Messages in this thread | | | Date | Tue, 22 Sep 1998 14:46:33 +0100 (GMT/BST) | From | Mike Jagdis <> | Subject | Re: xdm not seeing localhost |
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On Fri, 18 Sep 1998 root@ms2.inr.ac.ru wrote:
> > > It seems to be intentional. In the case of dummy it certainly > > > looks as though BROADCAST should be allowed. It is supposed to > > > behave like a real network interface isn't it? > > Not all real interfaces have broadcast flag set. > If it were true, this flag would be redundant 8)
True, but I said it should be *allowed* not set always. I can't see any way of changing the IFF_BROADCAST flag on an interface off hand.
Dummy interfaces are often used as place holders for interfaces which may not always be present - such as PC Card interfaces on lap tops. In such cases the dummy interface *must* behave like the real interface or things break.
> > - it breaks xdm > > Mmm... it does not break chooser.
Sure it does. XDMCP uses broadcasts to locate servers which might be willing to manage us. If you have no interfaces with the broadcast flag set (such as a lap top with only lo and dummy0) it can not see the local xdm. If my lap top is plugged in to the network it should list only the hosts running an XDMCP server. If I pull the PC Card so it switches to a dummy interface instead it should still list the local machine. It doesn't because the dummy interface does not have IFF_BROADCAST set. This is what we consider broken about it.
> > - it's incompatible to other U*X (*BSD and Linux 2.0) > > Sure? BSD has not IFF_BROADCAST on loopback 8)
Neither does SCO 3.2v5 (AFAIK). However this *is* a silent change from the 2.0 behaviour and *is* causing problems - especially since there seems to be no obvious work around.
> > are there any other programs which might need broadcasts on lo, too ? > > No valid programs need broadcasts on loopback.
But there *are* programs which need to have broadcasts on at least one non-external interface. If the *only* interface was lo it would not be completely unreasonable to want to set IF_BROADCAST even on that.
Mike
-- .----------------------------------------------------------------------. | Mike Jagdis | Internet: mailto:mike@roan.co.uk | | Roan Technology Ltd. | | | 54A Peach Street, Wokingham | Telephone: +44 118 989 0403 | | RG40 1XG, ENGLAND | Fax: +44 118 989 1195 | `----------------------------------------------------------------------'
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