source: trunk/third/sendmail/README @ 19204

                        SENDMAIL RELEASE 8

This directory has the latest sendmail(TM) software from Sendmail, Inc.

Report any bugs to sendmail-bugs@sendmail.ORG

There is a web site at http://WWW.Sendmail.ORG/ -- see that site for
the latest updates.

+--------------+
| INTRODUCTION |
+--------------+

0. The vast majority of queries to <sendmail-questions@sendmail.org>
   are answered in the README files noted below.

1. Read this README file, especially this introduction, and the DIRECTORY
   PERMISSIONS sections.

2. Read the INSTALL file in this directory.

3. Read sendmail/README, especially:
   a. the introduction
   b. the BUILDING SENDMAIL section
   c. the relevant part(s) of the OPERATING SYSTEM AND COMPILE QUIRKS section

   You may also find these useful:

   d. sendmail/SECURITY
   e. devtools/README
   f. devtools/Site/README
   g. libmilter/README
   h. mail.local/README
   i. smrsh/README

4. Read cf/README.

Sendmail is a trademark of Sendmail, Inc.

+-----------------------+
| DIRECTORY PERMISSIONS |
+-----------------------+

Sendmail often gets blamed for many problems that are actually the
result of other problems, such as overly permissive modes on directories.
For this reason, sendmail checks the modes on system directories and
files to determine if they can be trusted.  For sendmail to run without
complaining, you MUST execute the following command:

        chmod go-w / /etc /etc/mail /usr /var /var/spool /var/spool/mqueue
        chown root / /etc /etc/mail /usr /var /var/spool /var/spool/mqueue

You will probably have to tweak this for your environment (for example,
some systems put the spool directory into /usr/spool instead of
/var/spool).  If you set the RunAsUser option in your sendmail.cf, the
/var/spool/mqueue directory will have to be owned by the RunAsUser user.
As a general rule, after you have compiled sendmail, run the command

        sendmail -v -bi

to initialize the alias database.  If it gives messages such as

        WARNING: writable directory /etc
        WARNING: writable directory /var/spool/mqueue

then the directories listed have inappropriate write permissions and
should be secured to avoid various possible security attacks.

Beginning with sendmail 8.9, these checks have become more strict to
prevent users from being able to access files they would normally not
be able to read.  In particular, .forward and :include: files in unsafe
directory paths (directory paths which are group or world writable) will
no longer be allowed.  This would mean that if user joe's home directory
was writable by group staff, sendmail would not use his .forward file.
This behavior can be altered, at the expense of system security, by
setting the DontBlameSendmail option.  For example, to allow .forward
files in group writable directories:

        O DontBlameSendmail=forwardfileingroupwritabledirpath

Or to allow them in both group and world writable directories:

        O DontBlameSendmail=forwardfileinunsafedirpath

Items from these unsafe .forward and :include: files will be marked
as unsafe addresses -- the items can not be deliveries to files or
programs.  This behavior can also be altered via DontBlameSendmail:

        O DontBlameSendmail=forwardfileinunsafedirpath,
                forwardfileinunsafedirpathsafe

The first flag allows the .forward file to be read, the second allows
the items in the file to be marked as safe for file and program
delivery.

Other files affected by this strengthened security include class
files (i.e., Fw /etc/mail/local-host-names), persistent host status files,
and the files specified by the ErrorHeader and HelpFile options.  Similar
DontBlameSendmail flags are available for the class, ErrorHeader, and
HelpFile files.

If you have an unsafe configuration of .forward and :include:
files, you can make it safe by finding all such files, and doing
a "chmod go-w $FILE" on each.  Also, do a "chmod go-w $DIR" for
each directory in the file's path.


+--------------------------+
| FILE AND MAP PERMISSIONS |
+--------------------------+

Any application which uses either flock() or fcntl() style locking or
other APIs that use one of these locking methods (such as open() with
O_EXLOCK and O_SHLOCK) on files readable by other local untrusted users
may be susceptible to local denial of service attacks.

File locking is used throughout sendmail for a variety of files
including aliases, maps, statistics, and the pid file.  Any user who
can open one of these files can prevent sendmail or it's associated
utilities, e.g., makemap or newaliases, from operating properly.  This
can also affect sendmail's ability to update status files such as
statistics files.  For system which use flock() for file locking, a
user's ability to obtain an exclusive lock prevents other sendmail
processes from reading certain files such as alias or map databases.

A workaround for this problem is to protect all sendmail files such
that they can't be opened by untrusted users.  As long as users can
not open a file, they can not lock it.  Since queue files should
already have restricted permissions, the only files that need
adjustment are alias, map, statistics, and pid files.  These files
should be owned by root or the trusted user specified in the
TrustedUser option.  Changing the permissions to be only readable and
writable by that user is sufficient to avoid the denial of service.
For example, depending on the paths you use, these commands would be
used:

        chmod 0640 /etc/mail/aliases /etc/mail/aliases.{db,pag,dir}
        chmod 0640 /etc/mail/*.{db,pag,dir}
        chmod 0640 /etc/mail/statistics /var/log/sendmail.st
        chmod 0600 /var/run/sendmail.pid /etc/mail/sendmail.pid

If the permissions 0640 are used, be sure that only trusted users belong
to the group assigned to those files.  Otherwise, files should not even
be group readable.  As of sendmail 8.12.4, the permissions shown above
are the default permissions for newly created files.

Note that the denial of service on the plain text aliases file
(/etc/mail/aliases) only prevents newaliases from rebuilding the
aliases file.  The same is true for the database files on systems which
use fcntl() style locking.  Since it does not interfere with normal
operations, sites may chose to leave these files readable.  Also, it is
not necessary to protect the text files associated with map databases
as makemap does not lock those files.


+-----------------------+
| RELATED DOCUMENTATION |
+-----------------------+

There are other files you should read.  Rooted in this directory are:

  FAQ
        The FAQ (frequently answered questions) is no longer maintained
        with the sendmail release.  It is available at
        http://www.sendmail.org/faq/ .  The file FAQ is a reminder of
        this and a pointer to the web page.
  INSTALL
        Installation instructions for building and installing sendmail.
  KNOWNBUGS
        Known bugs in the current release.
  RELEASE_NOTES
        A detailed description of the changes in each version.  This
        is quite long, but informative.
  sendmail/README
        Details on compiling and installing sendmail.
  cf/README
        Details on configuring sendmail.
  doc/op/op.me
        The sendmail Installation & Operations Guide.  In addition
        to the shipped PostScript version, plain text and PDF versions
        can be generating using (assuming the required conversion software
        is installed on your system, see doc/op/Makefile):

        cd doc/op && make op.txt op.pdf

        Be warned: on some systems calling make in doc/op/ will cause
        errors due to nroff/groff problems.  Known problems are:
        - running this off on systems with an old version of -me, you
        need to add the following macro to the macros:

                .de sm
                \s-1\\$1\\s0\\$2
                ..

        This sets a word in a smaller pointsize.

        - with new groff versions (1.18 seems affected)

        GROFF_NO_SGR=1

        needs to be set, e.g., in doc/op/Makefile:

        ROFF_CMD=       GROFF_NO_SGR=1 groff


+--------------+
| RELATED RFCS |
+--------------+

There are several related RFCs that you may wish to read -- they are
available via anonymous FTP to several sites.  For a list of the
primary repositories see:

        http://www.isi.edu/in-notes/rfc-retrieval.txt

They are also online at:

        http://www.ietf.org/

They can also be retrieved via electronic mail by sending
email to one of:

        mail-server@nisc.sri.com
                Put "send rfcNNN" in message body
        nis-info@nis.nsf.net
                Put "send RFCnnn.TXT-1" in message body
        sendrfc@jvnc.net
                Put "RFCnnn" as Subject: line

For further instructions see:

        http://www.isi.edu/in-notes/rfc-editor/rfc-info

Important RFCs for electronic mail are:

        RFC821  SMTP protocol
        RFC822  Mail header format
        RFC974  MX routing
        RFC976  UUCP mail format
        RFC1123 Host requirements (modifies 821, 822, and 974)
        RFC1344 Implications of MIME for Internet Mail Gateways
        RFC1413 Identification server
        RFC1428 Transition of Internet Mail from Just-Send-8 to
                8-bit SMTP/MIME
        RFC1652 SMTP Service Extension for 8bit-MIMEtransport
        RFC1869 SMTP Service Extensions (ESMTP spec)
        RFC1870 SMTP Service Extension for Message Size Declaration
        RFC1891 SMTP Service Extension for Delivery Status Notifications
        RFC1892 Multipart/Report Content Type for the Reporting of
                Mail System Administrative Messages
        RFC1893 Enhanced Mail System Status Codes
        RFC1894 An Extensible Message Format for Delivery Status
                Notifications
        RFC1985 SMTP Service Extension for Remote Message Queue Starting
        RFC2033 Local Mail Transfer Protocol (LMTP)
        RFC2034 SMTP Service Extension for Returning Enhanced Error Codes
        RFC2045 Multipurpose Internet Mail Extensions (MIME) Part One:
                Format of Internet Message Bodies
        RFC2476 Message Submission
        RFC2487 SMTP Service Extension for Secure SMTP over TLS
        RFC2554 SMTP Service Extension for Authentication
        RFC2821 Simple Mail Transfer Protocol
        RFC2822 Internet Message Format
        RFC2852 Deliver By SMTP Service Extension
        RFC2920 SMTP Service Extension for Command Pipelining

Other standards that may be of interest (but which are less directly
relevant to sendmail) are:

        RFC987  Mapping between RFC822 and X.400
        RFC1049 Content-Type header field (extension to RFC822)

Warning to AIX users: this version of sendmail does not implement
MB, MR, or MG DNS resource records, as defined (as experiments) in
RFC1035.


+---------+
| WARNING |
+---------+

Since sendmail 8.11 and later includes hooks to cryptography, the
following information from OpenSSL applies to sendmail as well.

PLEASE REMEMBER THAT EXPORT/IMPORT AND/OR USE OF STRONG CRYPTOGRAPHY
SOFTWARE, PROVIDING CRYPTOGRAPHY HOOKS OR EVEN JUST COMMUNICATING
TECHNICAL DETAILS ABOUT CRYPTOGRAPHY SOFTWARE IS ILLEGAL IN SOME
PARTS OF THE WORLD.  SO, WHEN YOU IMPORT THIS PACKAGE TO YOUR
COUNTRY, RE-DISTRIBUTE IT FROM THERE OR EVEN JUST EMAIL TECHNICAL
SUGGESTIONS OR EVEN SOURCE PATCHES TO THE AUTHOR OR OTHER PEOPLE
YOU ARE STRONGLY ADVISED TO PAY CLOSE ATTENTION TO ANY EXPORT/IMPORT
AND/OR USE LAWS WHICH APPLY TO YOU.  THE AUTHORS ARE NOT LIABLE FOR
ANY VIOLATIONS YOU MAKE HERE.  SO BE CAREFUL, IT IS YOUR RESPONSIBILITY.

If you use OpenSSL then make sure you read their README file which
contains information about patents etc.


+-------------------+
| DATABASE ROUTINES |
+-------------------+

IF YOU WANT TO RUN THE NEW BERKELEY DB SOFTWARE:  ****  DO NOT  ****
use the version that was on the Net2 tape -- it has a number of
nefarious bugs that were bad enough when I got them; you shouldn't have
to go through the same thing.  Instead, get a new version via the web at
http://www.sleepycat.com/.  This software is highly recommended; it gets
rid of several stupid limits, it's much faster, and the interface is
nicer to animals and plants.  If the Berkeley DB include files
are installed in a location other than those which your compiler searches,
you will need to provide that directory when building:

        Build -I/path/to/include/directory

If you are using Berkeley DB versions 1.85 or 1.86, you are *strongly*
urged to upgrade to DB version 2 or later, available from
http://www.sleepycat.com/.  Berkeley DB versions 1.85 and 1.86 are known to
be broken in various nasty ways (see http://www.sleepycat.com/db.185.html),
and can cause sendmail to dump core.  In addition, the newest versions of
gcc and the Solaris compilers perform optimizations in those versions that
may cause fairly random core dumps.

If you have no choice but to use Berkeley DB 1.85 or 1.86, and you are
using both Berkeley DB and files in the UNIX ndbm format, remove ndbm.h
and ndbm.o from the DB library after building it.  You should also apply
all of the patches for DB 1.85 and 1.86 found at the Sleepycat web site
(see http://www.sleepycat.com/db.185.html), as they fix some of the known
problems.

If you are using a version of Berkeley DB 2 previous to 2.3.15, and you
are using both Berkeley DB and files in the UNIX ndbm format, remove dbm.o
from the DB library after building it.  No other changes are necessary.

If you are using Berkeley DB version 2.3.15 or greater, no changes are
necessary.

The underlying database file formats changed between Berkeley DB versions
1.85 and 1.86, again between DB 1.86 and version 2.0, and finally between
DB 2.X and 3.X.  If you are upgrading from one of those versions, you must
recreate your database file(s).  Do this by rebuilding all maps with
makemap and rebuilding the alias file with newaliases.


+--------------------+
| HOST NAME SERVICES |
+--------------------+

If you are using NIS or /etc/hosts, it is critical that you
list the long (fully qualified) name somewhere (preferably first) in
the /etc/hosts file used to build the NIS database.  For example, the
line should read

        128.32.149.68   mastodon.CS.Berkeley.EDU mastodon

**** NOT ****

        128.32.149.68   mastodon

If you do not include the long name, sendmail will complain loudly
about ``unable to qualify my own domain name (mastodon) -- using
short name'' and conclude that your canonical name is the short
version and use that in messages.  The name "mastodon" doesn't mean
much outside of Berkeley, and so this creates incorrect and unreplyable
messages.


+-------------+
| USE WITH MH |
+-------------+

This version of sendmail notices and reports certain kinds of SMTP
protocol violations that were ignored by older versions.  If you
are running MH you may wish to install the patch in contrib/mh.patch
that will prevent these warning reports.  This patch also works
with the old version of sendmail, so it's safe to go ahead and
install it.


+----------------+
| USE WITH IDENT |
+----------------+

Sendmail 8 supports the IDENT protocol, as defined by RFC 1413.
Note that the RFC states a client should wait at least 30 seconds
for a response.  As of 8.10.0, the default Timeout.ident is 5 seconds
as many sites have adopted the practice of dropping IDENT queries.
This has lead to delays processing mail.

No ident server is included with this distribution.  It is available
from:

  ftp://ftp.lysator.liu.se/pub/ident/servers/
  http://sf.www.lysator.liu.se/~pen/pidentd/

+-------------------------+
| INTEROPERATION PROBLEMS |
+-------------------------+

Microsoft Exchange Server 5.0
        We have had a report that ``about 7% of messages from Sendmail
        to Exchange were not being delivered with status messages of
        "connection reset" and "I/O error".''  Upgrading Exchange from
        Version 5.0 to Version 5.5 Service Pack 2 solved this problem.

CommuniGate Pro
        CommuniGate Pro 3.2.4 does not accept the AUTH= -parameter on
        the MAIL FROM command if the client is not authenticated.  Use

                define(`confAUTH_OPTIONS', `A')

        in .mc file if you have compiled sendmail with Cyrus SASL
        and you communicate with CommuniGate Pro servers.

+---------------------+
| DIRECTORY STRUCTURE |
+---------------------+

The structure of this directory tree is:

cf              Source for sendmail configuration files.  These are
                different than what you've seen before.  They are a
                fairly dramatic rewrite, requiring the new sendmail
                (since they use new features).
contrib         Some contributed tools to help with sendmail.  THESE
                ARE NOT SUPPORTED by sendmail -- contact the original
                authors if you have problems.  (This directory is not
                on the 4.4BSD tape.)
devtools        Build environment.  See devtools/README.
doc             Documentation.  If you are getting source, read
                op.me -- it's long, but worth it.
editmap         A program to edit and query maps that have been created
                with makemap, e.g., adding and deleting entries.
include         Include files used by multiple programs in the distribution.
libsmdb         sendmail database library with support for Berkeley DB 1.X,
                Berkeley DB 2.X, Berkeley DB 3.X, and NDBM.
libsmutil       sendmail utility library with functions used by different
                programs.
mail.local      The source for the local delivery agent used for 4.4BSD.
                THIS IS NOT PART OF SENDMAIL! and may not compile
                everywhere, since it depends on some 4.4-isms.  Warning:
                it does mailbox locking differently than other systems.
mailstats       Statistics printing program.
makemap         A program that creates the keyed maps used by the $( ... $)
                construct in sendmail.  It is primitive but effective.
                It takes a very simple input format, so you will probably
                expect to preprocess must human-convenient formats
                using sed scripts before this program will like them.
                But it should be functionally complete.
praliases       A program to print the DBM or NEWDB version of the
                aliases file.
rmail           Source for rmail(8).  This is used as a delivery
                agent for for UUCP, and could presumably be used by
                other non-socket oriented mailers.  Older versions of
                rmail are probably deficient.  RMAIL IS NOT PART OF
                SENDMAIL!!!  The 4.4BSD source is included for you to
                look at or try to port to your system.  There is no
                guarantee it will even compile on your operating system.
smrsh           The "sendmail restricted shell", which can be used as
                a replacement for /bin/sh in the prog mailer to provide
                increased security control.  NOT PART OF SENDMAIL!
sendmail        Source for the sendmail program itself.
test            Some test scripts (currently only for compilation aids).
vacation        Source for the vacation program.  NOT PART OF SENDMAIL!

$Revision: 1.1.1.2 $, Last updated $Date: 2003-04-08 15:08:25 $