Date: Mon, 17 Jan 2011 19:03:27 +0100 From: Monthadar Al Jaberi <monthadar@gmail.com> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-net@freebsd.org, freebsd-mips@freebsd.org, "Jayachandran C." <c.jayachandran@gmail.com> Subject: Re: capturing packet from wlan0 with netgraph? Message-ID: <AANLkTin%2BJFF-5TtvyzERLc2A2oWinhrhnq32LCskXa=Q@mail.gmail.com> In-Reply-To: <AANLkTi=GPxqSkEt4jkFh%2Bnr2%2BbmN7oTB7cJ3cWqtEw5R@mail.gmail.com> References: <AANLkTi=s45woPE21exHgArAyAaO2sW%2BeR=%2BumB6zZcr5@mail.gmail.com> <AANLkTikC1nYudfM91rPxFfgCj83m8YbdagedeydyBaue@mail.gmail.com> <AANLkTikgdf4Uy20NF6vQ=-NWGYS4LDdmypKng=2Bg2ME@mail.gmail.com> <AANLkTi=Wu=sgH76vHx-4CmaUgm_H9FMA9Nuvbgk4Gkzz@mail.gmail.com> <AANLkTik4HtAX7MtT4dVbHku-bfVLun_C%2BnRsbL13SrHu@mail.gmail.com> <AANLkTi=GPxqSkEt4jkFh%2Bnr2%2BbmN7oTB7cJ3cWqtEw5R@mail.gmail.com>
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filed a PR http://www.freebsd.org/cgi/query-pr.cgi?pr=3D154091 On Mon, Jan 17, 2011 at 6:43 AM, Adrian Chadd <adrian@freebsd.org> wrote: > Hi, > > Please file a PR about this and the output of "show registers". > > I bet that the ip pointer isn't aligned at that point in the code. > Whatever is passing the packet to the IP layer should be re-aligning > things beforehand. > (eg, look at what the ethernet ipfw hook code does - if the ether type > is ipv4/ipv6, it actually realigns the packets before passing it back > up the stack.) > > > > Adrian > > On 13 January 2011 16:25, Monthadar Al Jaberi <monthadar@gmail.com> wrote= : >> sorry but I have not worked with this for a while now, After some >> thoughts I dont think using netgraph will do me any good, because >> traffic can still flow through the antennas of the cards. >> >> If you think it would still be useful to see more ddb prompt for other >> scenarios I am happy to try and supply that, but I won't have some >> free time until late tomorrow :) >> >> thnx again! >> >> On Thu, Jan 13, 2011 at 7:53 AM, Adrian Chadd <adrian@freebsd.org> wrote= : >>> I've encountered this before. >>> >>> The mbuf's there aren't always aligned at this point. >>> >>> >>> >>> Adrian >>> >>> On 13 January 2011 14:17, Jayachandran C. <c.jayachandran@gmail.com> wr= ote: >>>> On Thu, Jan 13, 2011 at 11:08 AM, Adrian Chadd <adrian@freebsd.org> wr= ote: >>>>> Find out what the address is that's causing the problem. There's >>>>> plenty of places where unaligned mbuf's exist in the IP code and >>>>> aren't correctly realigned before being touched. >>>>> >>>>> MIPS people - is "address error" an alignment problem? >>>> >>>> Address error can be an alignment problem (or some other cases like >>>> accessing kernel address from userspace). >>>> >>>> But looking at the crash, it certainly seems like in ip_input, the lin= e >>>> =A0 =A0 435 =A0 =A0 =A0 =A0 if (ip->ip_v !=3D IPVERSION) { >>>> >>>> got a bad address for the ip pointer. >>>> >>>> The output of 'show registers' at the ddb prompt would be useful to >>>> debug further. >>>> >>>> >>>>> On 30 December 2010 21:47, Monthadar Al Jaberi <monthadar@gmail.com> = wrote: >>>>>> Hi, >>>>>> >>>>>> I have an idea in my head and would like to know if it is possible. >>>>>> >>>>>> I want to simulate and test the net80211 mesh code in FreeBSD Curren= t. >>>>>> I have an RSPRO board with 3 atheros cards. >>>>>> >>>>>> My =A0basic idea is to run three jails each having its own network >>>>>> stack, and redirect all data packets coming out/in of the wlan drive= r >>>>>> to a Server running a home brew application that simulates the mediu= m. >>>>>> That would be great, right? Realtime unchanged code to test, running >>>>>> different application in their own jails. >>>>>> >>>>>> So first I started to test netgraph with a simple test case, I want = to >>>>>> receive all packets from one wireless card and see the data in >>>>>> wireshark or tcpdump... >>>>>> >>>>>> This is my netgraph code: >>>>>> mkpeer wlan0: hub lower hook0 >>>>>> name wlan0:lower hub >>>>>> connect hub: wlan0: hook1 upper >>>>>> connect hub: arge0: hook2 lower >>>>>> >>>>>> >>>>>> So if I understood man ng_ether correct, this should capture >>>>>> everything from wlan and redirect to ethernet cable. >>>>>> >>>>>> But I get a panic after a couple of seconds: >>>>>> Trap cause =3D 4 (address error (load or I-fetch) - kernel mode) >>>>>> [ thread pid 11 tid 100037 ] >>>>>> Stopped at =A0 =A0 =A0ip_input+0xd8: =A0lw =A0 =A0 =A0v0,0(s0) >>>>>> >>>>>> I suspect that data flows to all hooks of the hub, and that is a bad >>>>>> thing right? Need to create a special hub node to filter data? Or >>>>>> maybe use two ethernet cables for out resp. in? >>>>>> >>>>>> Is it even possible to do what I want? Or am I thinking wrong? And i= s >>>>>> there a simpler way? >>>>>> >>>>>> What I want is to test mesh code in a bunch of FreeBSD systems witho= ut >>>>>> moving the hardware, one could just stack RSPROs and connected them = a >>>>>> big switch and a PC. >>>>>> Hope was I clear in my thoughts. >>>>>> >>>>>> Best regards, >>>>>> -- >>>>>> //Monthadar Al Jaberi >>>> >>>> JC. >>>> >>> >> >> >> >> -- >> //Monthadar Al Jaberi >> > --=20 //Monthadar Al Jaberi
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