From: Aleksandar Milivojevic <amilivojevic@pbl.ca>
To: netfilter@lists.netfilter.org
Subject: Re: No internet connection
Date: Thu, 09 Sep 2004 12:00:28 -0500 [thread overview]
Message-ID: <41408C2C.6020208@pbl.ca> (raw)
In-Reply-To: <20040909160053.GN8419@metastasis.org.uk>
Nick Drage wrote:
> Not wishing to be paranoid, buuuuuuuuutttttttt..... couldn't you
> usefully restrict those by source and destination IP?
Probably, but... You usually don't know IP address of DHCP server in
advance (ISP can chage it without prior notice, which will happen each
time they deem it is time to reorganize their network). You don't know
what will be your address before it is assigned to you.
Theoretically, you could modify dhcpclient so that it opens up firewall
to be more permissive for those two ports when initially getting IP
address, and than making it more strict when both local and DHCP
server's addresses are known (and making it more permissive again if
DHCP server goes south, so that new one could be discovered).
Theretically, your ISP (I guess it's cable, if using DHCP) should have
been protecting you anyhow. Otherwise, any wise ass with Windblows or
Linux box could screw up entire cable segment. It would be the last
thing he would do (since it would be trivial to pinpoint him). But it
might be considered as fun last thing by the before mentioned wise ass.
On the other hand, you should also assume ISP is brain dead and have
everything misconfigured (or in better case, not configured at all ;-)
--
Aleksandar Milivojevic <amilivojevic@pbl.ca> Pollard Banknote Limited
Systems Administrator 1499 Buffalo Place
Tel: (204) 474-2323 ext 276 Winnipeg, MB R3T 1L7
next prev parent reply other threads:[~2004-09-09 17:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20040909144044.27300.qmail@web50208.mail.yahoo.com>
2004-09-09 15:02 ` No internet connection Jason Opperisano
2004-09-09 16:00 ` Nick Drage
2004-09-09 16:25 ` Jason Opperisano
2004-09-09 17:00 ` Aleksandar Milivojevic [this message]
2004-09-10 14:49 No Internet Connection Giancarlo Boaron
2004-09-10 15:33 ` Jason Opperisano
2004-09-10 16:41 ` Aleksandar Milivojevic
2004-09-10 16:56 ` Jason Opperisano
2004-09-10 17:24 ` Aleksandar Milivojevic
2004-09-10 17:28 ` Giancarlo Boaron
-- strict thread matches above, loose matches on Subject: below --
2004-09-09 14:06 No internet connection Piszcz, Justin Michael
2004-09-09 14:04 Giancarlo Boaron
2004-09-09 14:15 ` Jason Opperisano
2004-09-09 16:02 ` Nick Drage
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