From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 16 Sep 2004 14:06:15 -0700 From: Stephen Hemminger Subject: Re: [Bridge] Setting the interfaces in promiscuous mode Message-Id: <20040916140615.3aee9580@dell_ss3.pdx.osdl.net> In-Reply-To: <5f3f2c61040916134370cc8897@mail.gmail.com> References: <5f3f2c610409160928252d34b1@mail.gmail.com> <20040916110955.6347a4e9@dell_ss3.pdx.osdl.net> <5f3f2c61040916134370cc8897@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Lionel Litty Cc: bridge@lists.osdl.org On Thu, 16 Sep 2004 16:43:40 -0400 Lionel Litty wrote: > > promiscuous mode is tracked in the kernel with a counter, the kernel > > won't change the actual hardware until the counter goes to zero. This is > > why running something like tcpdump which changes interface to promiscuous mode > > will have no effect on the bridge. How did you > > force the interface out of non-promiscious mode? You may not changed anything. > > > > I simply did "ifconfig eth0 -promisc" and "ifconfig tap0 -promisc". > "ifconfig" then no longer indicates that the interfaces are in > promiscuous mode. Are you saying that the output of ifconfig is not > reliable and that the interfaces may in fact still be in promiscuous > mode? This would make sense, but then how come the performance seems > to be affected by the change? Because when the stack thinks it is in promiscious mode then all the packets have to be processed. > > Also promiscuous on tap means nothing really since there is no hardware > > filtering. > > OK. I thought there might have been some software simulation of the > promiscuous mode. > > Thanks, Lionel.