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I'm trying to setup a GRE tunnel between an Ubuntu system and a UML (running on a different system). This is how the systems were configured:

  1. UML

Boot arguments:

./vmlinux ubd0=guest3,uml-ext2-img con0=null con=fd:0,fd:1 umid=guest3 mem=32m eth0=tapng,,tap1 eth1=gre,,10.0.0.1,10.0.0.2,9 cgroup_disable=memory init=/etc/preinit


root@...:/# ifconfig
eth0      Link encap:Ethernet  HWaddr 5A:86:C4:0D:19:F5
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:43 errors:0 dropped:22 overruns:0 frame:0
      TX packets:777 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:2321 (2.2 KiB)  TX bytes:312354 (305.0 KiB)
      Interrupt:5

eth1      Link encap:Ethernet  HWaddr 76:5A:7B:B7:D9:F6
      inet addr:192.168.252.1  Bcast:192.168.252.255  Mask:255.255.255.0
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:611 errors:0 dropped:611 overruns:0 frame:0
      TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:42518 (41.5 KiB)  TX bytes:402 (402.0 B)
      Interrupt:5

lo        Link encap:Local Loopback
      inet addr:127.0.0.1  Mask:255.0.0.0
      UP LOOPBACK RUNNING  MTU:16436  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0
      RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
  1. Ubuntu

This is the entry I added to /etc/network/interfaces:

auto gre1
iface gre1 inet static
    address 192.168.252.110
    netmask 255.255.255.252
    pre-up iptunnel add gre1 mode gre local 10.0.0.1 remote 10.0.0.2 ttl 255
    up ifconfig gre1 multicast
    pointtopoint 192.168.252.1
    post-down iptunnel del gre1


ubuntu# ifconfig

eth0      Link encap:Ethernet  HWaddr 78:e7:d1:c6:23:71
      inet addr:10.0.0.1  Bcast:10.78.49.255  Mask:255.255.255.0
      inet6 addr: fe80::7ae7:d1ff:fec6:2371/64 Scope:Link
      inet6 addr: 2001:220:abcd::20/64 Scope:Global
      inet6 addr: 2001:220:abcd:70::26/64 Scope:Global
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:3331 errors:0 dropped:284 overruns:0 frame:0
      TX packets:543 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:1200307 (1.2 MB)  TX bytes:114051 (114.0 KB)
      Interrupt:17

gre1      Link encap:UNSPEC  HWaddr 0A-4E-31-4B-00-00-00-00-00-00-00-00-00-00-00-00
      inet addr:192.168.252.110  P-t-P:192.168.252.110  Mask:255.255.255.252
      inet6 addr: fe80::5efe:a4e:314b/64 Scope:Link
      UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1476  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0
      RX bytes:0 (0.0 B)  TX bytes:168 (168.0 B)

The ubuntu box is able to ping the IP 192.168.252.1, but strangely I don't see packets going out to 10.0.0.2. Also, the UML is not able to ping 192.168.252.110.

Is this configuration correct or is there something missing?

Thanks!

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