LinuxQuestions.org
Share your knowledge at the LQ Wiki.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Security
User Name
Password
Linux - Security This forum is for all security related questions.
Questions, tips, system compromises, firewalls, etc. are all included here.

Notices


Reply
  Search this Thread
Old 02-11-2005, 11:16 AM   #1
Aaclof
LQ Newbie
 
Registered: Feb 2005
Posts: 2

Rep: Reputation: 0
RHEL 3 Security


Hi all,

I have some questions for you about RHEL 3.0 security. I have already found many documents about general UNIX security, but some points are still obscure.

Please take time to try to help me, I would be very grateful. Don't hesitate to explain things even if they seem obvious to you, my knowledge in UNIX's world being very limited...


1) How can we close any connection after a certain period of inactivity ?

2) How can I limit the amount of information given to the user when he is establishing a connection to a server ? (typically not giving the version of OS, etc.)

3) How to make a password respect a predefined policy ? (complexity, aging). I have seen the PAM cracklib module, but is it possible to do the same things without PAM ?

6) General question : if you had to make a RHEL 3 system very secure, which services would you allow and which ones would you make unavailable ?


Thank you for your help. Please answer even if you only know the answer to one question. It will help. And forgive me for my english (I am french).

Bye,

Aaclof
 
Old 02-11-2005, 01:13 PM   #2
peacebwitchu
Member
 
Registered: Apr 2004
Distribution: Debian
Posts: 185

Rep: Reputation: 30
All of you r questions have many different answers depending on configuration and how the server is going to be used.

1). Most all of your firewall devices are going to timeout connections after an idle timeout of roughly 30 minutes. The default idle timeout on RHEL is 2hrs so the firewall times out way before linux gets involved. Here is some info from the kernel source tree.

tcp_keepalive_time - INTEGER
How often TCP sends out keepalive messages when keepalive is enabled.
Default: 2hours.

tcp_keepalive_probes - INTEGER
How many keepalive probes TCP sends out, until it decides that the
connection is broken. Default value: 9.

tcp_keepalive_intvl - INTEGER
How frequently the probes are send out. Multiplied by
tcp_keepalive_probes it is time to kill not responding connection,
after probes started. Default value: 75sec i.e. connection
will be aborted after ~11 minutes of retries.


2) How can I limit the amount of information given to the user when he is establishing a connection to a server ? (typically not giving the version of OS, etc.)

This is usually configurable within the daemon that they are connecting to.

3) How to make a password respect a predefined policy ? (complexity, aging). I have seen the PAM cracklib module, but is it possible to do the same things without PAM ?

Have a look at /etc/login.defs

6) maybe should be 4? General question : if you had to make a RHEL 3 system very secure, which services would you allow and which ones would you make unavailable ?

Only the services you need to accomplish the task the server was setup to do ie if you are running a webserver then you shouldn't have bind (dns server) running as well. Also only install the minimum package set that you need. netstat -anp should only have the services that you need listening for connections.

Last edited by peacebwitchu; 02-11-2005 at 01:15 PM.
 
Old 02-16-2005, 11:47 PM   #3
mastahnke
Member
 
Registered: Feb 2002
Location: IL
Distribution: Ubuntu currently, also Fedora, RHEL, CentOS
Posts: 111

Rep: Reputation: 15
I am not sure why you would want to have users authenticate without using PAM. PAM is a great system for Linux. Care to elaborate?
 
Old 02-17-2005, 02:16 AM   #4
Aaclof
LQ Newbie
 
Registered: Feb 2005
Posts: 2

Original Poster
Rep: Reputation: 0
Well, it is not that I don't want to use PAM. I just wanted to know whether it was possible to authenticate users without it or not.

If you tell me the answer is no, it's fine !!
 
Old 02-17-2005, 08:13 AM   #5
mastahnke
Member
 
Registered: Feb 2002
Location: IL
Distribution: Ubuntu currently, also Fedora, RHEL, CentOS
Posts: 111

Rep: Reputation: 15
I am quite sure you can, though I don't think I would want to. With PAM, you can setup different authentication types and complexities including secure ID, LDAP, and such. I was just curious if you had some motivation not to use PAM.
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Upgrade RHEL 3 AS to RHEL 4 AS louisb Linux - Enterprise 8 06-04-2009 02:57 PM
help needed in security ,vonarabilities ,loopholes in linux security haseebnazar Linux - Security 2 11-23-2005 07:16 PM
[Security Questions] Last Login, how good is this feature for security breach info? t3gah Linux - Security 2 06-14-2005 01:02 AM
todays requirements regarding security (not limited to linux security) markus1982 Linux - Security 8 04-25-2004 10:58 PM
Linux security Vs Windows security keene General 50 11-01-2003 11:22 PM

LinuxQuestions.org > Forums > Linux Forums > Linux - Security

All times are GMT -5. The time now is 09:42 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration