Why does NetworkManager report IPv6 related warnings when IPv6 is disabled in the kernel?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux (RHEL) 7 and above
  • NetworkManager
  • IPv6

Issue

  • Why does NetworkManager report IPv6 related warnings when IPv6 is disabled in the kernel?
NetworkManager[5621]: <warn>  [1657217781.6789] platform-linux: do-add-ip6-address[2001:db8::]: failure 95 (Operation not supported)
NetworkManager[5621]: <warn>  [1657217781.6789] platform-linux: do-add-ip6-address[2001:db8::]: failure 95 (Operation not supported)
NetworkManager[5621]: <warn>  [1657217781.6789] platform-linux: do-add-ip6-address[2001:db8::]: failure 95 (Operation not supported)

Resolution

Disable IPv6 on the NetworkManager connection and bounce the interface. The below commands disable IPv6 for the connection and will bounce the interface.

#nmcli con mod <connection name> ipv6.method disabled
#nmcli con down <connection name> 
#nmcli con up <connection name>

Root Cause

NetworkManager is trying to configure the IPv6 address. Because the existing NetworkManager connection has IPv6 enabled. But getting the above warnings since the IPv6 support is completely disabled at the kernel level.

Diagnostic Steps

  • Check if IPv6 is disabled at kernel.
  • Check if the NetworkManager connection has IPv6 enabled.

The below example shows IPv6 enabled as link-local in NetworkManager:

[root@node2.example.com~]# egrep  -o 'ipv6.disa[^ ]*' /proc/cmdline
ipv6.disable=1

[root@node2.example.com ~]# nmcli connection show enp1s0  | grep  ipv6.method
ipv6.method:                             link-local

This solution is part of Red Hat’s fast-track publication program, providing a huge library of solutions that Red Hat engineers have created while supporting our customers. To give you the knowledge you need the instant it becomes available, these articles may be presented in a raw and unedited form.

Comments