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Special Forums IP Networking Forwarding the IP packet from tun0 to/from eth0 Post 302317500 by johnniealan on Tuesday 19th of May 2009 06:40:59 AM
Old 05-19-2009
Forwarding the IP packet from tun0 to/from eth0

Hi all,

I am working on TUN/TAP for tunnelling IP packets from the application to the network.

I am able to open the tun device and assign the IP address to tun0. The steps I followed are given,

1. Opened the tun device /dev/net/tun
2. Assigned a IP address to the tun0 using ifconfig tun0 10.66.67.247
3. Added to the routing table using the following command route add -host 10.66.67.247 dev tun0
4. I have loaded the tun device using modprobe tun and I was able to see the device when I gave the command lsmod | sort
Code:
         tsdev                   7520  0 
         tun                    10336  1

5. the output of the command route is
Code:
10.66.67.247    *   255.255.255.255     UH    0      0        0 tun0
10.66.67.192    *   255.255.255.192     U     0      0        0 eth0
default 10.66.67.193    0.0.0.0         UG    0      0        0 eth0

6. I have installed uml-utilities & bridge utilities.
7. finally I wrote a IP frame to tun0 device . The IP packet was for opening a ftp session on other machine (10.66.67.220.

I could seee the packet received in tun0 device using ifconfig and wireshark.

Code:
tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:10.66.67.247  P-t-P:10.66.67.247  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:1 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:60 (60.0 b)  TX bytes:0 (0.0 b)

The IP Packet which I sent is received in the tun0 device, but furhter its not been routed to the eth0 device.

My question is, how do I route the IP packets recevied in tun0 device to the network via eth0 and vice versa.

Is there any package or driver i need to install inorder to configure the tun device for routing it to the eth0

Thanks for your inputs in Advance
Johnnie Alan J
 

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Route classifier in tc(8)					       Linux						 Route classifier in tc(8)

NAME
route - route traffic control filter SYNOPSIS
tc filter ... route [ from REALM | fromif TAG ] [ to REALM ] [ classid CLASSID ] [ action ACTION_SPEC ] DESCRIPTION
Match packets based on routing table entries. This filter centers around the possibility to assign a realm to routing table entries. For any packet to be classified by this filter, a routing table lookup is performed and the returned realm is used to decide on whether the packet is a match or not. OPTIONS
action ACTION_SPEC Apply an action from the generic actions framework on matching packets. classid CLASSID Push matching packets into the class identified by CLASSID. from REALM fromif TAG Perform source route lookups. TAG is the name of an interface which must be present on the system at the time of tc invocation. to REALM Match if normal (i.e., destination) routing returns the given REALM. EXAMPLES
Consider the subnet 192.168.2.0/24 being attached to eth0: ip route add 192.168.2.0/24 dev eth0 realm 2 The following route filter will then match packets from that subnet: tc filter add ... route from 2 classid 1:2 and pass packets on to class 1:2. NOTES
Due to implementation details, realm values must be in a range from 0 to 255, inclusive. Alternatively, a verbose name defined in /etc/iproute2/rt_realms may be given instead. SEE ALSO
tc(8), ip-route(8) iproute2 21 Oct 2015 Route classifier in tc(8)
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