Linux - how to make two bridges on one NIC?

Networking
1

Hello,

I have a problem with making two bridges on my proxmox installation.

I can’t bridge vmbr0 to vmbr1 since vmbr0 is a bridge.
And I can’t bridge physical interface to vmbr1 since it’s already bridged to vmbr0.

I need that thing to work this way because I have to have at least two different MACs on the same NIC.
(It’s because OVH is using static routing (IP is bound to MAC) )

I’ve already seached for that on the internet but I can’t find any useful tutorial nor anything that I’m able to understand and apply in my case.

2

If the MACs are different… why not just connect both to the same bridge?

3

What do you mean?

Something like this?

auto lo
iface lo inet loopback

iface enp0s3 inet manual

allow-hotplug enp0s3

auto vmbr0
iface vmbr0 inet static
        address  192.168.0.31
        netmask  255.255.255.0
        gateway  192.168.0.1
        bridge_ports enp0s3
        bridge_stp off
        bridge_fd 0
        bridge_vlan_aware yes

auto vmbr0:1
iface vmbr0:1 inet static
        address  192.168.0.55
        netmask  255.255.255.0
        hwaddress ether 00:11:22:33:44:55
4

Um… I still don’t have a solution to my problem : /
One possible one was to make a virtual interface and assign custom mac to that one, but I don’t know how to do that.

5

something like this?

auto lo
iface lo inet loopback

iface enp0s3 inet manual

iface enp0s3:1 inet manual

allow-hotplug enp0s3

auto vmbr0
iface vmbr0 inet static
        address  192.168.0.31
        netmask  255.255.255.0
        gateway  192.168.0.1
        bridge_ports enp0s3
        bridge_stp off
        bridge_fd 0
        bridge_vlan_aware yes

auto vmbr1
iface vmbr1 inet static
        bridge_ports enp0s3:1
       address ......

EDIT:

wait, you need to assign the ip addresses to the bridge or the vms?

6

The problem that I have is that I have to have second interface with custom MAC that will be visible to switch outside of my server.

7

Ideally, the solution to this would be to attach one bridge to a vlan and one to the physical adapter. I don’t know if it’s still the case, but for a while, you couldn’t connect multiple nics to a single subnet in Linux or you’d run into problems.

I’m not sure if that’s what you’re looking for though.

8

I just want to have two virtual adapters on the host with different MACs and IPs.

One of them acticng as a NAT for few containers and another one acting as a bridge for other containers that have their own MACs and IPs.

9

I think the example that @jazz gave above should work for you in this case.

I may be misunderstanding the parameters though. Let me do a little diagram to be sure we’re on the same page.

Something like this?

 + ethX
 |
 + - +  Bridge 1 (NAT) (192.168.0.102)
 |   |
 |   + VM (192.168.0.102:8080)
 |   + VM (192.168.0.102:6789)
 |   + VM (192.168.0.102:1234)
 |
 + - +  Bridge 2 (bridge) (192.168.0.103)
     |
     + VM (192.168.0.104)
     + VM (192.168.0.105)
     + VM (192.168.0.106)
1 Like
10

I like the idea of the sub interface that was said above… Why do you need two different bridges tho?

1 Like
11

With KVM you can assign the same bridge interface to multiple VMs and they will each have a unique mac address, the bridge itself does not need an IP. You don’t need to make multiple bridge interfaces.

1 Like
12

macvtap in kvm behaves very nicely if you want to assign as many virtual MAC address as you like and make them visible to the outside world.

13

Look at macvlan/ ipvlan. It’ll help you create a virtual network interface with a separate mac on top of same physical interface.

1 Like
14

Interesting tread. Im more I want a vm with a VPN locked down so it cant leakl my ip.

15

Yes, but Bridge 1 and 2 have to have different MACs.

16

But I want to avoid using KVM, I know that this would be arelly easy if I’d use KVM, but I don’t want to.

Containers just suit better my usecase.

17

Sorry, I thought you said you were using KVM

18

just try sub interfaces.

1 Like
19

Little update on this problem:

Turns out that ovh is not limiting me to virtual MACs with additional IPs so I was able to just make subinterface of vmbr0 with different IP and make a bridge out of that.

Thanks everyone for help.