[CentOS] ip6tables REJECT target 3s timeout

Markus Falb markus.falb at fasel.at
Wed Nov 21 16:40:05 UTC 2012


Hi,
I am trying to get ipv6 firewall running. I did a very simple ip6tables
rules and noticed very long running yum updates. I think that happened
because firewall is dropping outgoing packets to port 80. Well, I
thought to mitigate the issue and changed outgoing from drop to reject.

Now I try manually

# strace telnet 2a02:180:ffff:1::551f:b966 80
...
connect(3, {sa_family=AF_INET6, sin6_port=htons(80), inet_pton(AF_INET6,
"2a02:180:ffff:1::551f:b966", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, 28

3 second delay

) = -1 ECONNREFUSED (Connection refused)
...

The ECONNREFUSED is quite expected of course, but what is not expected
that the connect syscall lasts 3 seconds. This 3 second delay is not
happening with a equivalent telnet to a IPv4 address.

Why is this 3 second delay?
-- 
Kind Regards, Markus Falb

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