Re: connect() with AF_INET6 freezes on some Debian/unstable machine

[Vincent Lefevre <vincent@vinc17.net>]

On 2015-04-10 15:55:38 +0300, Reco wrote:
> Out of curiosity, does the problem reproduce if avahi-daemon is
> stopped?

Yes. I've purged the avahi-daemon daemon package (I don't think
I need it), net.ipv6.conf.all.accept_ra is still set to 0 in
/etc/sysctl.conf, and after rebooting the machine:

ypig:~> ip -6 a l dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2001:1::21f:29ff:fe04:3efb/64 scope global mngtmpaddr dynamic 
       valid_lft 2591997sec preferred_lft 604797sec
    inet6 fe80::21f:29ff:fe04:3efb/64 scope link 
       valid_lft forever preferred_lft forever

ypig:~> time telnet www.vinc17.net 80
Trying 2001:4b98:dc0:45:216:3eff:fe9b:eb2f...
^C
zsh: interrupt  telnet www.vinc17.net 80
telnet www.vinc17.net 80  0.00s user 0.00s system 0% cpu 22.279 total

Then...

> And, there's always ip6tables, i.e.
> 
> ip6tables -I INPUT -p icmpv6 --icmpv6-type 134 -j DROP

I've modified my /etc/network/interfaces file to have now:

allow-hotplug eth0
iface eth0 inet dhcp
  pre-up ip6tables -I INPUT -p icmpv6 --icmpv6-type 134 -j DROP

then I rebooted, and the problem seems to be solved!

ypig:~> ip -6 a l dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::21f:29ff:fe04:3efb/64 scope link 
       valid_lft forever preferred_lft forever

ypig:~> time telnet www.vinc17.net 80
Trying 92.243.22.117...
[...]

Thanks!

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)