Summary: Question: /etc/issue

From: shubin@peabody.jhu.edu
Date: Fri Apr 09 1999 - 12:21:46 CDT


Hi, Managers;

This a great list. I appreciate your help:

Richard Lacroix <Richard.Lacroix@sisca.com>
Claude Charest <charest@chou.CANR.Hydro.Qc.Ca>
Michael J. Connolly <mjconnly@newton41.ckcorp.com>
Timothy P. Peterman <timothy.p.peterman@lmco.com>
Ali q8@sunuio.comwarehq.com.ec
Mark Hargrave <hargrme@wisdom.maf.nasa.gov>
Franczyk, Gary <gfranczyk@carbomedics.com>
Peter Laws <plaws@enterprise.nssl.noaa.gov>
Michael Kriss <kriss@fnal.gov>
Larry Chin <larry@sprint.ca>
Jim McVey <jmcvey@nhgri.nih.gov>
Gustavo A. Lozano <glozano@Colinter.net>
Douglas Palmer <palmer@nyed.uscourts.gov>
Sergey Mokryshev <mokr@child.ru>
Roger Fujii <rmf@lookhere.com>
Dan Anderson <dana@dtn.com>
Dennis Martens <MARTENSD@health.qld.gov.au>
Carlo Musante <carlo@hub.eng.wayne.edu>
Chris Wheeler <chris.wheeler@wcom.com>
Chad Price <cprice@molbio.unmc.edu>
Karl Baker <Karl.Baker@matrox.com>
Sean Quaint <squaint@provide.net>
Nikos George <nikos@jimmy.harvard.edu>
Luc Lauwers <luc.lauwers@eds.com>
Justin.Stringfellow@barclays.co.uk
Wolf Schaefer <schaefer@wolfe.llnl.gov>
Jeff Waldron <jeffdw123@hotmail.com>

And following are the very helpful/interesteing replys:

-----------------------------------------------------------------
From: jerry lu <oxygen@helix.nih.gov>

Hi,
If you run "man in.telnetd" you'll see the answer:
==================================================================
     The banner printed by in.telnetd is configurable. The
     default is (more or less) equivalent to "`uname -sr`" and
     will be used if no banner is set in /etc/default/telnetd.
     To set the banner, add a line of the form

         BANNER="..."
     to /etc/default/telnetd. Nonempty banner strings are fed to
     shells for evaluation. The default banner may be obtained
     by

         BANNER="\\r\\n\\r\\n`uname -s` `uname -r`\\r\\n\\r\\n"

     and no banner will be printed if /etc/default/telnetd con-
     tains

         BANNER=""
==================================================================

The same rule applies to in.ftpd (file /etc/default/ftpd). Run "man
in.ftpd" for details.

FYI, disabling the banner would probably give you a little help on
securing your machine, but not too much! There are lots of hacking tools
available on the Internet which can tell the OS of your machine by
analysing the responsive packets. Check out the Phrack magazine, volume
8, issue 54, article 9: "Remote OS detection via TCP/IP Stack
Fingerprinting" for more information.

Jerry

------------------------------------------------------------------

From: Sergey Mokryshev <mokr@child.ru>

/etc/default/telnetd
BANNER="\n\n Amstrad 128K Microcomputer (v3)\n (C) 1985 Amstrad Consumer
\
Electronics plc\n and Locomotive Software Ltd.\n BASIC
1.1\n\n"

Sincerely,
==============================
Sergey Mokryshev <mokr@child.ru>
Moscow Children Computer Club
Network Administrator
http://www.child.ru/
==============================

----------------------------------------
From: Luc Lauwers <luc.lauwers@eds.com>

Subin,

the 'SunOS 5.6' message is the default message printed by the telnet
daemon.
>From Solaris 2.6 on this message is customizible.
Create a file 'telnetd' in /etc/default, and put in a line with:
BANNER="Your message here".
If you make that BANNER ="", you won't get any extra info from telnetd.
See man telnetd (1M) for all the details.

Hope this helps,
Luc.
----------------------------------------

From: dana@dtn.com

Here is some basic Solaris Security stuff I generally do. The answer you
are looking for is in #2 and #6.

Dan Anderson

1. Action: Disable direct root logins (telnet)
   Procedure: Uncomment the line in /etc/default/login that reads
   #CONSOLE=/dev/console
   Results: It now requires 2 logins to have root access (telnet), a
valid
   user, and the root password

2. Action: Modify the telnet greeting from disclosing the operating
system
   Procedure: Create a file named /etc/default/telnetd. In this file
place the
   line BANNER=?_______________\\r\\n? (Where _____ is whatever message
you
   want)
   Results: Not knowing what OS a server is running makes breaking into
it MUCH
   more difficult.

3. Action: Disable root ftp login
   Procedure: Create/edit the file named /etc/ftpusers. Ensure the root
user
   is listed. Also consider other
   Users who do not REQUIRE ftp access.
Results: It now requires 2 logins to have root access (FTP), a valid user,
   and the root password

4. Action: Set umask for FTP
   Procedure: Edit /etc/default/ftpd and make the umask the most
restrictive
   that you can. Consider 027 or 077.
   Results: New files transferred in are more secure, reduces incidents
of
   Trojan Horses, and Viruses.

5. Action: Set system umask
   Procedure: Edit the /etc/profile and make the umask the most
restrictive
   that you can. Consider 027 or 077.
   Result: New files created are more secure, the user must explicitly
give away
   rights for their files.

6. Action: Modify the FTP greeting from disclosing the operating system
   Procedure: Create a file named /etc/default/ftpd. In this file place
the
   line BANNER=?_______________\\r\\n? (Where _____ is whatever message
you
   want)
   Results: Not knowing what OS a server is running makes breaking into
it MUCH
   more difficult.

7. Action: Make sure you are not running anonymous ftp (unless you want
it)
   Procedure: Make sure that there is NOT a user named ftp listed in the
   /etc/passwd.
   Result: Disables anonymous ftp

8. Action: Ensure all unused services are disabled.
   Procedure: Edit the /etc/inetd.conf and comment out the lines for
services
   you do not NEED.
   Result: With each removed service you have removed a potential
security
   hole.

9. Action: Disable processes that are not needed
   Procedure: Look through the /etc/rc2.d and /etc/rc3.d directories for
files
   with the name S______. These files are scripts that are executed when
init
   changes run levels (2 is multiuser and 3 is multiuser with exported
file
   systems). Any/all of these can be shut off by renaming them to ?_____
(where
   ? is any character but S or K (S ? Start K ? Kill).
? is any character but S or K (S ? Start K ? Kill).
   Results: Less processes not only increases performance, but also
reduces the
   security risks (i.e. sendmail)

10. Action: Verify that you are ONLY exporting the file systems you NEED
to,
and then only with VERY restricted rights.
   Procedure: Edit the /etc/dfstab
   Results: Enhances security by ensuring unauthorized personnel do not
have
   access to data.

11. Action: Change the default message of the day (motd) so it does not
disclose the OS.
   Procedure: Edit/remove the /etc/motd file.
   Results: Not knowing what OS a server is running makes breaking into
it MUCH
   more difficult.

12. Action: Extend the minimum password length to 8 characters
   Procedure: Modify the /etc/default/passwd so that the pass length = 8
   Results: Eight characters is now recommended by government security
experts.
   Longer passwords = more capability to be secure passwords

13. Action: If acceptable set up password aging (Most useful for
interactive
users (i.e. not automated processes).
   Procedure: Modify the MINWEEKS and MAXWEEKS parameters in
   /etc/default/passwd file
   Results: By forcing users to periodically change their passwords
compromised
   passwords will expire

14. Action: Keep OS current and document Patch/fix versions
   Procedure: Routinely download and install recommended patch clusters
from
   sunsolve.sun.com
   Result: Bug fixes/Security fixes are distributed via this means. If
well
   documented then you will be able to quickly ascertain if a security
advisory
   affects you.

15. Action: Ensure logging is setup to log su?s and the information is
stored
on at least 1 other machine.
   Procedure: Edit the /etc/default/su file to ensure that the SULOG is
set to
   /var/adm/sulog and the SYSLOG is set to YES. Then edit the
/etc/syslog.conf
to send a copy of ALL messages to another host.
   Result: It is critical to know who is su?ing. When logged
appropriately it
   is a good indicator for security. It is also important to have another
copy
   of the log files so that it is more difficult to hide a break in.

16. Action: Disable X connections to the server.
   Procedure: Add xhost ? to the CDE startup file
(/usr/dt/config/sys.dtprofile
   or better /etc/dt/config/.dtprofile
   Result: Unauthorized users will not be able to display to your X
server.

17. Action: Consider restricted/no shell for users
   Procedure: If a user does not require a full featured shell account
then
   give them a shell (In /etc/passwd) of either /bin/rksh for a severly
limited
   shell or /bin/false for no shell. Do this for system accounts as well
if
   possible.
   Result: Less users will have expanded access to your systems.

18. Action: Strongly consider installing a TCP/IP wrapper such as
TCPWrap or
IPFilter
   Procedure: Varies by system selected
   Results: TCP/IP access is logged and/or blocked as necessary.

19. Action: Disable all ?Trusts? setup
   Procedure: Write a script that finds all hosts.equiv and .rhosts
files,
   notes their location and removes them. Run this script daily from
cron, and
   examine what it finds.
   Result: The system will not automatically trust other systems. Your
users
   will not be able to easily decrease your security.



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