hi,On 5/7/07, Doris Jung <Doris.Jung@xxxxxxxx> wrote:> Hi,>> I answered your questions below.>> Regards>> Doris>> Parag N(पराग़) wrote:> > Hi,> > On 5/7/07, Doris Jung <Doris.Jung@xxxxxxxx> wrote:> >> Hi,> >>> >> I have the following problem:> >>> >> I'm working on a CarPc with Debian 2.6.15.> >>> >> I have to send and receive packets ( i.e. ping) from an own written> >> kernel module (I call it umts with the intercae umts0) to ppp0, which> >> has a connection to an umts modem via the nozomi driver. With each new> >> connection with the provider the ppp0 receives a new loacal address i.e.> >> 90.187.103.249.> >>> >> I configured umts 0 with "ifconfig umts0 10.0.0.10 netmask> >> 255.255.255.0 "> >> and set it as default route with "route add default gw 10.0.0.10"> >>> >> For sending the packets from umts0 to ppp0 I use the following code:> >>> >> struct net_device *dev_ppp0;> >> dev_ppp0 = dev_get_by_name("ppp0");> >> skb->dev = dev_ppp0;> >> skb_pull(skb, 14);> >> *((skb->data)+12) = 90;> >> *((skb->data)+13) = 187;> >> *((skb->data)+14) = 103;> >> *((skb->data)+15) = 249;> >> skb->nh.iph->check = 0;> >> skb->nh.iph->check = ip_fast_csum((unsigned char *)skb->nh.iph,> >> skb->nh.iph->ihl);> >> skb->pkt_type = PACKET_OUTGOING;> >> dev_queue_xmit(skb);> >>> >> I changed the IP source address from 10.0.0.10 to 90.187.103.249 so that> >> ppp0 can receive the reply for the ping.> >>> >> I switch the ip forwarding on:> >> echo 1 >> /proc/sys/net/ipv4/ip_forward> >> cat /proc/sys/net/ipv4/ip_forward> >> 1> >>> >> With the code above I can receive the reply for the ping at ppp0 (seen> >> with "tcpdump -i ppp0 -x -e -vvv") but I don't know what I have to do to> >> receive the ping reply packet with my umts module.> >>> >> I read> >> http://kernelnewbies.org/Documents/LinuxIPNetworking#head-f204e85ca7561a0a903c6a94273b9ee7a27b4994.> >>> >> and I have learned the following:> >> When a packet is received the IP layer checks whether the packet is> >> for the own host (I think that's my case) or for another host. If it's> >> for the own host the packet is sent to the transport layer. But in my> >> case the packet shouldn't be sent to the transport layer but to my> >> kernel module umts.> >> > I will need more input to answer this query. You mean you connected> > to internet by dialing umts modem and as its umts service each time> > you dial modem you are going to receive a new IP right?> Yes> > Now you> > created umts0 new network interface and trying to send packets from> > umts0 to ppp0 to outside network?> Yes> >> > You may need to use netfilter hooks to check if a packet received> > at ppp0 need to be forwarded to umts0 then code it to change> > destination IP from 90.187.103.249 to 10.0.0.10> > I assume I understood what you want if not reply with more> > explanation.> Yes: ppp0 receives the packets and these packets should be transmitted> from 90.187.103.249 to 10.0.0.10. If I use netfilter for this, how can I> use it and which function of my umts kernel module can receive this> packet.You would like to go throughhttp://www.phrack.org/archives/61/p61-0x0d_Hacking_the_Linux_Kernel_Network_Stack.txt
Is it the hard_start_xmit function of my device? Or can or have> I to register an additional function for the packets from outside?Regards,Parag.��.n��������+%����w�j)p���{.n����z�ޖw�n'���q���b�������v��m�����Y�����
