netdev - Re: GRE devices and MULTICAST flag.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20110923211625.GA2409116@jupiter.n2.diac24.net>
Date:	Fri, 23 Sep 2011 23:16:25 +0200
From:	David Lamparter <equinox@...c24.net>
To:	Ben Greear <greearb@...delatech.com>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: GRE devices and MULTICAST flag.

On Fri, Sep 23, 2011 at 01:42:53PM -0700, Ben Greear wrote:
> On 09/23/2011 12:56 PM, Ben Greear wrote:
> > I was under the impression that GRE tunnels could support MULTICAST
> > traffic, but the MULTICAST flag is not set. This is making the xorp
> > router crap out because it checks the MULTICAST flag and will
> > not start multicast on the interface if it's not set....
> >
> > Is it supposed to be set?
> >
> > 7: gre0: <NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
> > link/gre 0.0.0.0 brd 0.0.0.0
> > 8: netb: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
> > link/gre 192.168.100.223 peer 192.168.100.138
> > inet 10.0.1.1/32 scope global netb
> 
> Well, ifconfig netb multicast seems to add the flag,
> so maybe all is as it should be.

I distinctively remember that the MULTICAST flag is supposed to be an
input to the kernel, not a feature-indication flag output. I'm quite
unsure where I picked this up, but I remember using it in that way that
xorp does and then finding out it's wrong.

-David

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html