Thread: Help with forwarding packets from a Tun to an Eth interface

[********solved*********]

morning all,

have c-program creates tun (tun0) , writes it. part works fine, want packets forwarded on eth0 (different network), unfortunately not working.

if force ping src of tun0 exits via eth0 - happy routes correct.

additional information can provide me resolve appreciated - see below interfaces information.

tun setup these flags:

code:

iff_up | iff_running | iff_noarp | iff_promisc

after program sets them set ip addresses. network resembles this:

code:

machine1:        tun0      |   |     eth0    |   192.168.1.1/28 | - | 10.1.1.1/16 |---|                                        |  machine2:                             |        tun0      |   |     eth0    |   |   192.168.2.1/28 | - | 10.1.2.1/16 |---|

ip forwarding on via:

code:

sysctl -w net.ipv4.ip_forward=1

ifconfig gives me this:

code:

tun0      link encap:unspec  hwaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00              inet addr:192.168.1.1  p-t-p:192.168.1.1  mask:255.255.255.240            pointopoint running noarp promisc multicast  mtu:1500  metric:1            rx packets:694 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:80504 (80.5 kb)  tx bytes:0 (0.0 b)    eth0      link encap:ethernet  hwaddr 52:54:00:9a:bc:9a              inet addr:10.1.1.1  bcast:10.1.255.255  mask:255.255.0.0            inet6 addr: fe80::5054:ff:fe9a:bc9a/64 scope:link            broadcast running multicast  mtu:1500  metric:1            rx packets:18076 errors:0 dropped:65 overruns:0 frame:0            tx packets:537 errors:0 dropped:0 overruns:0 carrier:0            collisions:0 txqueuelen:1000             rx bytes:2017435 (2.0 mb)  tx bytes:74778 (74.7 kb)    lo        link encap:local loopback              inet addr:127.0.0.1  mask:255.0.0.0            inet6 addr: ::1/128 scope:host            loopback running  mtu:16436  metric:1            rx packets:46 errors:0 dropped:0 overruns:0 frame:0            tx packets:46 errors:0 dropped:0 overruns:0 carrier:0            collisions:0 txqueuelen:0             rx bytes:3450 (3.4 kb)  tx bytes:3450 (3.4 kb)

(it worth noting setting ip addresses manually, after program has set tun. using ifconfig tun0 192.168.1.1/28.

, routing table:

code:

default via 10.1.2.1 dev eth0  metric 100   10.1.0.0/16 dev eth0  proto kernel  scope link  src 10.1.1.1   192.168.0.0/16 dev eth0  scope link  src 192.168.14.1   192.168.1.0/28 dev tun0  proto kernel  scope link  src 192.168.1.1

i've been pulling hair out bit this, , have tried several solutions have found while researching on internet. including iptables forwarding having no luck this.

if tcpdump tun0 see:

code:

11:43:00.847394 ip 192.168.1.1 > 192.168.2.1

but nothing of sorts while tcpdump on eth0

appreciated.

many thanks,

chris.

follow up:

have come solution. appears tun route user space , other tun/taps.

have re-coded program read in on tun, read out complete sendto() raw socket (ipproto_raw iphdr_incl), drops packet stack , lets sort out!

has allowed me achieve want, , packets being routed out of machine correctly.

regards,

chris.

edit: not sure how set 'solved', mod honours - thank you.

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