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Re: [suse-security] Is it iptables enough?



Hi John,

that's also perfectly easy unless your 2 boxes are connected with a cross-over-cable directly, but then you wouldn't need iptables ;-). The packages have to go through some hubs, switches or routers and there are always ways to find out who's talking to whom. As I said - it just depends on how valuable the information transfered is and on how good it's protected. But to be not too paranoid (although there is no such thing as being too paranoid) - for most cases to filter by IP and MAC-Address should be perfectly suited, if you're not running bank-transfers over it ;-).

Greetings,

Ralf



John wrote:
----- Original Message ----- From: "-linux_lad" <john@xxxxxxxxxxxx>
To: "Geoffrey" <esoteric@xxxxxxxxxxxx>
Cc: <suse-security@xxxxxxxx>
Sent: Monday, February 02, 2004 7:55 PM
Subject: Re: [suse-security] Is it iptables enough?



On Mon, 2 Feb 2004, Geoffrey wrote:


John wrote:

Thanks Ralf.

Definitely, mac spoofing is quite hard, isn't?

Depending on the hardware, it's not difficult at all.  See the -H option

at:

 http://www.scyld.com/diag/


Mac spoofing is quite easy to do. It can easily be accomplished even by
amateurs. Most low end firewalls and routers offer it as a feature to
circumvent PPOE restrictions on single MAC addresses.


Can iptables be cracked? What vulnerabilites exist regarding iptables?

I am not aware of any documented case of IP Tables failing. It's easy to
misconfigure your firewall script, however. IPTables operates at the
kernel level, and it's conceiveable that some clever shithead could write
a kernel module that alters IPTables' behavior in a way that nullifies
it's protection of your server. Remember, a rootkit gives anyone who
accesses it absolute power over the server to do anything they want,
including poisoning your detection mechanisms.

 There is no such thing as perfect security. The best you can hope for is
"adequate", and adequate is defined on a constantly changing sliding
scale. Additionally, most of the time confirmation that your security
policy is inadequate or insufficient comes after a breakin.

Apply the tightest policy your users and management will allow, and
constantly push for tighter control of the network. You will not regret
it.

--
-linux_lad
ICQ 115601915
pub key on request


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Allright, how can an attacker detect the mac address that i permit to
connect to my system (or even an ip address (ip spoof))?

Is there any tool or tecknik, or something like that?

Thanks in advance!





--
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Ralf Ronneburger
ralf@xxxxxxxxxxxxxx

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