Date: Fri, 08 Mar 2002 15:47:42 +0530 From: "Rajesh P Jain" <rpjain_1977@eudoramail.com> To: "Robert Watson" <rwatson@FreeBSD.org> Cc: freebsd-hackers@FreeBSD.org Subject: Re: BPF - Locally Generated Packet Reception Message-ID: <FJAFLEOEPFFMCAAA@shared1-mail.whowhere.com>
next in thread | raw e-mail | index | archive | help
Hello, Thank you very much for your reply. BIOCSSEESENT ioctl works fine with the Ethernet interface. But this ioctl does not work for the 'tun' (user PPP of FreeBSD) device. I have seen bpf code also. 'bpfioctl' function sets the d->bd_seesent flag to the value which is passed for this BIOCSSEESENT. In bpf_mtap also checks for this variable and ( m->m_pkthdr.rcvif == NULL ) As you had told in your earlier mail, the received interface is not null for our case. Any help on this would be greatly appreciated. -Raj -- On Wed, 6 Mar 2002 23:08:55 Robert Watson wrote: > >It could be that this fails for interfaces that perform hardware loopback, >since it relies on the behavior of software loop. There may also be some >other circumstances where this occurs. Basically, the BPF device can tell >it's "locally sourced" because it has a NULL interface pointer associated >with it. If the packet ends up with a none-NULL interface pointer for >some reason, it will be considered a non-locally sourced packet. In >practice, we've used this successfully on a variety of ethernet devices -- >which interface type are you using? > >Robert N M Watson FreeBSD Core Team, TrustedBSD Project >robert@fledge.watson.org NAI Labs, Safeport Network Services > >On Wed, 6 Mar 2002, Rajesh P Jain wrote: > >> Hi, >> In the BPF - Berkeley Packet Filter, when a file descriptor is associated to an interface to send and receive packets, there is an ioctl parameter "BIOCSSEESENT", which is by default set to 1. Hence the packets both from "remote systems" and "locally generated" are received. >> >> If "locally generated" packets needs to be filtered, we can use the option "BIOCSSEESENT" and set the value to 0. >> >> But even after setting this value to 0 (using the ioctl call), the "locally generated" packets are received. >> >> Am I missing something ? Plese throw light on this issue. >> >> TIA >> Raj >> >> >> Join 18 million Eudora users by signing up for a free Eudora Web-Mail account at http://www.eudoramail.com >> >> To Unsubscribe: send mail to majordomo@FreeBSD.org >> with "unsubscribe freebsd-hackers" in the body of the message >> > > Join 18 million Eudora users by signing up for a free Eudora Web-Mail account at http://www.eudoramail.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?FJAFLEOEPFFMCAAA>