[CentOS] ip6tables REJECT target 3s timeout

Markus Falb markus.falb at fasel.at
Thu Nov 22 11:21:13 UTC 2012


On 21.11.2012 17:40, Markus Falb wrote:
> 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?

There are 2 destination unreachables sent, one immediate and the second
after 3 seconds. There are also 2 log entries from ip6tables. It looks
like the connect() is really trying a second time.
-- 
Kind Regards, Markus Falb

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