From: "Gáspár Lajos" <swifty@freemail.hu>
To: Petr Pisar <petr.pisar@atlas.cz>
Cc: netfilter@vger.kernel.org
Subject: Re: DHCP works but iptables should have dropped
Date: Mon, 15 Oct 2007 14:03:44 +0200 [thread overview]
Message-ID: <47135720.9040804@freemail.hu> (raw)
In-Reply-To: <slrnfh5249.8cf.petr.pisar@album.ics.muni.cz>
[...]
> Use "netstat -lnp |grep dhcp". You can see that dhcpd has open 2 sockets.
> One is UDP socket for reply packet transmission, the second one is raw
> socket for request recieving.
>
> The raw socket has one important attribute: it recieves packets before
> netfilter. The same mechanism is used by tcpdump/libcap.
>
>
Are you saying that We CAN NOT "protect" the DHCP-server with iptables?
> Therefore dhcpd can recieve packet even if they are blocked by
> netfilter. This is feature, not a bug. I have not idea why ISC' DHCP
> sever is implemented in this manner, but it is. (May be because of indirect
> broadcast destination IP address in DISCOVERY client request.)
>
> -- Petr
>
Swifty
next prev parent reply other threads:[~2007-10-15 12:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-12 21:32 DHCP works but iptables should have dropped pockiman
2007-10-14 21:22 ` Petr Pisar
2007-10-15 12:03 ` Gáspár Lajos [this message]
2007-10-15 15:39 ` Petr Pisar
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