Automatic IPv6 due to broadcast

Mon Apr 16 18:09:46 UTC 2012

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
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