Making wpa_supplicant work with dhclient on Fedora

Jouni Malinen j
Tue Jun 3 01:22:25 PDT 2008

On Mon, Jun 02, 2008 at 05:07:19PM -0400, Pavel Roskin wrote:

> I like the idea of running dhcplient from wpa_supplicant.  It follows
> the approach to configure the interface from the lower level to the
> upper level.
> Normally, the interface is brought up, then dhclient is run or static IP
> is configured.  To accommodate layer 2 configuration, bringing up the
> interface should run wpa_supplicant, and if wpa_supplicant succeeds, it
> would run dhclient.

Why would wpa_supplicant need to run dhclient? I could kind of
understand this if the IP configuration (DHCP vs. static) would be set
based on the wireless network (e.g., some networks are using DHCP while
others use static configuration), but even that case may be handled
better with something else taking care of running dhclient (or setting
IP addresses). Anyway, if the interface is always configured to use DHCP
(which, I would assume, is the most common case), I would just consider
leaving DHCP client running all the time. This, of course, requires that
the DHCP clients knows how to figure out when there is need to verify
that the current configuration is still valid (e.g., ARP ping the
default gateway) and if needed, request new IP configuration.

> Layer 2 configuration is not just for wireless networks.  It may be a
> wired network with 802.1x.  Serious distributions should be able to get
> it right.

As far as IEEE 802.1X PAE is concerned, operstate (RTM_SETLINK,
IFLA_OPERSTATE) was added. If the DHCP client were to follow this state,
it should be able to handle DHCP requests at proper time (i.e., when the
802.1X port is open).

I would like to make sure that wpa_supplicant generates suitable events
to allow other daemons to take care of IP configuration needs in all
possible cases. As far as I know, such events are already generated (but
not necessarily used by other daemons). If not, I would like to know
what exactly is missing.
Jouni Malinen                                            PGP id EFC895FA

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