Article ID: 112044, created on Aug 24, 2011, last review on May 11, 2014

  • Applies to:
  • Virtuozzo hypervisor 5.0


CentOS 5.6 virtual machine does not have IPv6 networking, even though IPv6 modules are loaded.
Errors like those below can be observed during a restart of the networking service:
-bash-3.2# /etc/init.d/network restart 
Shutting down interface eth0: [ OK ] 
Shutting down loopback interface: [ OK ] 
FATAL: Module off not found. 
CRITICAL : [ipv6_test] Kernel is not compiled with IPv6 support 
Bringing up loopback interface: [ OK ] 
Bringing up interface eth0: FATAL: Module off not found. 
CRITICAL : [ipv6_test] Kernel is not compiled with IPv6 support 
                                                           [ OK ] 
FATAL: Module off not found. 
CRITICAL : [ipv6_test] Kernel is not compiled with IPv6 support 


Most likely, IPv6 is disabled in /etc/modprobe.conf:
~# cat /etc/modprobe.conf
alias scsi_hostadapter ata_piix
options ip_conntrack ip_conntrack_disable_ve0=1
options ipv6 disable=1

This issue is a known limitation of RHEL 5.6 and CentOS 5.6:
Red Hat bug # 677653 IPv6 support is disabled when IPv6 is not used during installation

It is fixed in RHEL 5.7 and CentOS 5.7.

To work around the problem, delete the options ipv6 disable=1 line from /etc/modprobe.conf and restart the VM.

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