Friborz, any progress?
not a gre expert but glad to see you get on with your problem.

On Sat, Jan 6, 2024 at 10:39 PM Fariborz Navidan <[email protected]> wrote:
>
> Hi Dear Experts,
>
> We are running Cs 4.15.0.0 with 2 KVM hosts having security groups enabled
> zone. We have a VM which a GRE tunnel has been setup between it and a
> server outside our network. Both hosts had been rebooted a few days ago due
> to power interruption. Before the reboot happens, the GRE tunnel was
> working properly on the mentioned VM. However after the reboot, GRE tunnel
> can be established but machines cannot reach each other via the tunnel's
> private IP address. All ports and protocols are already added to ingress
> rule set of security group which VM belongs to.
>
> Below is output of "ip a" and "ip r" commands on the VM running on our CS
> infrastructure.
>
> root@cdn-fr-1-kajgana-net:~# ip a
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group
> default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>     inet 127.0.0.1/8 scope host lo
>        valid_lft forever preferred_lft forever
>     inet6 ::1/128 scope host
>        valid_lft forever preferred_lft forever
> 2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state
> UP group default qlen 1000
>     link/ether 1e:00:85:00:02:4d brd ff:ff:ff:ff:ff:ff
>     inet 164.132.223.34/28 brd 164.132.223.47 scope global ens3
>        valid_lft forever preferred_lft forever
>     inet6 fe80::1c00:85ff:fe00:24d/64 scope link
>        valid_lft forever preferred_lft forever
> 3: gre0@NONE: <NOARP> mtu 1476 qdisc noop state DOWN group default qlen 1000
>     link/gre 0.0.0.0 brd 0.0.0.0
> 4: gretap0@NONE: <BROADCAST,MULTICAST> mtu 1462 qdisc noop state DOWN group
> default qlen 1000
>     link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
> 5: erspan0@NONE: <BROADCAST,MULTICAST> mtu 1450 qdisc noop state DOWN group
> default qlen 1000
>     link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
> 6: gre1@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state
> UNKNOWN group default qlen 1000
>     link/gre 164.132.223.34 peer 89.205.123.34
>     inet 192.168.169.1/30 scope global gre1
>        valid_lft forever preferred_lft forever
>     inet6 fe80::200:5efe:a484:df22/64 scope link
>        valid_lft forever preferred_lft forever
>
> root@cdn-fr-1-kajgana-net:~# ip r
> default via 164.132.223.46 dev ens3
> 164.132.223.32/28 dev ens3 proto kernel scope link src 164.132.223.34
> 192.168.169.0/30 dev gre1 proto kernel scope link src 192.168.169.1
>
> IP address of tunnel's other endpoint is 192.168.169.2 which is unreachable
> from the VM. It looks like GRE tunnel has been established but traffic
> cannot be p[assed through.
>
> Is there something we need to do with iptables rules on the hosts to allow
> GRE traffic or is there anything else we can do to address this issue?
>
> Thanks in advance.
> Regards.



-- 
Daan

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