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.

Answer 1

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.