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Re: Basic question about ipchains being useful



Julien Dupre wrote on Tue Jun 19, 2001 at 11:14:06PM:
 
> I'm using these packages with the latest versions in stable : postfix,
> apache 1.3.9 (quite old btw but not necessarily a problem), bind
> 8.2.3, openssh 1.2.3

[...]
 
> My idea is not to look at security alerts but trust that debian
> maintainers will do it, I have a daily cron job which mails me if
> "apt-get -s upgrade" says something should be upgraded, is this not
> reasonable ?

hopefully, security.debian.org is in your /etc/apt/sources.list?

> Is there any case where a package with a known exploit
> was not upgraded quickly in stable ?
> 
> > ) with ipchains/iptables you have a choice of accepting, rejecting
> > or dropping packets. If you reject them, they know you exist. If you
> > drop them, they have to wait for a timeout before they know anything
> > about you - you can play dead.
> 
> Yes but what should I want to drop them, as I would only deny packets
> for services I'm not running, a potential attacker would just get a
> timeout for services which aren't running anyway.

You've got the point. I had to learn that there is no sense in dropping
packages instead of rejecting them. And ... once you offer services you
cannot play dead anyway.

> Rigth, but more generally about the interest of ipchains : if I have
> to consider such packets are dangerous, it means that opened service
> are not secured, can't I just rely on having most recent versions
> installed and be confident but for zero day exploits ?

Simple rule: reject anything that is not essential for the services you 
are offering. Put yourself in paranoia-mode while building your firewall.

Matthias

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