To completely disable ipv6 in Redhat: 1) Modify /etc/modprobe.conf (add) alias ipv6 off alias net-pf-10 off options ipv6 disable=1 2) Modify /etc/sysconfig/network (add) NETWORKING_IPV6=no I usually also add NOZEROCONF=yes That should completely disable ipv6 in Redhat 5.x ---- Matthew Huff | 1 Manhattanville Rd Director of Operations | Purchase, NY 10577 OTA Management LLC | Phone: 914-460-4039 aim: matthewbhuff | Fax: 914-460-4139
-----Original Message----- From: Anurag Bhatia [mailto:me@anuragbhatia.com] Sent: Monday, April 16, 2012 2:10 PM To: NANOG Mailing List Subject: Automatic IPv6 due to broadcast
Hello everyone
Just got a awfully crazy issue. I heard from our support team about failure of whois during domain registration. Initially I thought of port 43 TCP block or something but found it was all ok. Later when ran whois manually on server via terminal it failed. Found problem that server was connecting to whois server - whois.verisign-grs.com. I was stunned! Server got IPv6 and not just that one - almost all. This was scary - partial IPv6 setup and it was breaking things.
In routing tables, routes were all going to a router which I recently setup for testing. That router and other servers are under same switch but by no means I ever configured that router as default gateway for IPv6. I found option of "broadcast" was enabled on router for local fe80... address and I guess router broadcasted IPv6 and somehow (??) all servers found that they have a IPv6 router on LAN and started using it - automated DHCP IPv6?
I wonder if anyone else also had similar issues? Also, if my guesses are correct then how can we disable Red Hat distro oriented servers from taking such automated configuration - simple DHCP in IPv6 disable?
Thanks
--
Anurag Bhatia anuragbhatia.com or simply - http://[2001:470:26:78f::5] if you are on IPv6 connected network!
Twitter: @anurag_bhatia <https://twitter.com/#!/anurag_bhatia> Linkedin: http://linkedin.anuragbhatia.com