Disable inet6 link-local address from one interface

Question

Anyone know how I can disable the link-local address from just one interface on CentOS 5.6? This is what I tried:

root-> egrep -i ipv6 /etc/sysconfig/network-scripts/ifcfg-eth0
IPV6INIT=no
IPV6_AUTOCONF=no
IPV6_ROUTER=no

root-> egrep -i ipv6 /etc/sysctl.conf 
#disable ipv6 from eth0
net.ipv6.conf.eth0.disable_ipv6 = 1
net.ipv6.conf.eth0.autoconf = 0

root-> ip -f inet6 a show dev eth0
 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::20c:29ff:fe3c:16af/64 scope link 
       valid_lft forever preferred_lft forever


root-> ip -f inet6 a del fe80::20c:29ff:fe3c:16af/64 dev eth0

root-> ip -f inet6 a show dev eth0

Nothing here

But then the address comes back:

root-> ifdown eth0 && ifup eth0

root-> ip -f inet6 a show dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::20c:29ff:fe3c:16af/64 scope link 
       valid_lft forever preferred_lft forever

Thanks.

score 1 · Answer 1 · answered Mar 10 '12 at 15:15

It will be the CentOS network scripts doing something that go against what you're trying to do. My guess is that if you do everything as you have up until:

ifdown eth0 && ifup eth0

but instead run:

ifconfig eth0 down && ifconfig eth0 up

you should be OK. ifdown and ifup are system scripts which do much more than just bringing an interface up and down. I suggest writing your own custom script to modify the properties of the interface, outwith ifdown/ifup.

Or raise this as a bug with CentOS as quite possibly their system scripts aren't strictly doing what they are supposed to be doing, in this case.

Disable inet6 link-local address from one interface

1 Answers1