DHCP Client Debug Verbosity

Russell Dekema dekemar at umich.edu
Tue Nov 24 12:21:04 UTC 2015


On Tue, Nov 24, 2015 at 7:00 AM, Simon Hobson <dhcp1 at thehobsons.co.uk> wrote:
> Russell Dekema <dekemar at umich.edu> wrote:
>
>> This (offers getting dropped by iptables rules) definitely applies to
>> the DHCP client - at least when using DHCPv6. I learned that the hard
>> way last week on an unrelated case, and I don't see why it would be
>> any different with v4.
>
> It's considerably different between IPv4 and IPv6.
>
> In IPv6, the client self-configures a link-local address and uses that during solicitation. So all traffic is "normal" IP packets that can go through the normal IP stack - and hence always through iptables.
> With IPv4 it's very different. Prior to getting an address and configuring the interface, the DHCP client has to work with an unconfigured interface and so the requirement to use raw sockets - thus bypassing the IP stack and (I think) iptables rules.

Ahhh, right; good point!


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