Re: Fork bombing a Linux machine as a non-root user

From: Jeff Kinz (jkinz_at_kinz.org)
Date: 03/19/05

  • Next message: Jonathan Ryshpan: "First wish for FC4 x86_64: Separate mumbli-config files for 64-bit and 32-bit libs"
    Date: Sat, 19 Mar 2005 11:42:17 -0500
    To: "M.Rudra" <dr.rudra@gmail.com>, For users of Fedora Core releases <fedora-list@redhat.com>
    
    

    On Sat, Mar 19, 2005 at 05:03:38AM -0500, M.Rudra wrote:
    > At our hospital we have a proper system with Linux servers and
    > backups, staff use a windows-like software custom built to our
    > requirements.
    > Its the home connection that was attacked twice online so I want to
    > install software to secure my home machine.
    >
    > This Iptable faq mentions that 2 ethernet cards are required to setup
    > a fire wall.
    > http://newbiedoc.sourceforge.net/networking/homegateway.html
    >
    > Is there an alternative to iptables as i dont have 2 cards and how do
    > i get my kernel version? if my kernel is below 2.4 version is there
    > any other firewall option on Fedora.
    > i tried a command with this result " bash: modprobe: command not found
    > " ... actually most commands as a user give above result.
    > thanks for your time.

    Hi MR,
    Iptables can be used with one Ethernet card (AKA 'Network Interface
    Card' = "NIC"). However the single NIC configuration will only protect
    the single machine which is running iptables.

    Does your home network look like either of these two configurations?

    "----" = an ethernet cable

    setup A:

       Internet single
      cable/DSL--------------------------- Computer
       device

                              
    setup B:
                              |---------- Computer 1
       Internet |
      cable/DSL------ethernet |----------- Computer 2
       modem router |
                              .
                              .
                              |----------- Computer "N"

    Note - In setup "B" when using DSL, there are some devices which merge
    the functionality of a DSl modem and a router.

    To use Iptables in the most desirable fashion the config seen below is
    needed. Note that it requires a dedicated standalone PC to use as the
    firewall.
                              
    setup C:
                                               |-------- Computer 1
       Internet old PC Cheap |
      cable/DSL------w/Linux----- Ethernet-----|-------- Computer 2
       modem iptables Hub( or a |
                     (2 Nics) router) .
                   (Firewall) .
                                               |-------- Computer "N"

    There is a compromise to setup C which uses the Firewall machine both as
    a firewall and a user workstation. This setup still requires two NICs
    but does not require any more additional computers than what you have
    now. While it is not the setup recommended by security experts it will
    perform the task of firewalling your home environment.

    Does your home setup resemble "A" or "B" above? What, if anything is
    different about it?

    -- 
    "The only system which is truly secure, is one which is switched off
    and unplugged, locked in a titanium lined safe, buried in a concrete
    bunker, surrounded by nerve gas and very highly paid armed guards. Even
    then, I wouldn't stake my life on it" - Gene Spafford 
    (Good thing. the law of unintended consequences: A laptop, w/wireless
    NIC and wake on "date" set in the BIOS)
    http://kinz.org
    http://www.fedoranews.org
    Jeff Kinz, Emergent Research, Hudson, MA.
    -- 
    fedora-list mailing list
    fedora-list@redhat.com
    To unsubscribe: http://www.redhat.com/mailman/listinfo/fedora-list
    

  • Next message: Jonathan Ryshpan: "First wish for FC4 x86_64: Separate mumbli-config files for 64-bit and 32-bit libs"

    Relevant Pages

    • RE: A question about a basic security setup...
      ... A question about a basic security setup... ... > I was thinking of running iptables on the dual homed host, ... What you are looking for here, is an "application proxy" type firewall. ...
      (Security-Basics)
    • Re: firewall ??
      ... > I already have a DHCP server, but it's not on the firewall box. ... iptables -F INPUT ... # Setup stuff you're allowing to talk outbound from the firewall ...
      (Fedora)
    • Re: I like SNORT but I need a Firewall as well (GUI for IPChains/Tables))
      ... Another one is to take the time to put together your own iptables script by ... When I setup a firewall/router on my ancient non-X laptop I used a setup ... You do know that ipchains/tables *is* the firewall, ...
      (comp.security.firewalls)
    • Re: I like SNORT but I need a Firewall as well (GUI for IPChains/Tables))
      ... Another one is to take the time to put together your own iptables script by ... When I setup a firewall/router on my ancient non-X laptop I used a setup ... You do know that ipchains/tables *is* the firewall, ...
      (comp.os.linux.security)
    • Re: Problem about ppp -nat
      ... ipfw firewall, ... Just setup your fw of choice as if the tun0 device is the external device and leave all the nat stuff completely out of it. ... My Internet interface is rl0, ... # /etc/rc.d/routing restart ...
      (freebsd-questions)