Re: DHCP and iptables

From: lkml
Date: Mon Oct 12 2009 - 17:52:00 EST


Well, I just looked for "ethernet protocol" and read some things about DHCP again.

What's an ethernet protocol?

I also read, that "DHCP is built directly on UDP and IP" (RFC 2131).

It uses Ports (UDP 67/68) and the source address of the DHCP server is an IP address.

Could you answer me more in detail, why I get an IP, but block everything with iptables?

Sincerely yours Mathias Kub

--------------------
12.10.2009 Mathias Kub <lkml@xxxxxxxxx>

| Thank you very much for that quick reply.
|
| Yours Mathias Kub
|
| --------------------
| 12.10.2009 Arnd Bergmann <arndbergmann@xxxxxxxxxxxxxx>
|
| | On Monday 12 October 2009, lkml@xxxxxxxxx wrote:
| | > The last few days I have been wondering about the fact, that I get
| | > an IP address via
| | > DHCP if all chains at iptables are set to drop and no accept rules
| | > set.
| | >
| | > Does this happen on purpose?
| |
| | DHCP is an ethernet protocol, not an IP protocol, so you have to use
| | ebtables instead of iptables to filter it.
| |
| | Arnd <><
|
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