                        $#local $@ $1    $: $1

# handle local:user@host syntax -- ignore host part
R< $+ @ $+ > $* < @ $* >      $: < $1 > $3 < @ $4 >

# handle local:user syntax
R< $+ > $* <@ $* > $*            $#local $@ $2@$3 $: $1
R< $+ > $*                   $#local $@ $2    $: $1

###################################################################
###  Ruleset 93 -- convert header names to masqueraded form      ###
###################################################################

S93


# special case the users that should be exposed
R$=E < @ *LOCAL* >      $@ $1 < @ $j . >            leave exposed
R$=E < @ $=M . >      $@ $1 < @ $2 . >
R$=E < @ $=w . >      $@ $1 < @ $2 . >

# handle domain-specific masquerading
R$* < @ $=M . > $*      $: $1 < @ $2 . @ $M > $3      convert masqueraded doms
R$* < @ $=w . > $*      $: $1 < @ $2 . @ $M > $3
R$* < @ *LOCAL* > $*      $: $1 < @ $j . @ $M > $2
R$* < @ $+ @ > $*      $: $1 < @ $2 > $3            $M is null
R$* < @ $+ @ $+ > $*      $: $1 < @ $3 . > $4            $M is not null

###################################################################
###  Ruleset 94 -- convert envelope names to masqueraded form      ###
###################################################################

S94
R$* < @ *LOCAL* > $*      $: $1 < @ $j . > $2

###################################################################
###  Ruleset 98 -- local part of ruleset zero (can be null)      ###
###################################################################

S98

# addresses sent to foo@host.REDIRECT will give a 551 error code
R$* < @ $+ .REDIRECT. >            $: $1 < @ $2 . REDIRECT . > < ${opMode} >
R$* < @ $+ .REDIRECT. > <i>      $: $1 < @ $2 . REDIRECT. >
R$* < @ $+ .REDIRECT. > < $- >      $# error $@ 5.1.1 $: "551 User has moved; please try " <$1@$2>


######################################################################
###  LookUpDomain -- search for domain in access database
###
###      Parameters:
###            <$1> -- key (domain name)
###            <$2> -- default (what to return if not found in db)
###            <$3> -- passthru (additional data passed unchanged through)
######################################################################

SLookUpDomain
R<$+> <$+> <$*>            $: < $(access $1 $: ? $) > <$1> <$2> <$3>
R<?> <$+.$+> <$+> <$*>      $@ $>LookUpDomain <$2> <$3> <$4>
R<?> <$+> <$+> <$*>      $@ <$2> <$3>
R<$*> <$+> <$+> <$*>      $@ <$1> <$4>

######################################################################
###  LookUpAddress -- search for host address in access database
###
###      Parameters:
###            <$1> -- key (dot quadded host address)
###            <$2> -- default (what to return if not found in db)
###            <$3> -- passthru (additional data passed through)
######################################################################

SLookUpAddress
R<$+> <$+> <$*>            $: < $(access $1 $: ? $) > <$1> <$2> <$3>
R<?> <$+.$-> <$+> <$*>      $@ $>LookUpAddress <$1> <$3> <$4>
R<?> <$+> <$+> <$*>      $@ <$2> <$3>
R<$*> <$+> <$+> <$*>      $@ <$1> <$4>

######################################################################
###  CanonAddr --      Convert an address into a standard form for
###                  relay checking.  Route address syntax is
###                  crudely converted into a %-hack address.
###
###      Parameters:
###            $1 -- full recipient address
###
###      Returns:
###            parsed address, not in source route form
######################################################################

SCanonAddr
R$*                  $: $>Parse0 $>3 $1      make domain canonical
R< @ $+ > : $* @ $*      < @ $1 > : $2 % $3      change @ to % in src route
R$* < @ $+ > : $* : $*      $3 $1 < @ $2 > : $4      change to % hack.
R$* < @ $+ > : $*      $3 $1 < @ $2 >

######################################################################
###  ParseRecipient --      Strip off hosts in $=R as well as possibly
###                  $* $=m or the access database.
###                  Check user portion for host separators.
###
###      Parameters:
###            $1 -- full recipient address
###
###      Returns:
###            parsed, non-local-relaying address
######################################################################

SParseRecipient
R$*                        $: <?> $>CanonAddr $1
R<?> $* < @ $* . >            <?> $1 < @ $2 >                  strip trailing dots
R<?> $- < @ $* >            $: <?> $(dequote $1 $) < @ $2 >      dequote local part

# if no $=O character, no host in the user portion, we are done
R<?> $* $=O $* < @ $* >            $: <NO> $1 $2 $3 < @ $4>
R<?> $*                        $@ $1



R<NO> $* < @ $* $=R >            $: <RELAY> $1 < @ $2 $3 >
R<NO> $* < @ $+ >            $: $>LookUpDomain <$2> <NO> <$1 < @ $2 >>
R<$+> <$+>                  $: <$1> $2

R<RELAY> $* < @ $* >            $@ $>ParseRecipient $1
R<$-> $*                  $@ $2

######################################################################
###  check_relay -- check hostname/address on SMTP startup
######################################################################

SLocal_check_relay
Scheck_relay
R$*                  $: $1 $| $>"Local_check_relay" $1
R$* $| $* $| $#$*      $#$3
R$* $| $* $| $*            $@ $>"Basic_check_relay" $1 $| $2

SBasic_check_relay
# check for deferred delivery mode
R$*                  $: < ${deliveryMode} > $1
R< d > $*            $@ deferred
R< $* > $*            $: $2

R$+ $| $+            $: $>LookUpDomain < $1 > <?> < $2 >
R<?> < $+ >            $: $>LookUpAddress < $1 > <?> < $1 >
R<?> < $+ >            $: $1
R<OK> < $* >            $@ OK
R<RELAY> < $* >            $@ RELAY
R<REJECT> $*            $#error $@ 5.7.1 $: "550 Access denied"
R<DISCARD> $*            $#discard $: discard
R<$+> $*            $#error $@ 5.7.1 $: $1


######################################################################
###  check_mail -- check SMTP `MAIL FROM:' command argument
######################################################################

SLocal_check_mail
Scheck_mail
R$*                  $: $1 $| $>"Local_check_mail" $1
R$* $| $#$*            $#$2
R$* $| $*            $@ $>"Basic_check_mail" $1

SBasic_check_mail
# check for deferred delivery mode
R$*                  $: < ${deliveryMode} > $1
R< d > $*            $@ deferred
R< $* > $*            $: $2

R<>                  $@ <OK>
R$*                  $: <?> $>CanonAddr $1
R<?> $* < @ $+ . >      <?> $1 < @ $2 >                  strip trailing dots
# handle non-DNS hostnames (*.bitnet, *.decnet, *.uucp, etc)
R<?> $* < $* $=P > $*      $: <OK> $1 < @ $2 $3 > $4
R<?> $* < @ $+ > $*      $: <? $(resolve $2 $: $2 <PERM> $) > $1 < @ $2 > $3
R<? $* <$->> $* < @ $+ > $*
                  $: <$2> $3 < @ $4 > $5

# handle case of @localhost on address
R<$+> $* < @localhost >      $: < ? $&{client_name} > <$1> $2 < @localhost >
R<$+> $* < @localhost.$m >
                  $: < ? $&{client_name} > <$1> $2 < @localhost.$m >
R<$+> $* < @localhost.UUCP >
                  $: < ? $&{client_name} > <$1> $2 < @localhost.UUCP >
R<? $=w> <$+> $*      <?> <$2> $3
R<? $+> <$+> $*            $#error $@ 5.5.4 $: "553 Real domain name required"
R<?> <$+> $*            $: <$1> $2

# lookup localpart (user@)
R<$+> $* < @ $+ > $*      $: <USER $(access $2@ $: ? $) > <$1> $2 < @ $3 > $4
# no match, try full address (user@domain rest)
R<USER ?> <$+> $* < @ $* > $*
                  $: <USER $(access $2@$3$4 $: ? $) > <$1> $2 < @ $3 > $4
# no match, try address (user@domain)
R<USER ?> <$+> $+ < @ $+ > $*
                  $: <USER $(access $2@$3 $: ? $) > <$1> $2 < @ $3 > $4
# no match, try (sub)domain (domain)
R<USER ?> <$+> $* < @ $+ > $*
                  $: $>LookUpDomain <$3> <$1> <>
# check unqualified user in access database
R<?> $*                  $: <USER $(access $1@ $: ? $) > <?> $1
# retransform for further use
R<USER $+> <$+> $*      $: <$1> $3

# handle case of no @domain on address
R<?> $*                  $: < ? $&{client_name} > $1
R<?> $*                  $@ <OK>                        ...local unqualed ok
R<? $+> $*            $#error $@ 5.5.4 $: "553 Domain name required"
                                          ...remote is not
# check results
R<?> $*                  $@ <OK>
R<OK> $*            $@ <OK>
R<TEMP> $*            $#error $@ 4.1.8 $: "451 Sender domain must resolve"
R<PERM> $*            $#error $@ 5.1.8 $: "501 Sender domain must exist"
R<RELAY> $*            $@ <RELAY>
R<DISCARD> $*            $#discard $: discard
R<REJECT> $*            $#error $@ 5.7.1 $: "550 Access denied"
R<$+> $*            $#error $@ 5.7.1 $: $1            error from access db

######################################################################
###  check_rcpt -- check SMTP `RCPT TO:' command argument
######################################################################

SLocal_check_rcpt
Scheck_rcpt
R$*                  $: $1 $| $>"Local_check_rcpt" $1
R$* $| $#$*            $#$2
R$* $| $*            $@ $>"Basic_check_rcpt" $1

SBasic_check_rcpt
# check for deferred delivery mode
R$*                  $: < ${deliveryMode} > $1
R< d > $*            $@ deferred
R< $* > $*            $: $2

R$*                  $: $>ParseRecipient $1            strip relayable hosts



# blacklist local users or any host from receiving mail
R$*                  $: <?> $1
R<?> $+ < @ $=w >      $: <> <USER $1> <FULL $1@$2> <HOST $2> <$1 < @ $2 >>
R<?> $+ < @ $* >      $: <> <FULL $1@$2> <HOST $2> <$1 < @ $2 >>
R<?> $+                  $: <> <USER $1> <$1>
R<> <USER $+> $*      $: <$(access $1 $: $)> $2
R<> <FULL $+> $*      $: <$(access $1 $: $)> $2
R<OK> <FULL $+> $*      $: <$(access $1 $: $)> $2
R<> <HOST $+> $*      $: <$(access $1 $: $)> $2
R<OK> <HOST $+> $*      $: <$(access $1 $: $)> $2
R<> <$*>            $: $1
R<OK> <$*>            $: $1
R<RELAY> <$*>            $: $1
R<REJECT> $*            $#error $@ 5.2.1 $: "550 Mailbox disabled for this recipient"
R<$+> $*            $#error $@ 5.2.1 $: $1                  error from access db

# anything terminating locally is ok
R$+ < @ $=w >            $@ OK
R$+ < @ $* $=R >      $@ OK
R$+ < @ $* >            $: $>LookUpDomain <$2> <?> <$1 < @ $2 >>
R<RELAY> $*            $@ RELAY
R<$*> <$*>            $: $2


# check for local user (i.e. unqualified address)
R$*                  $: <?> $1
R<?> $* < @ $+ >      $: <REMOTE> $1 < @ $2 >
# local user is ok
R<?> $+                  $@ OK
R<$+> $*            $: $2

# anything originating locally is ok
R$*                  $: <?> $&{client_name}
# check if bracketed IP address (forward lookup != reverse lookup)
R<?> [$+]            $: <BAD> [$1]
# pass to name server to make hostname canonical
R<?> $* $~P             $: <?> $[ $1 $2 $]
R<$-> $*            $: $2
R$* .                  $1                        strip trailing dots
R$@                  $@ OK
R$=w                  $@ OK
R$* $=R                  $@ OK
R$*                  $: $>LookUpDomain <$1> <?> <$1>
R<RELAY> $*            $@ RELAY
R<$*> <$*>            $: $2

# check IP address
R$*                  $: $&{client_addr}
R$@                  $@ OK                  originated locally
R0                  $@ OK                  originated locally
R$=R $*                  $@ OK                  relayable IP address
R$*                  $: $>LookUpAddress <$1> <?> <$1>
R<RELAY> $*             $@ RELAY            relayable IP address
R<$*> <$*>            $: $2
R$*                  $: [ $1 ]            put brackets around it...
R$=w                  $@ OK                  ... and see if it is local


# anything else is bogus
R$*                  $#error $@ 5.7.1 $: "550 Relaying denied"

#
######################################################################
######################################################################
#####
#####                  MAILER DEFINITIONS
#####
######################################################################
######################################################################


######################*****##############
###   PROCMAIL Mailer specification   ###
##################*****##################

#####  @(#)procmail.m4      8.11 (Berkeley) 5/19/1998  #####

Mprocmail,      P=/usr/bin/procmail, F=DFMSPhnu9, S=11/31, R=21/31, T=DNS/RFC822/X-Unix,
            A=procmail -Y -m $h $f $u

#####################################
###   SMTP Mailer specification   ###
#####################################

#####  @(#)smtp.m4      8.38 (Berkeley) 5/19/1998  #####

Msmtp,            P=[IPC], F=mDFMuX, S=11/31, R=21, E=\r\n, L=990,
            T=DNS/RFC822/SMTP,
            A=IPC $h
Mesmtp,            P=[IPC], F=mDFMuXa, S=11/31, R=21, E=\r\n, L=990,
            T=DNS/RFC822/SMTP,
            A=IPC $h
Msmtp8,            P=[IPC], F=mDFMuX8, S=11/31, R=21, E=\r\n, L=990,
            T=DNS/RFC822/SMTP,
            A=IPC $h
Mrelay,            P=[IPC], F=mDFMuXa8, S=11/31, R=61, E=\r\n, L=2040,
            T=DNS/RFC822/SMTP,
            A=IPC $h

#
#  envelope sender rewriting
#
S11
R$+                  $: $>51 $1                  sender/recipient common
R$* :; <@>            $@                        list:; special case
R$*                  $: $>61 $1                  qualify unqual'ed names
R$+                  $: $>94 $1                  do masquerading


#
#  envelope recipient rewriting --
#  also header recipient if not masquerading recipients
#
S21
R$+                  $: $>51 $1                  sender/recipient common
R$+                  $: $>61 $1                  qualify unqual'ed names


#
#  header sender and masquerading header recipient rewriting
#
S31
R$+                  $: $>51 $1                  sender/recipient common
R:; <@>                  $@                        list:; special case

# do special header rewriting
R$* <@> $*            $@ $1 <@> $2                  pass null host through
R< @ $* > $*            $@ < @ $1 > $2                  pass route-addr through
R$*                  $: $>61 $1                  qualify unqual'ed names
R$+                  $: $>93 $1                  do masquerading


#
#  convert pseudo-domain addresses to real domain addresses
#
S51

# pass <route-addr>s through
R< @ $+ > $*            $@ < @ $1 > $2                  resolve <route-addr>

# output fake domains as user%fake@relay

# do UUCP heuristics; note that these are shared with UUCP mailers
R$+ < @ $+ .UUCP. >      $: < $2 ! > $1                  convert to UUCP form
R$+ < @ $* > $*            $@ $1 < @ $2 > $3            not UUCP form

# leave these in .UUCP form to avoid further tampering
R< $&h ! > $- ! $+      $@ $2 < @ $1 .UUCP. >
R< $&h ! > $-.$+ ! $+      $@ $3 < @ $1.$2 >
R< $&h ! > $+            $@ $1 < @ $&h .UUCP. >
R< $+ ! > $+            $: $1 ! $2 < @ $Y >            use UUCP_RELAY
R$+ < @ $+ : $+ >      $@ $1 < @ $3 >                  strip mailer: part
R$+ < @ >            $: $1 < @ *LOCAL* >            if no UUCP_RELAY


#
#  common sender and masquerading recipient rewriting
#
S61

R$* < @ $* > $*            $@ $1 < @ $2 > $3            already fully qualified
R$+                  $@ $1 < @ *LOCAL* >            add local qualification


#
#  relay mailer header masquerading recipient rewriting
#
S71

R$+                  $: $>61 $1
R$+                  $: $>93 $1


##################################################
###   Local and Program Mailer specification   ###
##################################################

#####  @(#)local.m4      8.30 (Berkeley) 6/30/1998  #####

Mlocal,            P=/usr/bin/procmail, F=lsDFMAw5:/|@qSPfhn9, S=10/30, R=20/40,
            T=DNS/RFC822/X-Unix,
            A=procmail -Y -a $h -d $u
Mprog,            P=/usr/sbin/smrsh, F=lsDFMoqeu9, S=10/30, R=20/40, D=$z:/,
            T=X-Unix,
            A=sh -c $u

#
#  Envelope sender rewriting
#
S10
R<@>                  $n                  errors to mailer-daemon
R@ <@ $*>            $n                  temporarily bypass Sun bogosity
R$+                  $: $>50 $1            add local domain if needed
R$*                  $: $>94 $1            do masquerading

#
#  Envelope recipient rewriting
#
S20
R$+ < @ $* >            $: $1                  strip host part

#
#  Header sender rewriting
#
S30
R<@>                  $n                  errors to mailer-daemon
R@ <@ $*>            $n                  temporarily bypass Sun bogosity
R$+                  $: $>50 $1            add local domain if needed
R$*                  $: $>93 $1            do masquerading

#
#  Header recipient rewriting
#
S40
R$+                  $: $>50 $1            add local domain if needed

#
#  Common code to add local domain name (only if always-add-domain)
#
S50
R$* < @ $* > $*       $@ $1 < @ $2 > $3            already fully qualified
R$+                  $@ $1 < @ *LOCAL* >            add local qualification
0
Comment
Question by:pucko
[X]
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9 Comments
 
LVL 51

Expert Comment

by:ahoffmann
ID: 2060007
O PrivacyOptions=goaway,needmailhelo
0
 
LVL 1

Author Comment

by:pucko
ID: 2060206
OK!

I added this:
###############
#   Options   #
###############



O PrivacyOptions=goaway,needmailhelo

And I still get:

                Sendmail supports the EHLO greetings
                which means that it supports the ESMTP, which may be the source of additional security flaws that can be used by attackers.
                Solutions: dissable this feture in sendmail.conf

The remote sendmail allows mail relaying. Spamers can send mail using this host.


So the only thing that htat fix is the EXPN thing
0
 
LVL 51

Expert Comment

by:ahoffmann
ID: 2062070
FR-o /etc/mail/relay_domains
# in this file write all domains that are allowed to use your host for relaying
# I'm not shure if this will prevent your check program for complaining about EHELO
# please read the docs which come with sendmail 8.9.x for details
0
Efficient way to get backups off site to Azure

This user guide provides instructions on how to deploy and configure both a StoneFly Scale Out NAS Enterprise Cloud Drive virtual machine and Veeam Cloud Connect in the Microsoft Azure Cloud.

 

Expert Comment

by:mrc197
ID: 2066177
If I were you I wouldn't worry to much about the (small) possiblity of attackers using esmtp to attack your site. There are probably other security holes in your system that are considerably more vunerable.
Just how secure does this machine really need to be? It's impossible to make any machine completely secure while still being usable.
0
 

Expert Comment

by:msecaur
ID: 2066491
Well, for the relaying issues, you can edit the /etc/mail/relay-domains file and include a list of hosts that are allowed to use this host as a relay host.  You can use partial domain names for wildcards.  For example, to include host1.foo.com, host2.foo.com, and host3.foo.com, you needn't put all machines in the file, you can simply put in

foo.com

and it will work.  IP addresses also work. To allow anything from 130.12.4.*, just put in

130.12.4

The host should not allow any host that does not meet these criterion to relay using this host.

http://www.harker.com has a bunch of helpful stuff.
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Author Comment

by:pucko
ID: 2066552
What about this then?

                      Sendmail supports the EHLO greetings
                      which means that it supports the ESMTP, which may be the source of additional security flaws that can be used by
      attackers.
                      Solutions: dissable this feture in sendmail.conf
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Expert Comment

by:ahoffmann
ID: 2067500
Forget it.
Your MTA anounces itself with the hint that it supports ESMTP, you may try to tweak this banner message with

confSMTP_LOGIN_MSG

just to fake your checker program.

AFAIK, the only way to disable ESMTP (using SMTP instead), is to recompile sendmail (after patching sendmail.h, see *ESMTP defines).
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Author Comment

by:pucko
ID: 2067689
Ah ok... can you ahoffman tell me what
O PrivacyOptions=goaway,needmailhelo
are doing? Then mark the question as answerd.
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Accepted Solution

by:
ahoffmann earned 300 total points
ID: 2068480
> needmailhelo
insist on HELO or EHLO command before MAIL
> goaway
Disallow essentially all SMTP status queries
goaway = (no VRFY, no ETRN, no VERB, no EXPN

BTW, the m4 "confSMTP_LOGIN_MSG" expands to
O SmtpGreetingMessage=....
in your sendmail.cf
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