On Tue, Apr 27, 2004 at 01:50:11PM +0100, David Cannings wrote: > On Tuesday 27 April 2004 13:35, sschlesi@xxxxxxxxx wrote: > > I'm trying to stop broadcasts getting forwarded, but I'm not sure how > > to do this. i read that *.255 - which are afaik broadcast addresses - > > My first question is why are broadcasts getting forwarded anyway? Neither > ethernet or IP broadcasts should leave your subnet. How and where > exactly are broadcasts being forwarded? maybe he is bridging ? > > IP addresses ending in .255 are not always broadcast addresses. Any > subnet larger than class C (/24) can span more than one "block" of 256 IP > addresses. > > > doesnt guarantie that its a broadcast. then i read that its possible by > > matching the mac address, because broadcast will have ff:ff:ff:ff:ff:ff > > . but I'm not sure if that's all nonsense. > > There is the difference here between an IP broadcast and an ethernet > broadcast. IP broadcasts are sent to the ethernet broadcast address [1], > so you may be able to do a MAC match. > > According to the manual page I have here, the module "mac" only offers a > --mac-source option but there are more options in PoM I believe, you may > want to check the mailing list archives. > > David > > 1- A ping to the broadcast address on a LAN: > 13:44:59.765871 0:10:XX:XX:XX:XX Broadcast ip 98: 192.168.0.100 > > 192.168.0.255: icmp: echo request (DF) > >
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