Bug #338

connmark and ipv6 iptables are a bad combination

Added by Dave Täht on Feb 11, 2012. Updated on Apr 21, 2012.
New Urgent Dave Täht


I have been battling various ipv6 related bugs for a while. For example, I tried
to make openwrt’s shaper do ipv6 and stuff like this will hang the interface
on x86 AND cerowrt.

  1. This is my bad boy
    ip6tables -t mangle -A qos_Default -p tcp -m length –length :128 -m mark ! –mark 4/0xff -m tcp –tcp-flags ALL SYN -j MARK –set-mark 1/0xff
    ip6tables -t mangle -A qos_Default -p tcp -m length –length :128 -m mark ! –mark 4/0xff -m tcp –tcp-flags ALL ACK -j MARK –set-mark 1/0xff


  • simple_bug (application/octet-stream; 3.0 kiB) Dave Täht Feb 11, 2012


Updated by Dave Täht on Feb 11, 2012.
It may not be limited to the negate mark option, either.

I suspect there are more ipv6 related bugs than this lurking in ip6tables

Updated by Dave Täht on Feb 12, 2012.
and, after duplicating this on 3 machines, rebooted them all…

and with the simplified script, they no longer go boom. Have to recreate the complex scenario now.

Updated by Dave Täht on Feb 15, 2012.
and then, I managed to get it to happen again. But it’s subtle.

I don’t know what to point at anymore. ifb? ip6tables? conntrack?

Updated by Dave Täht on Apr 21, 2012.

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