[SOLVED] fresh installed guest LXC: Network is unreachable

[proxbob]

Hello,

I have a fresh installed proxmox 5 dedicated server.

 pveversion
pve-manager/5.2-12/ba196e4b (running kernel: 4.15.18-9-pve)

when I create a CT with the default CentOS6 or 7 image, the guest can't connect to the internet.

from guest :

[root@CentOS6 /]# ping 8.8.8.8
connect: Network is unreachable
[root@CentOS6 /]# ifconfig
eth0      Link encap:Ethernet  HWaddr 02:00:00:xx:xx:xx
          inet6 addr: fe80::xx:xxxx:xxxx/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:19 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1126 (1.0 KiB)  TX bytes:714 (714.0 b)

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:65536  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:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

from host:

root@proxmox_host:~$ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback


# vmbr0: Bridging. Make sure to use only MAC adresses that were assigned to you.
auto vmbr0
iface vmbr0 inet static
        address IP.IP.IP.IP/24
        gateway IP.IP.IP.254
        bridge_ports eno1
        bridge_stp off
        bridge_fd 0

What's strange is if I go on proxmox interface to Guest Network, and change the network device name from eth0 to anything else (like xxx123) while the guest is running, the guest become with full connectivity:

[root@CentOS6 /]# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=121 time=4.12 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=121 time=4.23 ms
^C
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1911ms
rtt min/avg/max/mdev = 4.125/4.180/4.235/0.055 ms
[root@CentOS6 /]# ifconfig
eth01     Link encap:Ethernet  HWaddr 02:00:00:xx:xx:xx
          inet addr:IP.IP.IP.IP  Bcast:0.0.0.0  Mask:255.255.255.255
          inet6 addr: fe80::xx:xxxx:xxxx/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:413 errors:0 dropped:1 overruns:0 frame:0
          TX packets:96 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:24269 (23.7 KiB)  TX bytes:4904 (4.7 KiB)

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:65536  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:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

But if I reboot the guest, the problem occure again.



What can cause this ?

Regards,

 

[proxbob]

* resolved

that ip was configured on another running CT, even if it was pointing to the centOS6 mac, he could not use it.

I found it adding :

IPV4_FAILURE_FATAL=yes

to :
/etc/sysconfig/network-scripts/ifcfg-eth0

and restarting network :

service network restart

it gave

[root@centos /]# service network restart
Shutting down interface eth0:                              [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0:  Determining if ip address IP.IP.IP.IP is already in use for device eth0...
Error, some other host (02:00:00:xx.xx.xx) already uses address  IP.IP.IP.IP
                                                           [FAILED]

not I just deleted that IP from the other CT and rebooted it.

 

[Miraculix_de]

Similar issue:
could not curl https://plex.tv but google.de worked.

Reason: IP was configured but gateway left empty.