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SubjectRe: 2.2 breaks DHCP, FUD or not ??
Yes and no, Its correct to say the previous versions of DHCP will not work
with 2.1.x and higher, you can however cure that problem and grab a newer
version of DHCP, its available from redhat's contrib. You need the file
dhcp-client-2.0b1pl0-3.i386.rpm, assuming you are running redhat or have
rpm installed. Im sure you can find a non rpm version out there somewhere,
im just not sure where.



On Sat, 22 Aug 1998, Lauri Tischler wrote:

> I found this on 'dhcp-server' list. Plse tell me it's not true and
> that I'm just an ignorant victim of FUD.
>
> [QUOTE]
> >
> > No, unfortunately 2.1 (and therefor 2.2) actually breaks DHCP very
> > badly. The server isn't too badly impacted, but the client is
> > completely screwed. You see, BPF isn't the "right" way to do
> > multiple interfaces - it's just a way that works consistently on a lot
> > of platforms. Some platforms, including (at least) Linux, BSD/os and
> > SCO Unix, provide a way to do multiple interfaces and still use the
> > BSD sockets API. They do this by extending the API - in the Linux
> > case, sockets are bound to hardware interfaces, and you only receive a
> > packet if you have a socket bound to that interface (or an unbound
> > socket), so it's easy to tell where packets come from. BSD/os and
> > SCO put tags on packets that you can read from userland, so that you
> > can tell where a packet came from without having multiple sockets.
> >
> > Using the BSD sockets API is The Right Thing To Do. There's no
> > excuse for meddling down at the low level with BPF, as we currently
> > do, other than that we must, in order to make multiple interfaces
> > work. When you meddle at the low level, you have to take into
> > account the low-level details, like framing, which differ between
> > different hardware types (e.g., Ethernet, Token Ring, FDDI). So
> > platforms that use BPF or equivalents work really well if you happen
> > to have an ethernet network, but fail miserably if you're using FDDI
> > or Token Ring. Fortunately, this isn't a problem that most people
> > run into.
> >
> > So why is Linux 2.1 a problem? The Internet Software Consortium DHCP
> > Distribution uses a common code base for the client and server. When
> > you build them, you only get one copy of the common code. So the
> > client and server are pretty much forced to use the same networking
> > API. This could be worked around, but one wonders why - it makes a
> > lot of sense to use a common API, and if you can't, I think there's
> > something wrong.
> >
> > Linux 2.1 does two things that break the client. The first is that
> > it's no longer legal to configure an interface with an IP address of
> > 0.0.0.0. Of course, DHCP and BOOTP operate on the premise that this
> > is possible, and that if you do it, the stack will do some fiddling
> > for you to make things work. When this feature is taken away, you
> > are pretty much forced to use BPF. On the BSDs, this isn't a bad
> > thing, because you're using BPF anyway. On Linux, this is a really
> > bad thing - Linux currently has the distinction of being the _only_
> > operating system on which the ISC DHCP networking glue works
> > correctly, and it's about to lose this distinction because of this
> > feature removal.
> >
> > The other bug in 2.1 is that it used to be you could get a list of
> > interfaces with the SIOCGIFCONF ioctl. In Linux 2.1, SIOCGIFCONF
> > only returns the list of interfaces that already have IP addresses.
> > When you're implementing a DHCP client, whose purpose in life is to
> > acquire IP addresses for interfaces, this is an important and
> > unfortunate change.
> >
> > So, sorry to rain on your parade, but Linux 2.1 is a _disaster_ for
> > DHCP support. :'(
>
> [/QUOTE]
>
> Cheers..
> --
> Lauri Tischler, Network Admin Tel: +358-9-47846331
> EFORE Oyj Fax: +358-9-47846500
> Piispanportti 12 (PL 61) Mobile: +358-40-5569010
> 02211 Espoo FINLAND EMail: lauri.tischler@efore.fi
> * High Quality Custom Designed Power Supplies and Rectifiers *
>
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