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

[Reco <recoverym4n@gmail.com>]

 Hi.

On Fri, Apr 10, 2015 at 03:31:11PM +0200, Vincent Lefevre wrote:
> 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...

Then we have a kernel bug here, no doubt.

I don't recall any userspace which listens RA in Debian, so clearly
Jessie's kernel must ignore accept_ra. I'll check it in a couple of
hours, just need to get myself to the place with the right setup.


> > 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!

You're welcome.

Reco