On Fri, 6 Jun 2003 15:04:49 -0400 "Fu Ming" <[EMAIL PROTECTED]> wrote:
> > ----- Original Message ----- > From: "Remco Post" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Friday, June 06, 2003 4:15 AM > Subject: Re: where the ip packet is discarded? > > > > On 6 Jun 2003 09:26:00 +0800 > > "forge" <[EMAIL PROTECTED]> wrote: > > > > > Hello, everyone > > > > > > I have a hub and several computers connected to it, e.g. > > > > > > HUB > > > |----B > > > A ---| > > > | > > > |----C > > > > > > > > > Now, when A sends a packet to B, C will also receive the packet > > > on datalink layer. > > > But the packet is discarded before it reaches ip_input(). > > > I think it's discarded in datalink layer because the MAC address > > > is not matched. > > > > > > Now I tried to find the function discarding the unmatched packets, > > > but I failed because I'm not familiar to the code in datalink > > > layer. > > > > > > > Usually, the ethernetcard takes care of that. This has a hardware > > filter that is programmed with the mac from a config rom on the NIC. > > That is why you can set your mac-address. If you subscribe to a > > ethernet multicast address (rarely used) the crc of the ethernet > > multicast is matched in a smart filter. A NIC can be set to > > promiscues mode to accept all packets, > in > > that case, the IP layer has to do all the filtering... > > Does this means that a multi-homed FreeBSD will start to route packets > on its connected network if its NICs were in promiscues mode? I don't > believe so. I think only the BPF devices are affected, not ip_input. > routing is layer 3 and has nothing to do with NICs being promiscue or not. Even better, for routing you don't need the nic to be in promiscues mode.... > > > > > I use FreeBSD 4.5 system and can anyone give me some advice? > > > > > > Much thanks. > > > Forge > > > > > > > > > -- > > Met vriendelijke groeten, > > > > Remco Post > > > > SARA - Stichting Academisch Rekencentrum Amsterdam > > http://www.sara.nl > > High Performance Computing Tel. +31 20 592 8008 Fax. +31 20 668 > > 3167 > > > > "I really didn't foresee the Internet. But then, neither did the > > computer industry. Not that that tells us very much of course - the > > computer > industry > > didn't even foresee that the century was going to end." -- Douglas > > Adams > > >
