I have openstack deployment with a controller, one compute node and a network node. I want to mirror all the traffic from a tenant network to a separate host where I have some packet monitoring tools (like IDS).

I launched two VMs for a test. I added a mirror port in the compute node and I made the mirror port a type of GRE tunnel to the remote host. From the remote host I created the other end of the tunnel.

Here is the output of ovs-vsctl show command from compute node

Bridge br-tun
    fail_mode: secure
    Port patch-int
        Interface patch-int
            type: patch
            options: {peer=patch-tun}
    Port "vxlan-ac106207"
        Interface "vxlan-ac106207"
            type: vxlan
            options: {df_default="true", in_key=flow, local_ip="z.z.z.z", out_key=flow, remote_ip="y.y.y.y"}
    Port br-tun
        Interface br-tun
            type: internal
Bridge br-int
    fail_mode: secure
    Port br-int
        Interface br-int
            type: internal
    Port patch-tun
        Interface patch-tun
            type: patch
            options: {peer=patch-int}
    Port "qvod3ef531d-27"
        tag: 1
        Interface "qvod3ef531d-27"
    Port "qvo7d435b5f-d2"
        tag: 1
        Interface "qvo7d435b5f-d2"
    Port snooper
        Interface snooper
            type: gre
            options: {remote_ip="x.x.x.x"}
ovs_version: "2.4.1"

where x.x.x.x is the IP of remote host

the out put of ovs-vsctl show from the remote host is

Bridge br-tun
    Port "vnet0"
        Interface "vnet0"
    Port gremirror
        Interface gremirror
            type: gre
            options: {remote_ip="p.p.p.p"}
    Port br-tun
        Interface br-tun
            type: internal
ovs_version: "2.0.2"

where p.p.p.p is the IP of the compute node

For the VM-VM communication (ping from one VM to other) it works fine. I can see all the packets in the remote host. But when there is a packet from outside I can only see the return packets (i.e. if I ping one of the VM from outside of the cloud, I will see only the return packets from the VM in the remote host) ? why is the incoming packet not mirrored (forwarded through tunnel ) ? what am I missing ?

Thank you for the help in advance.