[SOLVED] [Ubuntu] How to setup VLAN on same subnet as Ethernet

junkyhlm · 01-09-2013, 04:28 AM

So this is what i'm trying to do:

I have a physical NIC with dev name eth0 with ip 192.168.1.2 and gateway 192.168.1.1 and I want to setup a VLAN with ip 192.168.1.x and same gateway as eth0.

Setting up the VLAN runs smoothly and i give the VLAN a iface name of eth0.10 and an ip of 192.168.1.69. Now when trying to establish a connection i get an error:

Code:

filserver:~$ sudo ifup eth0.10
Set name-type for VLAN subsystem. Should be visible in /proc/net/vlan/config
RTNETLINK answers: File exists
Failed to bring up eth0.10.

So how do I get the VLAN to connect to the internet and what does the error message mean? My guess s that it have something to do with the broadcast.

Please help!

Settings: /etc/network/interfaces

Code:

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp
        address 192.168.1.2
        netmask 255.255.255.0
        network 192.168.1.0
        gateway 192.168.1.1

iface eth0.10 inet static
        address 192.168.1.69
        netmask 255.255.255.0
        gateway 192.168.1.1

I have removed the auto eth0.10 since i dont want to establish it at startup

Settings: ifconfig

Code:

filserver:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:1a:4d:5b:02:5c
          inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::21a:4dff:fe5b:25c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11670807 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22363842 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:833725090 (833.7 MB)  TX bytes:31876321312 (31.8 GB)
          Interrupt:44 Base address:0x4000

eth0.10   Link encap:Ethernet  HWaddr 00:1a:4d:5b:02:5c
          inet addr:192.168.1.69  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::21a:4dff:fe5b:25c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:432 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:41501 (41.5 KB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:4899 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4899 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:697405 (697.4 KB)  TX bytes:697405 (697.4 KB)

Settings: netstat output

Code:

filserver:~$ netstat -anr
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         192.168.1.1     0.0.0.0         UG        0 0          0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0.10

Test: ping output domain name

Code:

filserver:~$ ping -I eth0.10 www.dn.se
PING a1910.g1.akamai.net (23.60.69.161) from 192.168.1.2 eth0.10: 56(84) bytes of data.
From filserver.local (192.168.1.69) icmp_seq=1 Destination Host Unreachable
From filserver.local (192.168.1.69) icmp_seq=2 Destination Host Unreachable
From filserver.local (192.168.1.69) icmp_seq=3 Destination Host Unreachable
^C
--- a1910.g1.akamai.net ping statistics ---
5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 4025ms
pipe 3

Test: ping output ip addr

Code:

filserver:~$ ping -I eth0.10 8.8.8.8
PING 8.8.8.8 (8.8.8.8) from 192.168.1.2 eth0.10: 56(84) bytes of data.
From 192.168.1.69 icmp_seq=1 Destination Host Unreachable
From 192.168.1.69 icmp_seq=2 Destination Host Unreachable
From 192.168.1.69 icmp_seq=3 Destination Host Unreachable
^C
--- 8.8.8.8 ping statistics ---
5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 4023ms
pipe 3

Ser Olmy · 01-10-2013, 12:32 AM

Quote:

Originally Posted by junkyhlm

I have a physical NIC with dev name eth0 with ip 192.168.1.2 and gateway 192.168.1.1 and I want to setup a VLAN with ip 192.168.1.x and same gateway as eth0.

You do realize that a VLAN is a separate layer 2 network, and that having the same IP subnet assigned to two different physical networks makes little sense?

When you create a VLAN interface, it is bound to a physical interface. Outgoing traffic from the VLAN interface will be encapsulated using 802.1q VLAN tags, so you'll need a 802.1q-capable host, switch or router at the other end for this to work.

Also, having two NICs (one physical, one VLAN) in the same machine does not mean having two gateways. IP addresses are assigned per NIC, gateways are assigned per host. In any case, two NICs belonging to different VLANs cannot share the same gateway, as the NICs belong to different layer 2 networks.

I may be wrong, but I think perhaps VLAN is not what you're looking for. Exactly what are you trying to accomplish?

junkyhlm · 01-10-2013, 12:56 AM

First of all, thank you for your reply.
I am testing a anonymizer service that is using OpenVPN. I'm running a server with rtorrent and apache2 for example and I only want to tunnel the traffic to and from rtorrent through the VPN. I have been testing this alot and concluded that it is a policy routing issue.

First I've setup a VLAN on the 10.x.x.x IP range and everything worked fine, all but one simple little thing: I had no connection to the internet. DOH! i had forgotten the gateway and since i've only have one router/switch (DLink DIR-655) with the assigned ip 192.168.1.1 and from what I've learned the 10.x.x.x range cannot communicate with 192.168.1.0/24 so setting 192.168.1.1 as gateway for the VLAN did'nt work.

Any tips?

junkyhlm · 01-11-2013, 03:12 AM

I've resolved this whit another nic.