LinuxQuestions.org
Go Job Hunting at the LQ Job Marketplace
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 11-02-2002, 11:45 AM   #1
NSKL
Senior Member
 
Registered: Jan 2002
Location: Rome, Italy ; Novi Sad, Srbija; Brisbane, Australia
Distribution: Ubuntu / ITOS2008
Posts: 1,207

Rep: Reputation: 46
Security in general


A Properly configured Linux system should be fairly secure, but i still have some newbie questions.
If i have all my ports closed (as reported by Nmap) , can someone still connect to my box?
If i have a nfsd or ftpd running, and denied connect to everyone (ALL:ALL) in hosts.deny and granted permission only to computers on my local network (FTPD: IPADRESS-OF-LOCAL-BOXES) in hosts.allow
is this safe?
I also have IPTables setup for NAT, conection sharing between two boxes.
Thanks in advance!
 
Old 11-02-2002, 01:02 PM   #2
unSpawn
Moderator
 
Registered: May 2001
Posts: 27,470
Blog Entries: 54

Rep: Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901Reputation: 2901
1. Ask yourself what "connecting to a box" means. What do you need server-side to be able to connect to a port? An open port. What is an open port? A port that allows receiving traffic. Why does it allow receiving traffic? Because server-side there is an application which is listening on that port. What if I have a daemon running and the port registers as closed? Then there's no daemon listening, or it's firewalled. What if I have a daemon running and the port registers as filtered? Then it's firewalled. If a port is open, but is marked as filtered in nmap, can I connect to it? No. Are there any other ways to still be able to connect to a filtered port? Try reading something that includes the phrase "trusted hosts".

2. Safe considering what? If your ftpd has no built-in mechanisms to allow/deny hosts/ranges access then, yes if it has TCP Wrappers support or is run tru xinetd then it is your only option besides proper firewalling. Remember you don't have to worry about the world being able to connect to your box, but now you have to worry about who connects to you from those allowed hosts :-]

Last edited by unSpawn; 11-02-2002 at 01:03 PM.
 
  


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
general security advise phsythax Linux - Security 4 11-27-2005 09:55 AM
general security une Linux - Security 3 05-02-2005 08:08 AM
General Security ajbrouwe Linux - Security 3 07-14-2004 03:02 PM
General Linux security overview dscapuano Linux - Security 2 06-24-2004 10:44 AM
General Security Config Yapok Linux - Security 3 10-02-2001 07:02 AM


All times are GMT -5. The time now is 12:09 AM.

Main Menu
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
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration