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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=47135720.9040804@freemail.hu \
--to=swifty@freemail.hu \
--cc=netfilter@vger.kernel.org \
--cc=petr.pisar@atlas.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.