From owner-freebsd-questions Thu Jul 22 15:48:34 1999 Delivered-To: freebsd-questions@freebsd.org Received: from alicia.nttmcl.com (alicia.nttmcl.com [216.69.69.10]) by hub.freebsd.org (Postfix) with ESMTP id 9115B15647 for ; Thu, 22 Jul 1999 15:48:30 -0700 (PDT) (envelope-from divya@nttmcl.com) Received: from localhost by alicia.nttmcl.com (8.8.5/3.5W(96/10/22)) id PAA27289; Thu, 22 Jul 1999 15:47:09 -0700 (PDT) Date: Thu, 22 Jul 1999 15:47:08 -0700 (PDT) From: Divya Mehra To: Brian Somers Cc: Brian Somers , freebsd-questions@FreeBSD.ORG Subject: Re: bpf and user PPP ( tun0 ) In-Reply-To: <199907221104.MAA01143@keep.lan.Awfulhak.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Thanks for the value input ! I am still not clear about the following : Can tcpdump be used to capture ppp control packets ( req,ack etc) After starting ppp0 and a ping over it, tcdump could dump the ping packets. But I could not dump the PPP control packets. Is there some way to dump the ppp control packets ? Thanks, Divya ************************************************************************** Divyashikha Mehra NTT Multimedia Communications Laboratories Computer Systems Designer 250 Cambridge Avenue, Suite 205 650-833-3655 (Voice) Palo Alto, CA 940040, USA. mailto : divya@nttmcl.com *************************************************************************** On Thu, 22 Jul 1999, Brian Somers wrote: > > > I invoked the BIOSETIF command before actually reading the the ppp > > packets. > > > > 1) For tun0 i.e user PPP it returns error "Network down". > > Only after PPP is up can I proceed further ( IPCP phase up). So I could > > not capture any PPP packets. Is my approach correct ? > > As soon as ppp opens the tun device, it brings it UP. If you're > getting "Network down" this should mean that ppp isn't running on > that interface. > > > BIOGCGDLT returns DLT_NULL . Is that correct ? should it not be > > returning DLT_PPP ? > > Dunno, I've never gone near the bpf device - tcpdump is the height of > my knowledge in this area. However, DLT_NULL makes a lot of sense as > bpf has no clue what's got the tun device open. > > > 2) For ppp0 what should BIOGDLT be returning ? > > I don't know much about the ppp interface - except that the code > stinks :-I I would *expect* DLT_PPP, but again, bpf doesn't know, so > I wouldn't be that surprised if it return DLT_NULL too. > > Disclaimer: I haven't looked at the if_ppp code to answer this, nor > do I want to ;^1 > > > thanks, > > Divya > > > > > > ************************************************************************** > > Divyashikha Mehra NTT Multimedia Communications Laboratories > > Computer Systems Designer 250 Cambridge Avenue, Suite 205 > > 650-833-3655 (Voice) Palo Alto, CA 940040, USA. > > mailto : divya@nttmcl.com > > *************************************************************************** > > > > > > On Tue, 20 Jul 1999, Brian Somers wrote: > > > > > > Hi, > > > > > > > > Can anyone tell me if bpf support user ppp packet ( tun 0 device) or it > > > > can be used only for kernel ppp ( ppp0 device ) ? > > > > > > Yes. > > > > > > > If it can support user ppp then what value should BIOSETIF be returning > > > > when bpf is to be used for reading ppp packets? > > > > > > >From the bpf man page: > > > > > > BIOCSETIF (struct ifreq) Sets the hardware interface associate with > > > the file. This command must be performed before any pack- > > > ets can be read. The device is indicated by name using > > > the ifr_name field of the ifreq structure. Additionally, > > > performs the actions of BIOCFLUSH. > > > > > > > Thanks, > > > > Divya > > > > > > > > ************************************************************************** > > > > Divyashikha Mehra NTT Multimedia Communications Laboratories > > > > Computer Systems Designer 250 Cambridge Avenue, Suite 205 > > > > 650-833-3655 (Voice) Palo Alto, CA 940040, USA. > > > > mailto : divya@nttmcl.com > > > > *************************************************************************** > > -- > Brian > > Don't _EVER_ lose your sense of humour ! > > > > --KAA00746.932634953/keep.lan.Awfulhak.org-- > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message